PROCESSES FOR THE PREPARATION OF ARGINASE INHIBITORS AND THEIR SYNTHETIC INTERMEDIATES

Abstract

Provided herein are processes and intermediates useful for the preparation of certain compounds, including a compound of formula 21 or formula 22

##STR00001##

or a pharmaceutically acceptable salt of either.

Claims

1. A process for preparing a compound of formula 21 ##STR00260## or a pharmaceutically acceptable salt thereof, wherein: R.sup.2 is H, (C.sub.1-C.sub.6)alkyl, —CH.sub.2OZ, —CH(CH.sub.3)OZ, —CH.sub.2SZ, —(CH.sub.2).sub.2SCH.sub.3, —CH.sub.2CONZ.sub.2, —(CH.sub.2).sub.2CONZ.sub.2, —CH.sub.2CO.sub.2Z, —(CH.sub.2).sub.2CO.sub.2Z, —(CH.sub.2).sub.4NZ.sub.2, ##STR00261##  and each Z is independently H, (C.sub.1-C.sub.6)alkyl, or a suitable protecting group, comprising treating a compound of formula 20 ##STR00262## or a salt thereof, wherein: R.sup.3 is a substituted or unsubstituted ring selected from aryl and heteroaryl; and PG.sup.1 and PG.sup.2 are independently suitable amine protecting groups, under suitable conditions to deprotect the compound of formula 20 to form the compound of formula 21 or a pharmaceutically acceptable salt thereof.

2. (canceled)

3. A process for preparing a compound of formula 22 ##STR00263## or a pharmaceutically acceptable salt thereof, wherein: R.sup.1 is H or (C.sub.1-C.sub.6)alkyl; R.sup.2 is H, (C.sub.1-C.sub.6)alkyl, —CH.sub.2OZ, —CH(CH.sub.3)OZ, —CH.sub.2SZ, —(CH.sub.2).sub.2SCH.sub.3, —CH.sub.2CONZ.sub.2, —(CH.sub.2).sub.2CONZ.sub.2, —CH.sub.2CO.sub.2Z, —(CH.sub.2).sub.2CO.sub.2Z, —(CH.sub.2).sub.4NZ.sub.2, ##STR00264##  and each Z is independently H, (C.sub.1-C.sub.6)alkyl, or a suitable protecting group, comprising treating a compound of formula 20 ##STR00265## or a salt thereof, wherein: R.sup.3 is a substituted or unsubstituted ring selected from aryl and heteroaryl; and PG.sup.1 and PG.sup.2 are independently suitable amine protecting groups, under suitable conditions to deprotect and condense the compound of formula 20 to form the compound of formula 22 or a pharmaceutically acceptable salt thereof.

4. (canceled)

5. A process for preparing a compound of formula 20 as defined in claim 1, the process comprising hydrolyzing the boronate of a compound of formula 19 ##STR00266## or a salt thereof, wherein: each R is independently (C.sub.1-C.sub.6)alkyl, or: two R groups are optionally taken together with their intervening atoms to form a substituted or unsubstituted monocyclic or bicyclic ring selected from a saturated or partially unsaturated heterocycle; R.sup.2 is H, (C.sub.1-C.sub.6)alkyl, —CH.sub.2OZ, —CH(CH.sub.3)OZ, —CH.sub.2SZ, —(CH.sub.2).sub.2SCH.sub.3, —CH.sub.2CONZ.sub.2, —(CH.sub.2).sub.2CONZ.sub.2, —CH.sub.2CO.sub.2Z, —(CH.sub.2).sub.2CO.sub.2Z, —(CH.sub.2).sub.4NZ.sub.2, ##STR00267## each Z is independently H, (C.sub.1-C.sub.6)alkyl, or a suitable protecting group; R.sup.3 is a substituted or unsubstituted ring selected from aryl and heteroaryl; and PG.sup.1 and PG.sup.2 are independently suitable amine protecting groups, under suitable conditions to hydrolyze the boronate of the compound of formula 19 to form the compound of formula 20 or a salt thereof.

6. (canceled)

7. A process for preparing a compound of formula 19 as defined in claim 5, the process comprising hydroborating a compound of formula 18 ##STR00268## or a salt thereof, wherein: R.sup.2 is H, (C.sub.1-C.sub.6)alkyl, —CH.sub.2OZ, —CH(CH.sub.3)OZ, —CH.sub.2SZ, —(CH.sub.2).sub.2SCH.sub.3, —CH.sub.2CONZ.sub.2, —(CH.sub.2).sub.2CONZ.sub.2, —CH.sub.2CO.sub.2Z, —(CH.sub.2).sub.2CO.sub.2Z, —(CH.sub.2).sub.4NZ.sub.2, ##STR00269## each Z is independently H, (C.sub.1-C.sub.6)alkyl, or a suitable protecting group; R.sup.3 is a substituted or unsubstituted ring selected from aryl and heteroaryl; and PG.sup.1 and PG.sup.2 are independently suitable amine protecting groups, under suitable conditions to hydroborate the compound of formula 18 to form the compound of formula 19 or a salt thereof.

8. (canceled)

9. A process for preparing a compound of formula 18 as defined in claim 7, the process comprising coupling a compound of formula 17 ##STR00270## or a salt thereof, wherein: R.sup.3 is a substituted or unsubstituted ring selected from aryl and heteroaryl; and PG.sup.1 is a suitable amine protecting group, with a compound of formula 16 ##STR00271## or salt thereof, wherein: R.sup.2 is H, (C.sub.1-C.sub.6)alkyl, —CH.sub.2OZ, —CH(CH.sub.3)OZ, —CH.sub.2SZ, —(CH.sub.2).sub.2SCH.sub.3, —CH.sub.2CONZ.sub.2, —(CH.sub.2).sub.2CONZ.sub.2, —CH.sub.2CO.sub.2Z, —(CH.sub.2).sub.2CO.sub.2Z, —(CH.sub.2).sub.4NZ.sub.2, ##STR00272## each Z is independently H, (C.sub.1-C.sub.6)alkyl, or a suitable protecting group; and PG.sup.2 is a suitable amine protecting group, under amide forming conditions to form the compound of formula 18 or a salt thereof.

10. (canceled)

11. A process for preparing a compound of formula 17 as defined in claim 9, the process comprising removing the protecting group from the secondary amine of a compound of formula 15 ##STR00273## or a salt thereof, wherein: R.sup.3 is a substituted or unsubstituted ring selected from aryl and heteroaryl; and PG.sup.1 and PG.sup.3 are independently suitable amine protecting groups, under suitable conditions to remove the protecting group from the secondary amine of the compound of formula 15 to form the compound of formula 17 or a salt thereof.

12. (canceled)

13. A process for preparing a compound of formula 15 as defined in claim 11, the process comprising adding a protecting group to the primary amine of a compound of formula 14 ##STR00274## or a salt thereof, wherein: R.sup.3 is a substituted or unsubstituted ring selected from aryl and heteroaryl; and PG.sup.3 is a suitable amine protecting group, under suitable conditions to add the protecting group to the primary amine of the compound of formula 14 to form the compound of formula 15 or a salt thereof.

14. (canceled)

15. A process for preparing a compound of formula 14 as defined in claim 13, the process comprising reducing the azide of a compound of formula 13 ##STR00275## or a salt thereof, wherein: R.sup.3 is a substituted or unsubstituted ring selected from aryl and heteroaryl; and PG.sup.3 is a suitable amine protecting group, under suitable conditions to reduce the azide of a compound of formula 13 to form the compound of formula 14 or a salt thereof.

16. (canceled)

17. A process for preparing a compound of formula 13 as defined in claim 15, the process comprising adding a protecting group to the carboxylic acid of a compound of formula 12 ##STR00276## or a salt thereof, wherein: PG.sup.3 is a suitable amine protecting group, under suitable conditions to add a protecting group to the carboxylic acid of a compound of formula 12 to form the compound of formula 13 or a salt thereof.

18. (canceled)

19. A process for preparing a compound of formula 12 as defined in claim 17, the process comprising treating a compound of formula 11 ##STR00277## or a salt thereof, wherein: each X is independently hydrogen or halogen; and PG.sup.3 is a suitable amine protecting group, under suitable conditions to convert the compound of formula 11 into the compound of formula 12 or a salt thereof.

20. (canceled)

21. A process for preparing a compound of formula 11 as defined in claim 19, the process comprising removing the protecting group from the tertiary alcohol of a compound of formula 10 ##STR00278## or a salt thereof, wherein: each X is independently hydrogen or halogen; PG.sup.3 is a suitable amine protecting group; and PG.sup.6 is a suitable hydroxyl protecting group, under suitable conditions to remove the protecting group from the tertiary alcohol of the compound of formula 10 to form the compound of formula 11 or a salt thereof.

22. (canceled)

23. A process for preparing a compound of formula 10 as defined in claim 21, the process comprising treating a compound of formula 9 ##STR00279## or a salt thereof, wherein: PG.sup.3 is a suitable amine protecting group, under suitable conditions to alkylate the compound of formula 9 to form the compound of formula 10 or a salt thereof.

24. (canceled)

25. A process for preparing a compound of formula 9 as defined in claim 23, the process comprising oxidizing the secondary alcohol of a compound of formula 8 ##STR00280## or a salt thereof, wherein: PG.sup.3 is a suitable amine protecting group, under suitable conditions to oxidize the secondary alcohol of a compound of formula 8 to form the compound of formula 9 or a salt thereof.

26. (canceled)

27. A process for preparing a compound of formula 8 as defined in claim 25, the process comprising removing the protecting group from the secondary alcohol and the initial protecting group (PG.sup.N, if PG.sup.N is a suitable amine protecting group) from the secondary amine, and adding another protecting group to the secondary amine of a compound of formula 7 ##STR00281## or a salt thereof, wherein: PG.sup.4 is a suitable hydroxyl protecting group; and PG.sup.N is H or a suitable amine protecting group, under suitable conditions to remove the protecting group from the secondary alcohol and the initial protecting group (PG.sup.N, if PG.sup.N is a suitable amine protecting group) from the secondary amine, and adding another protecting group to the secondary amine of a compound of formula 7 to form the compound of formula 8 or a salt thereof.

28. (canceled)

29. A process for preparing a compound of formula 7 as defined in claim 27, the process comprising treating a compound of formula 6 ##STR00282## or a salt thereof, with H.sub.2N-PG.sup.N, wherein: LG is a suitable leaving group; PG.sup.4 is a suitable hydroxyl protecting group; and PG.sup.N is H or a suitable amine protecting group, under suitable conditions to perform a double displacement reaction on the compound of formula 6 to form the compound of formula 7 or a salt thereof.

30. (canceled)

31. A process for preparing a compound of formula 6 as defined in claim 29, the process comprising converting the primary alcohols of a compound of formula 5 ##STR00283## or a salt thereof, wherein: PG.sup.4 is a suitable hydroxyl protecting group, into leaving groups under suitable conditions to form the compound of formula 6 or a salt thereof.

32. (canceled)

33. A process for preparing a compound of formula 5 as defined in claim 31, the process comprising reducing the alkyl carboxylates of a compound of formula 4 ##STR00284## or a salt thereof, wherein: each R.sup.4 is independently (C.sub.1-C.sub.6)alkyl; PG.sup.4 is a suitable hydroxyl protecting group, under suitable conditions to reduce the alkyl carboxylates of the compound of formula 4 to form the compound of formula 5 or a salt thereof.

34. (canceled)

35. A process for preparing a compound of formula 4 as defined in claim 33, the process comprising adding a protecting group to the secondary alcohol of a compound of formula 3 ##STR00285## or a salt thereof, wherein: each R.sup.4 is independently (C.sub.1-C.sub.6)alkyl; under suitable conditions to form the compound of formula 4 or a salt thereof.

36. (canceled)

37. A process for preparing a compound of formula 3 as defined in claim 35, the process comprising allylating a compound of formula 2 ##STR00286## or a salt thereof, wherein: each R.sup.4 is independently (C.sub.1-C.sub.6)alkyl; under suitable conditions to allylate the compound of formula 2 to form the compound of formula 3 or a salt thereof.

38. (canceled)

39. A process for preparing a compound of formula 2 as defined in claim 37, the process comprising esterifying L-malic acid under suitable conditions to form the compound of formula 2 or a salt thereof.

40. (canceled)

41. A process for preparing a compound of formula 9 as defined in claim 23, the process comprising oxidizing the secondary alcohol of a compound of formula 8b ##STR00287## or a salt thereof, wherein: PG.sup.3 is a suitable amine protecting group, under suitable conditions to form the compound of formula 9 or a salt thereof.

42. (canceled)

43. A process for preparing a compound of formula 8b as defined in claim 41, the process comprising diastereoselective enzymatic reduction of a compound of formula 7b ##STR00288## or a salt thereof, wherein: PG.sup.3 is a suitable amine protecting group, under suitable conditions to form the compound of formula 8b or a salt thereof.

44-63. (canceled)

64. A compound of formula 20 ##STR00289## or a salt thereof, wherein: R.sup.2 is H, (C.sub.1-C.sub.6)alkyl, —CH.sub.2OZ, —CH(CH.sub.3)OZ, —CH.sub.2SZ, —(CH.sub.2).sub.2SCH.sub.3, —CH.sub.2CONZ.sub.2, —(CH.sub.2).sub.2CONZ.sub.2, —CH.sub.2CO.sub.2Z, —(CH.sub.2).sub.2CO.sub.2Z, —(CH.sub.2).sub.4NZ.sub.2, ##STR00290## each Z is independently H, (C.sub.1-C.sub.6)alkyl, or a suitable protecting group; R.sup.3 is a substituted or unsubstituted ring selected from aryl and heteroaryl; and PG.sup.1 and PG.sup.2 are independently suitable amine protecting groups.

65. (canceled)

66. A compound of formula 19 ##STR00291## or a salt thereof, wherein: each R is independently (C.sub.1-C.sub.6)alkyl, or: two R groups are optionally taken together with their intervening atoms to form a substituted or unsubstituted monocyclic or bicyclic ring selected from a saturated or partially unsaturated heterocycle; R.sup.2 is H, (C.sub.1-C.sub.6)alkyl, —CH.sub.2OZ, —CH(CH.sub.3)OZ, —CH.sub.2SZ, —(CH.sub.2).sub.2SCH.sub.3, —CH.sub.2CONZ.sub.2, —(CH.sub.2).sub.2CONZ.sub.2, —CH.sub.2CO.sub.2Z, —(CH.sub.2).sub.2CO.sub.2Z, —(CH.sub.2).sub.4NZ.sub.2, ##STR00292## each Z is independently H, (C.sub.1-C.sub.6)alkyl, or a suitable protecting group; R.sup.3 is a substituted or unsubstituted ring selected from aryl and heteroaryl: and PG.sup.1 and PG.sup.2 are independently suitable amine protecting groups.

67. (canceled)

68. A compound of formula 18 ##STR00293## or a salt thereof, wherein: R.sup.2 is H, (C.sub.1-C.sub.6)alkyl, —CH.sub.2OZ, —CH(CH.sub.3)OZ, —CH.sub.2SZ, —(CH.sub.2).sub.2SCH.sub.3, —CH.sub.2CONZ.sub.2, —(CH.sub.2).sub.2CONZ.sub.2, —CH.sub.2CO.sub.2Z, —(CH.sub.2).sub.2CO.sub.2Z, —(CH.sub.2).sub.4NZ.sub.2, ##STR00294## each Z is independently H, (C.sub.1-C.sub.6)alkyl, or a suitable protecting group; R.sup.3 is a substituted or unsubstituted ring selected from aryl and heteroaryl; and PG.sup.1 and PG.sup.2 are independently suitable amine protecting groups.

69. (canceled)

70. A compound of formula 17 ##STR00295## or a salt thereof, wherein: R.sup.3 is a substituted or unsubstituted ring selected from aryl and heteroaryl; and PG.sup.1 is a suitable amine protecting group.

71. (canceled)

72. A compound of formula 15 ##STR00296## or a salt thereof, wherein: R.sup.3 is a substituted or unsubstituted ring selected from aryl and heteroaryl; and PG.sup.1 and PG.sup.3 are independently suitable amine protecting groups.

73. (canceled)

74. A compound of formula 14 ##STR00297## or a salt thereof, wherein: R.sup.3 is a substituted or unsubstituted ring selected from aryl and heteroaryl; and PG.sup.3 is a suitable amine protecting group.

75. (canceled)

76. A compound of formula 13 ##STR00298## or a salt thereof, wherein: R.sup.3 is a substituted or unsubstituted ring selected from aryl and heteroaryl; and PG.sup.3 is a suitable amine protecting group.

77-83. (canceled)

84. A compound of formula 20c ##STR00299## or a salt thereof, wherein: R.sup.2 is H, (C.sub.1-C.sub.6)alkyl, or —CH.sub.2OH; and PG.sup.1 and PG.sup.2 are independently suitable amine protecting groups.

85-94. (canceled)

Description

4. EXAMPLES

[0637] This section will describe the various different working examples that will be used to highlight the features of the present disclosure.

[0638] The starting materials and reagents used in the preparation of the compounds in the present disclosure are either available from commercial suppliers such as Sigma-Aldrich (St. Louis, Mo.) or Fisher Scientific (Hampton, N.H.) or are prepared by methods known to those skilled in the art following procedures set forth in references such as Fieser and Fieser's Reagents for Organic Synthesis, Volumes 1-17 (John Wiley and Sons, 1991), Organic Reactions, Volumes 1-40 (John Wiley and Sons, 1991), and March's Advanced Organic Chemistry (John Wiley and Sons, 4.sup.th Edition).

Example 1: Synthesis of (3R,4S)-3-benzyl 1-tert-butyl 4-allyl-3-(benzyloxycarbonylamino)pyrrolidine-1,3-dicarboxylate from L(−)-malic Acid

[0639] ##STR00250## ##STR00251##

[0640] All yields for the synthesis of 5-12 are considered crude and uncorrected.

[0641] Step 1: (S)-Diethyl 2-hydroxysuccinate (5-1). To an inerted reactor was charged ethanol (2400 kg). Agitation was started and upon cooling to 0±10° C., acetyl chloride (708 kg, 9,000 mol) was added slowly over the course of approx. 5 hrs. Next, L(−)-malic acid (600 kg, 4,470 mol) was charged to the mixture while maintaining the batch between −10 to −20° C. The mixture was then warmed to 23-27° C. and stirred for 18 hrs after which the starting material was deemed consumed by TLC. The batch was then concentrated under reduced pressure and the residue was diluted with DCM (1050 kg) and water (900 kg). After agitating for 15 min., agitation was stopped and the phases were separated. The aqueous phase was back-extracted with DCM (600 kg). The organic phases were combined and washed with 8% aqueous sodium bicarbonate (1100 kg) and 20% brine (600 kg). After drying over Na.sub.2SO.sub.4 (174 kg), the batch was filtered and concentrated under reduced pressure. THF (250 kg) was charged to the residue and the solution was evaporated to dryness to afford 5-1 as yellow oil (569 kg, 66.9% yield, 93% purity) which was used without further purification.

[0642] Step 2: (2R,3S)-Diethyl 2-allyl-3-hydroxysuccinate (5-2). To an inerted reactor was charged THF (855 kg) and HMDS (320 kg, 1.98 mol) at ambient temperature. Agitation was started and the mixture was cooled to about −70° C. At this temperature, 2.5M n-BuLi (500 kg, 1843 Mol) was added slowly while the temperature was maintained at −60±5° C. The mixture was stirred for 0.5 h at this temperature. Next, a solution of 5-1 (171 kg) from the previous step in THF (171 kg) was added slowly while the temperature was maintained at −60±5° C. The mixture was stirred for 1.0 h at this temperature. Next allyl bromide (163.3 kg, 1349 mol) was added slowly while the temperature was being maintained at −60±5° C. The mixture was stirred for 1.0 h after addition and warmed to 10±5° C. After stirring for 2 hrs at this temperature, the reaction was deemed complete by HPLC. The mixture was then quenched by slow addition of aqueous 20% citric acid (1400 kg) keeping the temperature below 15° C. The mixture was agitated for 15 min and upon ceasing agitation, the phases were separated. The aqueous phase was back-extracted with MTBE (513 kg) and the combined organic phases were washed with 10% brine (496 kg). After being dried with Na.sub.2SO.sub.4 (50 kg), the solution was concentrated to dryness to afford crude (2R,3S)-diethyl 2-allyl-3-hydroxysuccinate (5-2) as a yellow oil (192.0 kg, 92.7% yield, ˜9:1 mixture of diastereoisomers, 75.6% purity), which was used without further purification in the next step.

[0643] Step 3: (2R,3S)-Diethyl 2-allyl-3-(tetrahydro-2H-pyran-2-yloxy)succinate (5-3). To a reactor was charged dichloromethane (2100 kg), crude (2R,3S)-diethyl 2-allyl-3-hydroxysuccinate (5-2) (700 kg, 75.6% purity), dihydropyran (384 kg, 4561 mol) and PPTS (21 kg, 83.6 mol). Agitation was started and the mixture was heated to 35±3° C. and stirred for 8 hrs after which it was deemed complete by HPLC. The mixture was then cooled to 20±10° C. Next water (1400 kg) was added and the organic layer was separated. The aqueous phase was then back-extracted with DCM (1400 kg) and the combined organic phases were washed with 10% brine (700 kg), dried over Na.sub.2SO.sub.4 (50 kg) and filtered. The filtrate was evaporated to dryness under reduced pressure to afford crude 5-3 (1032.1 kg, 99.3% yield, 75.3% purity) as a yellow oil which was used in the next step without further purification.

[0644] Step 4: (2S,3S)-2-Allyl-3-(tetrahydro-2H-pyran-2-yloxy)butane-1,4-diol (5-4). To an inerted reactor was charged toluene (720 kg) and 70% Red-Al® in toluene (826 kg) under nitrogen. Agitation was started and the mixture was cooled to 0-10° C. A solution of (2R,3S)-diethyl 2-allyl-3-(tetrahydro-2H-pyran-2-yloxy)succinate (5-3) (360 kg, 75.3% purity) in toluene (360 kg) was added slowly while maintaining the temperature between 0-10° C. After the addition, the mixture was warmed to 20-30° C. and stirred for 4 hrs and the reaction was deemed complete by HPLC. The reaction mixture was then added to a solution of potassium sodium tartrate (1616 kg) in water (2412 kg) and the organic layer was separated after agitation. The aqueous phase was back-extracted with MTBE twice (2×720 kg). The combined organic phases were washed with 25% brine (504 kg). The aqueous phase was back-extracted with MTBE (360 kg). The organic phases were combined, dried over Na.sub.2SO.sub.4 (50 kg) and filtered. The filtrate was concentrated to afford 5-4 (227.4 kg, 87.4% yield, 88.7% purity) as a yellow oil which was used directly for the next step.

[0645] Step 5: (2S,3S)-2-Allyl-3-(tetrahydro-2H-pyran-2-yloxy)butane-1,4-diyl dimethanesulfonate (5-5). To a reactor was charged crude (2S,3S)-2-allyl-3-(tetrahydro-2H-pyran-2-yloxy)butane-1,4-diol (5-4). (332 kg, 88.7% purity), Et3N (486 kg, 4812 mol) and dichloromethane (1476 kg). Agitation was started and the mixture was cooled to 0±10° C. At this temperature, methanesulfonyl chloride (441 kg, 3851 mol) was added slowly over the course of approx. 12 hrs. The mixture was warmed to 15-25° C. and stirred for 1 h at this temperature. No starting material was detected by TLC. The mixture was quenched by slow addition to water (996 kg), keeping the internal temperature below 15° C. Agitation of the mixture was continued for 15 min and the phases were separated. The aqueous phase was back-extracted with DCM (738 kg). The combined organic phase was washed with 20% brine (664 kg). After being dried with Na.sub.2SO.sub.4 (45 kg), the batch was concentrated under reduced pressure to afford crude 5-5 (527.7 kg, 94% yield) as a brown oil which was used directly for the next step without further purification.

[0646] Step 6: (3S,4S)-3-Allyl-1-benzyl-4-(tetrahydro-2H-pyran-2-yloxy)pyrrolidine (5-6). To a reactor was charged diisopropylethylamine (530.1 kg, 4108 mol), crude (2S,3S)-2-allyl-3-(tetrahydro-2H-pyran-2-yloxy)butane-1,4-diyl dimethanesulfonate (5-5) (527.7 kg) from the previous step and benzylamine (292.3 kg, 2728 mol). The mixture was agitated and heated to 55-65° C. for 2 hrs. Next, the mixture was heated to 97-99° C. and stirred for 7 hrs where TLC showed no starting material. The mixture was allowed to cool to 10-30° C. Next, CH.sub.3CN (528 kg) and Et.sub.3N (276 kg, 2727 mol) were added to the reaction mixture, followed by addition of succinic anhydride (178 kg, 1775 mol) over the course of 2 hrs while the internal temperature was being maintained at 15-30° C. The mixture was stirred for 2 hrs at this temperature until benzylamine was consumed. The batch was next concentrated under reduced pressure. A solution of Na.sub.2CO.sub.3 (1.0 eq) in water (1056 kg) was then added slowly while maintaining the temperature between 10-25° C. The mixture was next diluted with MTBE (1056 kg). Agitation of the mixture was continued for 15 min and the phases were separated. The aqueous phase was back-extracted with MTBE (528 kg). The combined organic phases were washed with a solution of Na.sub.2CO.sub.3 (144 kg) in water (972 kg) and 10% brine (1056 kg). After being dried with Na.sub.2SO.sub.4 (50 kg), the batch was filtered. The filtrate was concentrated under reduced pressure to afford crude 5-6 (369.5 kg, 89.8% yield, 90.7% purity) as a brown oil which was used without further purification in the next step.

[0647] Step 7: (3S,4S)-tert-Butyl 3-allyl-4-hydroxypyrrolidine-1-carboxylate (5-7). To a reactor was charged dichloromethane (1536 kg) and 1-chloroethyl chloroformate (273 kg, 1906 mol) under nitrogen and at ambient temperature. Agitation was started and the mixture was cooled to between −8 and −11° C. Diisopropylethylamine (49.4 kg, 383 mol) was added slowly while the temperature was being maintained between −8 and −11° C. The mixture was stirred for 5 mins at this temperature. Next a solution of crude 5-6 (384 kg) in DCM (384 kg) was added slowly while the temperature was being maintained between −8 and −11° C. After the addition, the mixture was warmed to NMT 20° C. and stirred for 1 h at this temperature. Upon consumption of starting material, the reaction mixture was added to MeOH (1536 kg) while the temperature was being maintained between 5 and 25° C. The batch was stirred for 8 hrs at this temperature and then concentrated under reduced pressure. The residue was diluted with MTBE (768 kg) and water (1920 kg). The mixture was agitated for 15 min and the phases were separated. The aqueous phase was back-extracted with MTBE (768 kg) and then a solution of Na.sub.2CO.sub.3 (406 kg) in water (1574 kg) was added slowly while the temperature was being maintained between 10 and 25° C. A solution of Boc anhydride (277 kg, 1271 mol) in THF (384 kg) was added slowly while maintaining the temperature between 0 and 10° C. The mixture was warmed to ambient temperature and stirred for 8 hrs. The mixture was next diluted with MTBE (768 kg) and water (3000 kg). Agitation of the mixture continued for 15 min and ceased wherein the phases were separated. The aqueous phase was then back-extracted with MTBE (768 kg). The combined organic phases were washed with 10% brine (768 kg). After being dried with Na.sub.2SO.sub.4 (50 kg), the batch was concentrated under reduced pressure to give a brown solid. The brown solid was suspended in petroleum ether (768 kg) and heated to 50-60° C. until a solution was obtained. The solution was allowed to cool slowly to 40° C. under agitation and aged for 2 hrs at this temperature. The slurry was further cooled to 10-15° C. and the solids were collected by filtration. The filter cake was rinsed with cold petroleum ether (384 kg) to give 5-7 (158.5 kg, 55.1% yield, 99.3% purity) as a yellow solid.

[0648] Step 8: (S)-tert-butyl 3-allyl-4-oxopyrrolidine-1-carboxylate (5-8). To a reactor was charged DCM (670 kg) and oxalyl chloride (7.3 kg, 57.5 mol) under nitrogen. Agitation was started and the mixture was cooled to between −60 and −65° C. At this temperature, a solution DMSO (5.2 kg. 66.6 mol) in dichloromethane (13 kg) was added slowly while maintaining the temperature between at −54 and −65° C. The mixture was stirred for 0.5 h at this temperature. A solution of 5-7 (10 kg) in dichloromethane (27 kg) was added slowly while maintaining the temperature being between −54 and −65° C. The mixture was stirred for 1.0 h at this temperature. Diisopropylethyl amine was added slowly while maintaining the temperature being between −54 and −65° C. Next, the mixture was stirred for 1.0 h at this temperature and warmed to about −30° C. The reaction was stirred for 2.0 h at this temperature and deemed complete by HPLC. The reaction solution was next charged to a mixture citric acid monohydrate (4.6 kg) and water (50 kg). The organic layer was separated and the aqueous layer extracted with DCM (66 kg). The DCM extracts were combined and washed successively with a solution of citric acid monohydrate (2.7 kg) in H.sub.2O (50 kg), H.sub.2O (30 kg×4), 10% brine (20 kg). After drying with Na.sub.2SO.sub.4 (10 kg), the solution was concentrated to 2.5V. Next, THF (18 kg) was added to the reactor followed by concentrating the solution to 2V. THF (18 kg) was added again to the reactor and the solution was concentrated to 2V to afford 5-8 (80.6% purity, 97.8% ee) in THF which was used directly for the next reaction.

[0649] Step 9: (3S,4S)-tert-Butyl 4-allyl-3-(trichloromethyl)-3-(trimethylsilyloxy)pyrrolidine-1-carboxylate (5-9). To a reactor was charged THF (14.4 kg), DMF (14.4 kg) and TMSCCl.sub.3 (12.8 kg, 66.8 mol) under nitrogen. Agitation was started and the mixture was cooled to about −20° C. At this temperature, the solution of 5-8 in THF from the previous step was added slowly while maintaining the temperature between −25 and −20° C. After the addition, a solution of tetrabutylammonium acetate (1.4 kg, 4.6 mol) in DMF (14.4 kg) was added slowly while the temperature being maintained between −25 and −20° C. The reaction mixture was stirred for 1 h at this temperature or until starting material was consumed. The reaction solution was charged to a mixture of sat. NH.sub.4Cl (128 kg) and MTBE (74 kg) with agitation. After agitation stopped, the organic layer was separated and the aqueous layer back-extracted with MTBE (37 kg). The organic extracts were combined and washed twice with H.sub.2O (60 kg total). After being dried with Na.sub.2SO.sub.4 (15 kg), the solution was concentrated to dryness to afford 5-9 (60.3% purity) as a brown oil which was used directly in the next step.

[0650] Step 10: (3S,4S)-tert-Butyl 4-allyl-3-hydroxy-3-(trichloromethyl)pyrrolidine-1-carboxylate (5-10). To an inerted reactor was charged THF (26.7 kg) and 5-9 from the previous reaction. The mixture was agitated and cooled to between 0 and 10° C. At this temperature, a solution of TBAF (14.4 kg, 453 mol) and AcOH (2.7 kg, 453 mol) in THF (18 kg) was added slowly while the temperature was kept between 0 and 10° C. The reaction mixture was stirred at this temperature for 1 h and deemed complete by HPLC. The mixture was then added to an aqueous solution of NaHCO.sub.3 (4.2 kg, 500 mol) in H.sub.2O (50 kg) and ethyl acetate (45.1 kg). The organic layer was separated and the aqueous layer extracted twice with EA (50 kg total). The organic layers were combined and washed twice with half sat. brine (47 kg) and sat. brine (27 kg). After being dried with Na.sub.2SO.sub.4 (38 kg), the solution was concentrated to dryness. The residue was dissolved in PE (54 kg) and EA (5.7 kg). The mixture was warmed until most of solid dissolved. The solution was cooled slowly to 0° C. and filtered. The cake was dried under reduced pressure to afford 5-10 (11.2 kg, 74% based on 5-7, 98.8% purity, 100% ee), as an off-white solid.

[0651] Step 11: (3R,4S)-4-allyl-3-azido-1-(tert-butoxycarbonyl)pyrrolidine-3-carboxylic acid (5-11). To an inerted reactor was charged 1,4-dioxane (44.5 kg) and (3S,4S)-tert-Butyl 4-allyl-3-hydroxy-3-(trichloromethyl)pyrrolidine-1-carboxylate 5-10 (11 kg) from the previous reaction. Agitation was started and the mixture was cooled to between 8-13° C. At this temperature, a solution NaN.sub.3 (3.1 kg, 47.7 mol), NaOH (3.8 kg, 95 mol) in H.sub.2O (44 kg) was added slowly while the temperature was being maintained between 10-15° C. Agitation was continued for 1 h. The reaction solution was then warmed to about 20° C. and stirred for 1 h. The reaction solution was then warmed to 25-32° C. and stirred for 2 hrs and deemed complete by HPLC. The mixture was next added to sat. aq. NH.sub.4Cl (33.3 kg) and ethyl acetate (49.5 kg). The organic layer was separated and the aqueous layer back-extracted twice with ethyl acetate (99 kg total). The organic layers were combined and washed twice with half sat. brine (52 kg total). The aqueous layer was next back-extracted with EA (30 kg). The organic layers were combined and washed with aqueous citric acid monohydrate (7.3 kg) in H.sub.2O (36.3 kg). The organic layer was separated and washed with sat. brine (30 kg). After being dried with Na.sub.2SO.sub.4 (11 kg), the solution was concentrated to dryness to afford 5-11 as a yellow oil and used directly in the next step.

[0652] Step 12: (3R,4S)-3-benzyl 1-tert-butyl 4-allyl-3-azidopyrrolidine-1,3-dicarboxylate (5-12). To a reactor were charged DMF (26.9 kg) and (3R,4S)-4-allyl-3-azido-1-(tert-butoxycarbonyl)pyrrolidine-3-carboxylic acid (5-11) from the previous reaction. Next, K.sub.2CO.sub.3 (3.6 kg, 28.6 mol) was added to the reaction solution while the temperature being kept at 15-30° C., followed by addition of BnBr (4.9 kg, 28.6 mol). After the addition, the reaction mixture was heated to 35-45° C. Agitation was continued at 35-45° C. for 4 hrs where the reaction was deemed complete by HPLC. The reaction mixture was then charged to a mixture of MTBE (35.8 kg) and H.sub.2O (47 kg) while maintaining the temperature between 0 and 10° C. The organic layer was separated and the aqueous layer extracted with MTBE twice (36 kg total). The MTBE extracts were combined and washed with H.sub.2O (38 kg). After being dried with Na.sub.2SO.sub.4 (5.6 kg), the solution was concentrated to dryness to afford 5-12 (9.4 kg, 76.4% yield based on 5-10, 89.4% purity) as a yellow oil which was used directly in the next reaction.

[0653] Step 13: (3R,4S)-3-benzyl 1-tert-butyl 4-allyl-3-aminopyrrolidine-1,3-dicarboxylate (5-13). To an inerted reactor was charged THF (34 kg), AcOH (39.5 kg) and crude (3R,4S)-3-benzyl 1-tert-butyl 4-allyl-3-azidopyrrolidine-1,3-dicarboxylate (5-12) from the previous reaction. Agitation was started and the mixture was heated to between 38-42° C. Zinc powder (3.4 kg, 52 mol) was added to the mixture while the reaction temperature was being maintained between 59±3° C. At this temperature, the reaction mixture was stirred for 1 h after which it was deemed complete. The mixture was filtered and the filter cake washed with THF (3.8 kg). The filtrate was evaporated and to the residue was charged MTBE (35.7 kg) and H.sub.2O (37.6 kg). The pH of the reaction mixture was brought up to 8 by addition of NH.sub.4OH. The organic layer was separated and the aqueous layer extracted with MTBE twice (42 kg total). The organic layers were combined and washed twice with H.sub.2O (18.9 kg total). After being dried with Na.sub.2SO.sub.4 (7.5 kg), the solution was concentrated to dryness. To the resulting residue was charged acetonitrile (58.8 kg) and the batch was heated to between 55-68° C. A solution of L(+)-tartaric acid (3.65 kg, 24.3 mol) in THF (44 kg) was added to the mixture while the temperature was between 55-65° C. After the addition, the batch was cooled to 0° C. and stirred for 0.5 h. The suspension was filtered and the solids were washed with MeCN (15 kg). The wet cake was charged to a mixture of MTBE (28.2 kg) and H.sub.2O (28.2 kg). The pH of the mixture was brought to 8 by addition of NaHCO.sub.3 (4.2 kg, 50 mol). The organic layer was separated and the aqueous layer extracted twice with MTBE (35 kg total). The organic extracts were combined and washed twice with H.sub.2O (18.8 kg total). After being dried with Na.sub.2SO.sub.4 (7.5 kg), the filtered solution was concentrated to dryness to afford 5-13 as a colorless to light yellow oil which was used directly in the next reaction.

[0654] Step 14: (3R,4S)-3-benzyl 1-tert-butyl 4-allyl-3-(benzyloxycarbonylamino)pyrrolidine-1,3-dicarboxylate (5-14). To an inerted reactor was charged THF (31.5 kg), 5-13 from the previous reaction, H.sub.2O (35 kg), NaHCO.sub.3 (0.5 kg) and Cbz-OSu (4.85 kg). Agitation was started and the mixture was heated to 35-40° C. Agitation was continued at 35-40° C. for 8 hrs where the reaction was deemed complete. The reaction mixture was cooled to 20±10° C. NaHCO.sub.3 (1.6 kg) was added slowly to the mixture, followed by EA (28 kg). The organic layer was separated and the aqueous layer extracted with ethyl acetate (31.5 kg). The organic layers were combined and washed with 5% aqueous NaHCO.sub.3 (14.7 kg), half sat. brine (25 kg) and sat. brine (19 kg). After being dried with Na.sub.2SO.sub.4 (7. Kg), the solution was concentrated to dryness. Next MeCN (16.8 kg) was charged. The mixture was heated to 60-81° C. and H.sub.2O (28 kg) was added. The solution was cooled slowly to about 0° C. and filtered. The wet cake was washed with a mixture of MeCN (4.97 kg) and H.sub.2O (8.4 kg). The wet cake was suspended in MeCN (17 kg) and the mixture was heated to 70±10° C. and H.sub.2O (28 kg) was added. The solution was cooled slowly to about 0° C. and filtered. The filter cake was washed with a mixture of MeCN (5 kg) and H.sub.2O (8.4 kg). The cake was dried under reduced pressure at about 55° C. to afford 5-14 as white solid (8.96 kg, 56.8% yield based on 5-10 initial charge of 11 kg, 99% purity, greater than 99.95% ee. .sup.1H NMR (500 MHz, DMSO) δ 8.26 (d, J=10.1 Hz, 1H), 7.46-7.30 (m, 10H), 5.74-5.52 (m, 1H), 5.23-5.08 (m, 2H), 5.08-4.95 (m, 4H), 4.18 (d, J=11.4 Hz, 1H), 3.47 (dd, J=10.7, 7.5 Hz, 1H), 3.38-3.24 (m, 1H), 2.95 (dt, J=10.9, 7.7 Hz, 1H), 2.48-2.36 (m, 1H), 2.36-2.23 (m, 1H), 1.58 (dt, J=12.0, 6.3 Hz, 1H), 1.38 (s, 9H); HRMS (ESI.sup.+): [M+Na].sup.+ calc. m/z=517.2309, found m/z=517.2315.

Example 2: Alternate Synthesis of (3R,4S)-3-benzyl 1-tert-butyl 4-allyl-3-(benzyloxycarbonylamino)pyrrolidine-1,3-dicarboxylate Starting from diethyl (2S,3S)-2,3-dihydroxysuccinate

[0655] ##STR00252## ##STR00253##

[0656] Step 1: Diethyl D-tartrate (6-1). To a three-necked flask was added anhydrous EtOH (5V) under nitrogen. Next, acetyl chloride (2.0 eq) was added dropwise at −10 to 10° C., followed by D-tartaric acid (1.0 eq). The reaction temperature was raised to 23-27° C. and maintained at that temperature for 18 hours after which the reaction was deemed complete. The mixture was then concentrated to dryness. Next, dichloromethane (5V) was added with agitation, followed by water (5V). After stopping agitation, the phases were separated. The organic phase was washed with a sodium bicarbonate solution and a 20% sodium chloride solution and the solvent was removed to afford the titled 6-1 as a yellow oil (75.8% yield) used without further purification in the next step.

[0657] Step 2: Diethyl (4S,5S)-2-ethoxy-1,3-dioxolane-4,5-dicarboxylate (6-2). To a flask was added 6-1 (1.0 eq), triethyl orthoformate (2.7 eq), p-toluenesulfonic acid (0.01 eq) and toluene (4V). The reaction mixture was heated to 100-110° C. Ethanol was removed by distillation with a Dean-Stark trap for 8 hours and toluene was replenished until completion by TLC. The reaction mixture was cooled to room temperature and washed with a NaHCO.sub.3 solution (2V). The organic phase was concentrated to dryness to afford the titled 6-2 (99.8% yield, GC 95.9% purity) and used without further purification in the next step.

[0658] Step 3: ((4R,5R)-2-Ethoxy-1,3-dioxolane-4,5-diyl)dimethanol (6-3). To a flask was added LiAlH.sub.4 (1.0 eq) and THF (6V) under nitrogen. The mixture was cooled to 0° C. with an ice-salt bath. 6-2 (1.0 eq) was added dropwise and the reaction temperature was maintained at 0-10° C. After the addition was completed, the reaction mixture was stirred at 25° C. for 1 hour and shown to be complete by TLC. The reaction mixture was cooled to 0° C. Na.sub.2SO.sub.4.10H.sub.2O was next added in portions and the temperature was maintained 0-10° C. After the addition, the reaction mixture was stirred at room temperature for 1 hour and filtered. The solvent in the filtrate was removed to afford the titled 6-3 as an oil (73% yield, 90.1% GC purity).

[0659] Step 4: (4R,5R)-4,5-Bis((benzyloxy)methyl)-2-ethoxy-1,3-dioxolane (6-4). THF (4V), DMF (1V), and NaH (2.5 eq) were added to a flask under nitrogen. The mixture was then cooled to 0° C. Next a solution of 6-3 (1.0 eq) in THF (1V) was added dropwise. After the addition, the reaction mixture was allowed to stir at room temperature for 1 hour. The reaction mixture was then cooled to 0° C. and benzyl chloride (2.5 eq) was added drop wise at 0-10° C. After the addition, the reaction mixture was stirred at room temperature overnight. Upon completion, the reaction was quenched by adding the mixture to a NaHCO.sub.3 solution. The mixture was then extracted with methyl t-butyl ether twice. The combined organic phase was washed with water, followed by saturated brine. The organic phase was then dried with anhydrous Na.sub.2SO.sub.4 and filtered. The solvent was removed to afford the titled 6-4 as an oil (107% yield containing unreacted BnCl).

[0660] Step 5: (2R,3S)-1,4-Bis(benzyloxy)-3-chlorobutan-2-yl formate (6-5). To a flask was added CH.sub.2Cl.sub.2 (4V) and PCl.sub.5 (1.2 eq) under nitrogen. Next, a solution of 6-4 (1.0 eq) in DCM (1V) was added dropwise and the temperature was maintained at 0-10° C. The mixture was cooled to 0° C. After the addition, the reaction mixture was stirred at room temperature overnight. Upon completion, the reaction was quenched by adding the mixture to a NaHCO.sub.3 solution. After phase separation, the organic phase was washed with a NaHCO.sub.3 solution and a saturated NaCl solution. The organic phase was dried with anhydrous Na.sub.2SO.sub.4 and filtered. The filtrate was concentrated to afford the titled 6-5 as an oil (92.4% yield) which was used without further purification in the next step.

[0661] Step 6: (2R,3R)-2,3-Bis((benzyloxy)methyl)oxirane (6-6). Methanol (5V), 6-5 (1.0 eq), and K.sub.2CO.sub.3 (3.0 eq) were added to a flask. The mixture was stirred at room temperature overnight. Upon completion, the reaction mixture was concentrated to remove most of the methanol. Water (5V) was added and the mixture was extracted with MTBE (2V x 2). The combined organic phase was washed once with water and once with saturated brine. The organic phase was dried with anhydrous Na.sub.2SO.sub.4 and then filtered. After removal of the solvent, the residue was dissolved in petroleum ether (2V) and cooled to −50° C. A precipitate was observed, collected by filtration and dried to afford the titled 6-6 as a light-yellow solid (61.2% yield, 95.2% GC purity, 99.9% HPLC purity)

[0662] Step 7: (2S,3S)-1-(Benzyloxy)-3-((benzyloxy)methyl)hex-5-en-2-ol (6-7). To a flask was added a solution of allylmagnesium bromide (2.5 eq) in THF. The solvent was removed by distillation. Toluene (5V) was then added and the solvent was again removed by distillation. Toluene (5V) was added under nitrogen and the reaction mixture was cooled to 0° C. A solution of 6-6 (1.0 eq) in toluene (1V) was added dropwise and the reaction temperature was maintained at −5 to 5° C. After the addition, the reaction mixture was stirred at that temperature for an additional 30 min was judged complete by HPLC. The reaction mixture was then added to a 20% NH.sub.4Cl solution. After phase separation, the aqueous phase was extracted with MTBE (10V). The combined organic phase was washed with water, dried with anhydrous Na.sub.2SO.sub.4 and filtered. The filtrate was concentrated to dryness to give the titled 6-7 as an oil (99% yield, 97.9% HPLC purity) which was used without further purification in the next step.

[0663] Step 8: 2-(((2S,3S)-1-(Benzyloxy)-3-((benzyloxy)methyl)hex-5-en-2-yl)oxy)tetrahydro-2H-pyran (6-8). DCM (3V), 3,4-dihydropyran (1.5 eq), 6-7 (1 eq) and PPTS (0.02 eq) were added to a flask and the mixture stirred at room temperature overnight. Upon completion, the reaction mixture was washed with a NaHCO.sub.3 solution. The aqueous layer was back extracted with DCM (3V) and the combined organic phase was washed with water (2V), dried with anhydrous Na.sub.2SO.sub.4 and filtered. The solvent was removed from the filtrate to afford the titled 6-8 as an oil (99.5% yield) which was used without further purification in the next step

[0664] Step 9: (2S,3S)-2-Allyl-3-((tetrahydro-2H-pyran-2-yl)oxy)butane-1,4-diol (6-9). To a flask was added THF (2V) and 6-8 (1.0 eq) under nitrogen. The mixture was cooled to −60° C. and ammonia (6V) was bubbled through the reaction mixture. Lithium wire (4.1 eq) was cut and added in portions while maintaining the reaction temperature at −60 to −50° C. Upon completion the reaction mixture was slowly warmed to room temperature to evaporate the ammonia. DCM (10V) and anhydrous Na.sub.2SO.sub.4 (2.0 wt) were added to the reaction mixture. After stirring, the mixture was filtered. The solids were rinsed with DCM and the filtrate was concentrated to dryness to afford the titled 6-9 as an oil (100% yield).

[0665] Step 10: (2S,3S)-2-Allyl-3-((tetrahydro-2H-pyran-2-yl)oxy)butane-1,4-diyl dimethanesulfonate (6-10). DCM (4V), 6-9 (1.0 eq), and Et.sub.3N (3.0 eq) were added to a flask under nitrogen. The mixture was cooled to 0° C. Next MsCl (2.4 eq) was added dropwise while the reaction temperature was maintained at 0-10° C. The reaction mixture was then stirred at room temperature for 1 hour after the addition. After completion, the reaction mixture was added to ice water (5V). The phases were separated and the water phase was back extracted with DCM (4V). The combined organic phase was washed with water (5V). The organic phase was dried with anhydrous Na.sub.2SO.sub.4 and filtered. The solvent was removed from the filtrate to afford the titled 6-10 as an oil (100% yield) which was used without further purification in the next step.

[0666] Step 11: (3S,4S)-3-Allyl-4-((tetrahydro-2H-pyran-2-yl)oxy)pyrrolidine (6-11). To a chilled pressure vessel was added a 50% methanol solution (20V) and a solution of 6-10 (1.0 eq) in 1,4-dioxane (1V). The pressure vessel was closed and heated to 60° C. and kept at that temperature overnight. TLC showed incomplete reaction, LC-MS found the presence of a dimer as side product. After cooling, the solvent was evaporated and DCM (10V), added to the residue followed by a solution of Na.sub.2SO.sub.4. pH was adjusted to 13 with NaOH. The phases were then separated and the aqueous phase was back extracted with DCM. The combined organic phase was concentrated to afford the titled 6-11 as an oil (110% yield containing salts).

[0667] Step 12: tert-Butyl (3S,4S)-3-allyl-4-hydroxypyrrolidine-1-carboxylate (6-12). THF (5V), 6-11 (1.0 eq) from the previous reaction, water (10V), and hydrochloric acid (2.2 eq) were added to a flask and the mixture stirred at room temperature for 2 hours. TLC showed that the cyclization was complete. Next THF was removed and the reaction mixture was extracted with MTBE (5V×2). The organic phase was discarded. Sodium carbonate (3.0 eq) was then added to the aqueous phase. Next, a solution of (Boc).sub.2O (1.5 eq) in THF (5V) was added dropwise. The mixture was stirred at room temperature overnight. Upon completion, the reaction mixture was extracted with MTBE (5V×3) and the solvent was removed from the combined organic phases by distillation. The residue was dissolved in petroleum ether (5V) and stirred at room temperature to form a precipitate. The precipitate was collected by filtration and dried to afford the titled 6-12 as a while solid (28.3% yield, 100% ee, 97.6% HPLC purity). This material was shown to be identical to 5-7 made by a pilot batch via the malic acid route in Example 1.

Example 3: Alternate Synthesis of (S)-tert-butyl 3-allyl-4-oxopyrrolidine-1-carboxylate (5-8) Using Diastereoselective Enzymatic Reduction

[0668] ##STR00254##

[0669] Step 1: Cis/trans-tert-butyl 3-allyl-4-hydroxypyrrolidine-1-carboxylate (7-1). The NADP stock solution was prepared by adding 100 mL of 0.1 M pH 9 K.sub.2HPO.sub.4 solution to 20 mg of NADP, followed by 400 μL of 1M aqueous MgSO.sub.4. The KRED/NADP solution was prepared by adding 20 mL of NADP stock solution to 80 mg of KRED-208 (4 g/L KRED) (Codexis). To 10 mL of the KRED/NADP stock solution was added 2 g of racemic 5-8 in 10 mL of iPrOH to give a tan solution. The pH was measured to be 9. The solution was heated to 40° C. After 24h, the reaction was extracted with 40 mL of EtOAc. The organic phase was washed twice with water (10 mL total) and the organic layer was concentrated to dryness to give 7-1 (1.81 g, 90% yield, in 97:3 ratio favoring the (3S,4R)/trans isomer over the (3R,4R)/cis isomer. Immediate separation of diastereoisomers was not needed as diastereomeric enrichment occurs through successive crystallizations in later steps.

[0670] Step 2: (S)-tert-butyl 3-allyl-4-oxopyrrolidine-1-carboxylate (5-8). The titled compound was oxidized according the same procedure as described in Step 8 of Example 1.

Example 4: Synthesis of (6aS,9aR)-9a-amino-8-((S)-2-aminopropanoyl)-3-ethoxyoctahydro-[1,2]oxaborocino[7,6-c]pyrrol-1(3H)-one (8-5)

[0671] ##STR00255## ##STR00256##

[0672] Step 1: Benzyl (3R,4S)-4-allyl-3-(((benzyloxy)carbonyl)amino)pyrrolidine-3-carboxylate hydrochloride (8-1). To a jacketed reaction vessel containing 3-benzyl 1-(tert-butyl) (3R,4S)-4-allyl-3-(((benzyloxy)carbonyl)amino)pyrrolidine-1,3-dicarboxylate (5-14) (66.1 Kg, 134 mol) under a nitrogen atmosphere, was charged acetonitrile (MeCN) (396 L) and methyl tert-butyl ether (MTBE) (463 L). The white suspension was then stirred and subsequently cooled to 0-10° C. Then, 37% HCl in water (87.8 L, 1,050 mol) was added to the reaction mixture while maintaining the temperature range of 0-10° C. Once the addition was complete, the vessel was warmed to 15-25° C. and the reaction mixture was stirred for 8 hrs. Next, MTBE (463 L) was added to the reaction suspension and the vessel was subsequently cooled to 5-15° C. After stirring for 30 min at 5-15° C., the suspension was filtered, washing the vessel and filter cake with MTBE (132 L). The white solids were then dried at 40° C. to give 56.2 kg (97%) of 8-1. .sup.1H NMR (400 MHz, DMSO) δ 9.93 (s, 2H), 8.53 (s, 1H), 7.45-7.28 (m, 10H), 5.74-5.54 (m, 1H), 5.17 (s, 2H), 5.13-4.96 (m, 4H), 3.95 (d, J=12.5 Hz, 1H), 3.48-3.27 (m, 2H), 2.97 (dd, J=11.6, 7.8 Hz, 1H), 2.60-2.52 (m, 1H), 2.26-2.11 (m, 1H), 1.83-1.60 (m, 1H). .sup.13C NMR (126 MHz, DMSO) δ 170.32, 156.62, 136.80, 135.76, 135.32, 128.89, 128.87, 128.77, 128.49, 128.39, 118.29, 67.48, 66.95, 66.48, 52.66, 47.50, 44.92, 32.10. HRMS (ESI.sup.+): [M+H].sup.+ calc. m/z=395.1965, found m/z=395.1998.

[0673] Step 2: Benzyl (3R,4S)-4-allyl-1-(((benzyloxy)carbonyl)-L-alanyl)-3-(((benzyloxy)carbonyl)amino)pyrrolidine-3-carboxylate (8-2). To a vessel containing benzyl (3R,4S)-4-allyl-3-(((benzyloxy)carbonyl)amino)pyrrolidine-3-carboxylate HCl (56.2 kg, 130 mol, 8-1) and N-carbobenzyloxy-L-alanine (30.6 kg, 137 mol), under nitrogen, was charged ethyl acetate (EtOAc) (562 L). The suspension was stirred and subsequently cooled to 0-10° C. Next, triethylamine (63.3 L, 454 mol) was charged to the reaction vessel, followed by 50% 1-propanephosphonic anhydride solution (T.sub.3P) in ethyl acetate (133 L, 189 mol), while maintaining a batch temperature of 0-10° C. The reaction mixture was then warmed to 10-20° C. and agitated for 1h. Next, the suspension was cooled to 0-10° C. and H.sub.2O (169 L) was added to the reaction vessel. The biphasic mixture was then warmed to 20-30° C. and stirred for 10 min. After phase separation, the aqueous layer was collected and the organics were washed twice with H.sub.2O (169 L). The combined aqueous phases were then back-extracted with 10V of EtOAc (562 L). Next, the organic phases were combined and solvent exchanged into isopropanol by vacuum distillation. The concentrate was diluted to 843 L (15V) of isopropanol. The suspension was then heated to 75-85° C. and held until the solids dissolved. Then, (15V) of H.sub.2O (843 L) was added to the solution while maintaining a temperature of 70-80° C. At the end of the addition, the solution was cooled to 10-20° C. over 2 hrs. After stirring at 10-20° C. for an additional 2 hrs, the suspension was filtered. The vessel and wet cake were rinsed with (5V) of H.sub.2O (281 L), followed by 281 L of n-heptane. The white solids were then dried at 50° C. to yield 74.9 kg (96%) of 8-2. .sup.1H NMR (400 MHz, DMSO) (rotamers present) δ 8.33 (d, J=30.9 Hz, 1H), 7.54 (d, J=7.7 Hz, 1H), 7.41-7.20 (m, 15H), 5.77-5.55 (m, 1H), 5.20-4.87 (m, 8H), 4.42-4.04 (m, 2H), 3.77-3.42 (m, 2H), 3.40-3.34 (m, 1H), 2.95 (dd, J=12.0, 8.4 Hz, 1H), 2.49-2.36 (m, 1H), 2.38-2.11 (m, 1H), 1.73-1.43 (m, 1H), 1.15 (dd, J=16.8, 6.9 Hz, 3H). .sup.13C NMR (rotamers present) (126 MHz, DMSO) δ 170.91, 170.84, 170.69, 170.65, 156.53, 156.46, 156.02, 137.53, 137.51, 137.05, 136.98, 136.09, 135.95, 135.80, 128.84, 128.79, 128.69, 128.63, 128.59, 128.41, 128.32, 128.30, 128.23, 128.13, 128.11, 117.71, 117.35, 67.08, 66.91, 66.62, 66.29, 66.20, 65.82, 65.77, 65.16, 55.29, 55.18, 48.94, 48.88, 48.19, 48.03, 45.35, 43.15, 33.14, 32.91, 17.68, 17.04. HRMS (ESI.sup.+): [M+H].sup.+ calc. m/z=600.2704, found m/z=600.2707.

[0674] Step 3: Benzyl (3R,4S)-1-(((benzyloxy)carbonyl)-L-alanyl)-3-(((benzyloxy)carbonyl)amino)-4-(3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)propyl)pyrrolidine-3-carboxylate (8-3). To a N.sub.2 inerted reaction vessel containing anhydrous THF (60.0 L) at 0-10° C. was added [IrCl(cod)].sub.2 (211 g, 0.314 mol). The mixture was stirred to dissolve all solids and then 1,2-bis(diphenylphosphanyl)ethane (DPPE) (249 g, 0.625 mol) was added to the catalyst solution. After stirring for 1h, pinacol borane (4.77 L, 32.9 mol) was added, followed by stirring for an additional 10 min. Then, the catalyst solution was warmed to ambient temp and added to a glass lined 500 L vessel containing a suspension of benzyl (3R,4S)-4-allyl-1-(((benzyloxy)carbonyl)-L-alanyl)-3-(((benzyloxy)carbonyl)amino)pyrrolidine-3-carboxylate (8-2) (75.3 kg, 126 mol), pinacol borane (18.9 L, 131 mol) and anhydrous THF (240 L). After stirring for 4 hrs, the reaction was deemed complete by HPLC and the reaction solution was cooled to 0-10° C. Next, 15% aq. N-acetyl cysteine (NAC) (376 L) was added. The biphasic mixture was heated to 45-55° C. and stirred for 30 min. Then, after cooling to 15-25° C., MTBE (376 L) and aq. 13% sodium carbonate (376 L) were added sequentially. The biphasic mixture was allowed to stir for 15 min, followed by phase separation and removal of the aqueous layer. Then, 15% NAC (376 L) was added to the organic layer and the mixture was heated to 45-55° C. After stirring for 30 min, the mixture was cooled to 15-25° C. and 13% aq. sodium carbonate (376 L) was added. The biphasic mixture was then allowed to stir for 15 min, followed by phase separation. Next, the organic phase was washed with a brine solution and the organic phase was charged to a reaction vessel containing C-941 charcoal (7.53 kg). Stirring began and the suspension was heated to 45-55° C. After 2 hrs, the suspension was cooled to 15-20° C. and filtered. The organic filtrate was then concentrated and solvent swapped with 329 L of THF. Next, n-heptane (602 L) was slowly added and the subsequent suspension was stirred for 10 hrs. Next, additional n-heptane (151 L) was added to the crystallization vessel. After stirring for an additional 3 hrs at room temperature, the white suspension was filtered, rinsed, and dried to yield 8-3 as a white solid (82.9 kg, 92.4%). .sup.1H NMR (500 MHz, DMSO) (rotamers present) δ 8.23 (d, J=39.7 Hz, 1H), 7.52 (dd, J=14.8, 7.6 Hz, 1H), 7.41-7.12 (m, 15H), 5.24-4.80 (m, 6H), 4.42-4.02 (m, 2H), 3.89-3.66 (m, 1H), 3.67-3.55 (m, 1H), 3.38 (d, J=12.8 Hz, 1H), 2.94 (dd, J=11.8, 8.5 Hz, 1H), 2.46-2.25 (m, 1H), 1.56-0.97 (m, 17H), 0.97-0.76 (m, 1H), 0.71-0.40 (m, 2H). .sup.13C NMR (126 MHz, DMSO) (rotamers present) δ 170.92, 170.80, 156.53, 156.03, 137.51, 137.02, 136.07, 135.89, 128.82, 128.78, 128.63, 128.50, 128.43, 128.38, 128.36, 128.26, 128.22, 128.17, 128.12, 83.09, 67.48, 67.05, 66.97, 66.78, 66.22, 66.11, 65.80, 65.77, 65.48, 55.38, 55.26, 49.22, 47.99, 46.04, 43.74, 31.42, 31.30, 25.13, 25.09, 25.03, 24.99, 22.56, 22.47, 17.81, 17.02, 11.33. HRMS (ESI.sup.+): [M+H].sup.+ calc. m/z=728.3712, found m/z=728.3721.

[0675] Steps 4 and 5: (6aS,9aR)-9a-amino-8-((S)-2-aminopropanoyl)-3-ethoxyoctahydro-[1,2]oxaborocino[7,6-c]pyrrol-1(3H)-one (8-5). To a N.sub.2 inerted 500 gal vessel was charged benzyl (3R,4S)-1-(((benzyloxy)carbonyl)-L-alanyl)-3-(((benzyloxy)carbonyl)amino)-4-(3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)propyl)pyrrolidine-3-carboxylate (8-3) (82.9 kg, 113.9 mol) followed by THF (368.5 kg). The mixture was agitated at 20±5° C. until a solution formed. Next, 6.7% aqueous phosphoric acid (427.8 kg) followed by sodium periodate (29.3 kg) were added to the reactor and the mixture was agitated for NLT 8 hrs. Upon confirmation of the removal of the pinacol ester, water (415 L) and MTBE (306.7 kg) were added and the mixture was agitated for about 10 minutes. Agitation was stopped and upon settling, the lower level was removed from the reactor. Next the organic layer was washed twice with, THF (73.7 kg) and 5% ascorbic acid (422.0 kg). The organic layer was then washed with USP water until pH of the solution was above 5. Upon removal of the aqueous layer, the mixture was solvent exchanged into ethanol and transferred to an inerted hydrogenation vessel containing 83 L of water and 4.1 kg of 10% Pd/C. The mixture was then hydrogenated at 50 PSIG at 20±5° C. until less than 1% of starting material and intermediates remained by HPLC. Upon completion, the reactor was inerted and the catalyst removed by filtration. The reactor and solids were then rinsed with ethanol. To the inerted, rinsed reactor was charged 8.30 kg of C-941 charcoal and the filtered ethanol solution was recharged to the reaction vessel. The mixture agitated for NLT 30 min at 20±5° C. Next the mixture was filtered and the solids were washed with ethanol. All of the filtrates were combined and transferred to a clean reactor. Next, water was azeotropically removed through distillation with ethanol until KF of the mixture was below 1%, whereupon the product gradually precipitated in the reactor. The mixture was then heated to reflux and gradually cooled to −5±5° C. over 8 hrs. The mixture was then stirred at −5±5° C. for 12h and filtered. The isolated drug substance was then rinsed with cold line filtered ethanol and then dried at NMT 50° C. to yield 27 kg (80%) of 8-5. .sup.1H NMR (500 MHz, DMSO) (rotamers present) δ 7.20-6.57 (m, 2H), 3.87-3.76 (m, 1H), 3.72-3.58 (m, 1H), 3.57-3.18 (m, 4H), 3.18-2.76 (m, 1H), 2.47-2.22 (m, 1H), 1.90-1.62 (m, 3H), 1.50-1.36 (m, 1H), 1.14-1.04 (m, 6H), 1.05-0.90 (m, 1H), 0.74-0.61 (m, 1H), 0.50-0.35 (m, 1H). .sup.13C NMR (126 MHz, DMSO) (rotamers present) δ 174.49, 174.18, 172.81, 172.61, 66.52, 66.44, 65.24, 65.19, 57.03, 56.96, 51.90, 51.72, 49.28, 49.12, 49.08, 49.05, 48.02, 47.98, 47.58, 46.97, 40.50, 40.43, 40.34, 40.28, 40.17, 40.10, 40.00, 39.84, 39.67, 39.50, 27.40, 27.28, 27.04, 26.92, 23.47, 23.26, 23.23, 21.97, 21.38, 19.03, 18.66; MS (ESI.sup.+): [M-CH.sub.3CH.sub.2O].sup.+ calc. m/z=252.15, found m/z=252.11.

Example 5: Alternate Route to (6aS,9aR)-9a-amino-8-((S)-2-aminopropanoyl)-3-ethoxyoctahydro-[1,2]oxaborocino[7,6-c]pyrrol-1(3H)-one (8-4)

[0676] ##STR00257##

[0677] Step 1: To a 500 mL 3-neck round bottom flask equipped with a mechanic stirrer and J-KEM thermal controller was charged chloro-1,5-cyclooctadiene iridium (I) dimer (0.176 g, 0.262 mmol), 1,2-bis(diphenylphosphanyl)ethane (0.208 g, 0.523 mmol) and THF (78.5 mL, 5V). The bright orange/yellow solution was agitated for 10 min and 4,4,5,5-tetramethyl-1,3,2-dioxaborolane (4.35 g, 34.0 mmol) was charged (18.3-20.7° C.). The light green solution was agitated for 30 min and 8-2 (15.69 g, 26.2 mmol) was charged portion wise (3.92 g x 4) over 10 min maintaining 20±5° C. Following 1.5 h at rt the reaction was complete by HPLC (<2% SM).

[0678] Step 2: To the above solution was added a solution of 4.0N HCl in water (78.5 mL, 5V) maintaining 20±5° C. (the solution became cloudy after addition of 20 mL of HCl solution). The reaction mixture was stirred at rt for 1h, then NaIO.sub.4 solid was added (11.19 g, 52.3 mmol; exotherm, maintaining <30° C.). The reaction mixture was allowed to stir at rt for 3h, water (5V) and IPAc (10V) was added. The mixture was partitioned between IPAc and water. The aqueous layer was extracted with IPAc (10V). The combined organics were washed with 10% sodium thiosulfate aqueous solution (15V), dried over MgSO.sub.4, filtered and distilled in vacuum to ˜10.0 volumes. Activated charcoal (3.38 g, 20 wt %) was charged to the mixture and stirred at 45° C. (oil bath) for 1h. The mixture was filtered through a pad of celite with IPAc washing (3V) to give light yellow solution (total volumes: 13V). Crystallization was performed by slow addition of heptane (15V) at rt (solution became cloudy after addition of 30 mL Heptane). The mixture was stirred at rt for 30 minutes after addition of heptane. Filtration gave solid product (ML was used to transfer solid product to the filtration funnel). The resultant white solid was dried in a vacuum oven with N.sub.2 sweep at 40° C. overnight to afford the titled 8-4 (15.39 g, 91% yield, 94.7% pure @ 220 nm).

Example 6: Alternate Route A to (6aS,9aR)-9a-amino-8-((S)-2-aminopropanoyl)-3-ethoxyoctahydro-[1,2]oxaborocino[7,6-c]pyrrol-1(3H)-one (8-5)

[0679] ##STR00258##

[0680] Steps 1 and 2: Methyl (3R,4S)-4-(3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)propyl)-3-(2,2,2-trifluoroacetamido)pyrrolidine-3-carboxylate hydrochloride (10-7). To a 250 mL jacketed reactor with a jacket temp of 20° C. was charged chloro-1,5-cyclooctadiene iridium (I) dimer (0.141 g, 0.210 mmol), 1,2-bis(diphenylphosphanyl)ethane (0.184 g, 0.463 mmol) and dichloromethane (80 mL, 5V). The bright orange/yellow solution was agitated for 20 min and 4,4,5,5-tetramethyl-1,3,2-dioxaborolane (7.32 ml, 50.5 mmol) was charged maintaining the temperature. The pale yellow solution was agitated for 30 min and 10-1 (16 g, 42.1 mmol) was charged dropwise over 30 min as a solution in dichloromethane (80 mL, 5V) maintaining 20±5° C. Following 3 h at that temperature, the reaction was noted as complete by HPLC and was quenched by the addition of water (80 mL, 5V). The biphasic mixture was allowed to stir for 30 min. Agitation was ceased and the layers were separated. The organics layer was dried over sodium sulfate, filtered and distilled using house vacuum to ca. 2.0 volumes. Dioxane (64 mL, 4V) was charged to the mixture and distillation was continued to ˜2.0 volumes with a max jacket temperature of ˜55° C. The reaction mixture was cooled to 20° C. and 4N hydrochloric acid in dioxane (42.1 ml, 168 mmol) was charged with no exotherm observed. Following 15h at 23° C., the reaction was complete by HPLC and was diluted with MTBE (320 mL, 20V). Crystallization was initiated by addition of seed crystals (1 mg) and within 5 min a thick slurry was present. The reaction mixture was cooled to ˜10° C. over 15 min, agitated for 1h and filtered, rinsing with MTBE (2×50 mL). The resultant white solid was dried in a vacuum oven at 50° C. until constant weight to afford 10.7 (16.77 g, 90% yield, 95% purity). .sup.1H NMR (400 MHz, DMSO) δ 10.38 (s, 1H), 9.56 (s, 2H), 3.96 (d, J=12.8 Hz, 1H), 3.70 (s, 3H), 3.60-3.52 (m, 1H), 3.34 (d, J=12.8 Hz, 1H) 2.90 (t, J=10.9 Hz, 1H), 2.73-2.62 (m, 1H), 1.55-1.40 (m, 1H), 1.37-1.27 (m, 2H), 1.18 (s, 12H), 1.03-0.81 (m, 1H), 0.69 (t, J=7.7 Hz, 2H).

[0681] Steps 3: (3R,3′R,3″R,4S,4′S,4″S)-4,4′,4″-((1,3,5,2,4,6-trioxatriborinane-2,4,6-triyl)tris(propane-3,1-diyl))tris(1-(((benzyloxy)carbonyl)-L-alanyl)-3-(((benzyloxy)carbonyl)amino)pyrrolidine-3-carboxylic acid) (10-6). To a 500 mL jacketed reactor, triethylamine (20.06 ml, 144 mmol) was charged to a cold solution of 10-7 (16 g, 36.0 mmol) in 2-MeTHF (96 mL, 6 vol) maintaining a temperature of <5° C. The heterogeneous mixture was agitated for 20 min and Z-L-alanine (8.84 g, 39.6 mmol) was charged as a solid followed by dropwise addition of 1-propanephosphonic acid cyclic anhydride in 2-MeTHF (26.4 ml, 43.2 mmol) maintaining <5° C. (highly exothermic). Following 1h at 0° C., the reaction was noted as complete by HPLC, quenched by the addition of water (80 mL) and allowed to warm to rt. The layers were separated and the aqueous layer was extracted with 2-MeTHF (32 mL, 2 vol). The combined organic layers were washed with half saturated brine (64 mL). Next, lithium hydroxide monohydrate (6.04 g, 144 mmol) as a solution in water (160 mL) was charged to the organic layer (mild exotherm). The reaction mixture was warmed at 35° C. for 24h with vigorous agitation and whereupon the reaction was deemed complete by HPLC. The reaction mixture pH was then adjusted to ˜2 by the addition of concentrated HCl (12 mL) and diluted with MTBE (80 mL, 5 vol). Next, phenylboronic acid (4.39 g, 36.0 mmol) was charged as a solid. The reaction mixture was agitated for 16 h at 23° C. to complete the deprotection of the pinacol boronic ester and the layers were separated. The organic layer was extracted with 1N HCl (100 mL) and the combined aqueous layers were washed with additional MTBE (100 mL) containing phenylboronic acid (0.439 g, 3.6 mmol) to facilitate removal of pinacol from solution. The layers were separated and the aqueous layer containing product was adjusted to pH 9.0 by addition of 3N NaOH. Acetonitrile (80 mL) was added followed by benzyl (2,5-dioxopyrrolidin-1-yl) carbonate (9.86 g, 39.6 mmol) as a solid. The pH of the reaction was maintained between 8 and 10 by the addition of 1N NaOH. After 1h an additional charge of benzyl (2,5-dioxopyrrolidin-1-yl) carbonate (Z-OSu, 0.986 g, 3.96 mmol) was performed and the pH was continuously adjusted to maintain ˜8. The reaction was deemed complete by HPLC analysis after an additional 1h and the pH was adjusted to ˜3 facilitated by the addition of concentrated HCl. The reaction mixture was extracted with isopropyl acetate (3×300 mL) and the combined organic extracts were washed with brine (3×100 mL), dried over sodium sulfate and filtered to afford the crude monomer in isopropyl acetate. The reaction mixture was distilled under atmospheric pressure with a jacket temperature of 100° C. to a volume of 600 mL to remove water. Isopropyl acetate (100 mL) was charged and the distillation continued until a reaction volume of 600 mL was reached. During distillation the reaction mixture became thick with solids and was cooled to 0° C. over 1h. The mixture was then filtered, washed with isopropyl acetate (2×40 mL) and the wet solid was dried in a vacuum oven at 50° C. to afford 10-6 (13.52 g, 70% yield, 98.9% pure) as a white solid. .sup.1H NMR (500 MHz, DMSO) (rotamers present) δ 8.03 (d, J=35.8 Hz, 1H), 7.51 (dd, J=19.3, 7.7 Hz, 1H), 7.41-7.26 (m, 10H), 5.13-4.88 (m, 4H), 4.41-4.03 (m, 2H), 3.88-3.67 (m, 1H), 3.64-2.87 (m, 3H), 2.43-2.20 (m, 1H), 1.66-0.81 (m, 7H), 0.70-0.43 (m, 2H).

[0682] Step 4: (3R,3′R,3″R,4S,4′S,4″S)-4,4′,4″-((1,3,5,2,4,6-trioxatriborinane-2,4,6-triyl)tris(propane-3,1-diyl))tris(1-(((benzyloxy)carbonyl)-L-alanyl)-3-(((benzyloxy)carbonyl)amino)pyrrolidine-3-carboxylic acid) (10-6) was used to prepare 8-5 according the same procedure as in Step 5 of Example 4.

Example 7: Alternate Route B to (6aS,9aR)-9a-amino-8-((S)-2-aminopropanoyl)-3-ethoxyoctahydro-[1,2]oxaborocino[7,6-c]pyrrol-1(3H)-one (8-5)

[0683] ##STR00259##

[0684] Step 1: 1-(tert-Butyl) 3-methyl (3R,4S)-4-(3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)propyl)-3-(2,2,2-trifluoroacetamido)pyrrolidine-1,3-dicarboxylate (10-2) was prepare according to the same procedure as in Step 1 of Example 6.

[0685] Step 2: (3R,4S)-3-amino-4-(3-boronopropyl)pyrrolidine-3-carboxylic acid dihydrochloride (10-3). To a slurry of 10-2 (5 g, 9.84 mmol) in water (15 mL, 5V) was charged hydrochloric acid (8.13 mL, 98 mmol, 10 eq) and the resultant slurry was agitated at 75-80° C. while distilling low boiling organics. Upon reaction completion (8h), the mixture was azeotroped with dioxane (100 mL) to remove excess water and HCl maintaining to ˜3V. Acetonitrile (15 mL, 3v) was then charged and the mixture was agitated until filterable solids formed. The solids were collected by filtration, washed with dioxane, and dried in vacuo at 50° C. to afford 10-3 as a white solid (1.52 g, 54%). .sup.1H NMR (400 MHz, D.sub.2O) δ 3.95 (dd, J=12.8, 2.5 Hz, 1H), 3.78 (dd, J=11.8, 8.4 Hz, 1H), 3.55-3.47 (m, 1H), 3.29 (t, J=11.7 Hz, 1H), 2.61 (tdd, J=11.5, 8.3, 3.7 Hz, 1H), 1.66 (dddd, J=13.2, 10.2, 6.0, 3.6 Hz, 1H), 1.48-1.18 (m, 3H), 0.83-0.62 (m, 2H).

[0686] Step 3 and 4: (3R,3′R,3″R,4S,4′S,4″S)-4,4′,4″-((1,3,5,2,4,6-trioxatriborinane-2,4,6-triyl)tris(propane-3,1-diyl))tris(1-(((benzyloxy)carbonyl)-L-alanyl)-3-(((benzyloxy)carbonyl)amino)pyrrolidine-3-carboxylic acid) (10-6). A solution of 10-3 (13 g, 60 mmol, 1 eq) in water (15V, 195 mL) was adjusted to pH 9-10 with sodium hydroxide (50%, aq) at 0° C. To the solution was added 2,5-dioxopyrrolidin-1-yl ((benzyloxy)carbonyl)-L-alaninate (38.8 g, 120 mmol, 2 eq) and agitated at 0° C. (˜3h) until complete by HPLC (CAD). The reaction mixture was acidified to pH 3-3.5 by addition of hydrochloric acid (conc., aq) and then washed with toluene (5V) and ethyl acetate (2×5V). The aqueous layer was adjusted to pH 10-11 by the addition of sodium hydroxide (25%) and a solution of benzyl (2,5-dioxopyrrolidin-1-yl) carbonate (21.13 g, 85 mmol) in acetonitrile (5V, 60 mL) was added. The pH was maintained at 10-11 by continuous addition of sodium hydroxide (25%) at rt until the reaction was complete by HPLC (˜2h). The reaction mixture was acidified to pH 3-4 by addition of hydrochloric acid (conc., aq) and extracted with EtOAc (10V). The organics were washed with brine (3×1V) and distilled (atm.) at a constant volume while charging ethyl acetate (20V) until a thick while precipitate was present. The slurry was cooled to rt, agitated for 16h and filtered, washing with ethyl acetate (2V). The solids were then dried to afford 10-6 as a white solid (20.78 g, 64% yield). .sup.1H NMR (500 MHz, DMSO) (rotamers present) δ 8.03 (d, J=35.8 Hz, 1H), 7.51 (dd, J=19.3, 7.7 Hz, 1H), 7.41-7.26 (m, 10H), 5.13-4.88 (m, 4H), 4.41-4.03 (m, 2H), 3.88-3.67 (m, 1H), 3.64-2.87 (m, 3H), 2.43-2.20 (m, 1H), 1.66-0.81 (m, 7H), 0.70-0.43 (m, 2H).

[0687] Step 5: (3R,3′R,3″R,4S,4′S,4″S)-4,4′,4″-((1,3,5,2,4,6-trioxatriborinane-2,4,6-triyl)tris(propane-3,1-diyl))tris(1-(((benzyloxy)carbonyl)-L-alanyl)-3-(((benzyloxy)carbonyl)amino)pyrrolidine-3-carboxylic acid) (10-6) was used to prepare 8-5 according the same procedure as in Step 5 of Example 4.

[0688] All publications, patents, patent applications and other documents cited in this application are hereby incorporated by reference in their entireties for all purposes to the same extent as if each individual publication, patent, patent application or other document were individually indicated to be incorporated by reference for all purposes.

[0689] While various specific embodiments have been illustrated and described, it will be appreciated that various changes can be made without departing from the spirit and scope of the following claimed invention(s).