1, 1′ -bis(phosphino)ferrocene ligands for alkoxycarbonylation

Abstract

Compound of formula (I) ##STR00001##
where R.sup.2, R.sup.4 are each independently selected from (C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.12)-cycloalkyl, (C.sub.3-C.sub.12)-heterocycloalkyl, (C.sub.6-C.sub.20)-aryl; the R.sup.1, R.sup.3 radicals are each a (C.sub.3-C.sub.20)-heteroaryl radical; R.sup.1, R.sup.3 may each independently be substituted by one or more substituents selected from (C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.12)-cycloalkyl, (C.sub.3-C.sub.12)-heterocycloalkyl, O(C.sub.1-C.sub.12)-alkyl, O(C.sub.1-C.sub.12)-alkyl-(C.sub.6-C.sub.20)-aryl, O(C.sub.3-C.sub.12)-cycloalkyl, S(C.sub.1-C.sub.12)-alkyl, S(C.sub.3-C.sub.12)-cycloalkyl, COO(C.sub.1-C.sub.12)-alkyl, COO(C.sub.3-C.sub.12)-cycloalkyl, CONH(C.sub.1-C.sub.12)-alkyl, CONH(C.sub.3-C.sub.12)-cycloalkyl, CO(C.sub.1-C.sub.12)-alkyl, CO(C.sub.3-C.sub.12)-cycloalkyl, N[(C.sub.1-C.sub.12)-alkyl].sub.2, (C.sub.6-C.sub.20)-aryl, (C.sub.6-C.sub.20)-aryl-(C.sub.1-C.sub.12)-alkyl, (C.sub.6-C.sub.20)-aryl-O(C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.20)-heteroaryl, (C.sub.3-C.sub.20)-heteroaryl-(C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.20)-heteroaryl-O(C.sub.1-C.sub.12)-alkyl, COOH, OH, SO.sub.3H, NH.sub.2, halogen; R.sup.2, R.sup.4, if they are (C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.12)-cycloalkyl, (C.sub.3-C.sub.12)-heterocycloalkyl or (C.sub.6-C.sub.20)-aryl, may each independently be substituted by one or more substituents selected from (C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.12)-cycloalkyl, (C.sub.3-C.sub.12)-heterocycloalkyl, O(C.sub.1-C.sub.12)-alkyl, O(C.sub.1-C.sub.12)-alkyl-(C.sub.6-C.sub.20)-aryl, O(C.sub.3-C.sub.12)-cycloalkyl, S(C.sub.1-C.sub.12)-alkyl, S(C.sub.3-C.sub.12)-cycloalkyl, COO(C.sub.1-C.sub.12)-alkyl, COO(C.sub.3-C.sub.12)-cycloalkyl, CONH(C.sub.1-C.sub.12)-alkyl, CONH(C.sub.3-C.sub.12)-cycloalkyl, CO(C.sub.1-C.sub.12)-alkyl, CO(C.sub.3-C.sub.12)-cycloalkyl, N[(C.sub.1-C.sub.12)-alkyl].sub.2, (C.sub.6-C.sub.20)-aryl, (C.sub.6-C.sub.20)-aryl-(C.sub.1-C.sub.12)-alkyl, (C.sub.6-C.sub.20)-aryl-O(C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.20)-heteroaryl, (C.sub.3-C.sub.20)-heteroaryl-(C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.20)-heteroaryl-O(C.sub.1-C.sub.12)-alkyl, COOH, OH, SO.sub.3H, NH.sub.2, halogen. The invention also relates to Pd complexes of the compound according to the invention, and to the use thereof in an alkoxycarbonylation process.

Claims

1. A diastereomerically pure compound having formula (I) ##STR00010## where R.sup.2, R.sup.4 are each independently selected from (C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.12)-cycloalkyl, (C.sub.3-C.sub.12)-heterocycloalkyl, or (C.sub.6-C.sub.20)-aryl; the R.sup.1, R.sup.3 radicals are each a (C.sub.3-C.sub.20)-heteroaryl radical; R.sup.1 and R.sup.3 each independently may be substituted by one or more substituents selected from (C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.12)-cycloalkyl, (C.sub.3-C.sub.12)-heterocycloalkyl, O(C.sub.1-C.sub.12)-alkyl, O(C.sub.1-C.sub.12)-alkyl-(C.sub.6-C.sub.20)-aryl, O(C.sub.3-C.sub.12)-cycloalkyl, S(C.sub.1-C.sub.12)-alkyl, S(C.sub.3-C.sub.12)-cycloalkyl, COO(C.sub.1-C.sub.12)-alkyl, COO(C.sub.3-C.sub.12)-cycloalkyl, CONH(C.sub.1-C.sub.12)-alkyl, CONH(C.sub.3-C.sub.12)-cycloalkyl, CO(C.sub.1-C.sub.12)-alkyl, CO(C.sub.3-C.sub.12)-cycloalkyl, N[(C.sub.1-C.sub.12)-alkyl].sub.2, (C.sub.6-C.sub.20)-aryl, (C.sub.6-C.sub.20)-aryl-(C.sub.1-C.sub.12)-alkyl, (C.sub.6-C.sub.20)-aryl-O(C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.20)-heteroaryl, (C.sub.3-C.sub.20)-heteroaryl-(C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.20)-heteroaryl-O(C.sub.1-C.sub.12)-alkyl, COOH, OH, SO.sub.3H, NH.sub.2, or halogen; and R.sup.2, R.sup.4, if they are (C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.12)-cycloalkyl, (C.sub.3-C.sub.12)-heterocycloalkyl or (C.sub.6-C.sub.20)-aryl, may each independently be substituted by one or more substituents selected from (C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.12)-cycloalkyl, (C.sub.3-C.sub.12)-heterocycloalkyl, O(C.sub.1-C.sub.12)-alkyl, O(C.sub.1-C.sub.12)-alkyl-(C.sub.6-C.sub.20)-aryl, O(C.sub.3-C.sub.12)-cycloalkyl, S(C.sub.1-C.sub.12)-alkyl, S(C.sub.3-C.sub.12)-cycloalkyl, COO(C.sub.1-C.sub.12)-alkyl, COO(C.sub.3-C.sub.12)-cycloalkyl, CONH(C.sub.1-C.sub.12)-alkyl, CONH(C.sub.3-C.sub.12)-cycloalkyl, CO(C.sub.1-C.sub.12)-alkyl, CO(C.sub.3-C.sub.12)-cycloalkyl, N[(C.sub.1-C.sub.12)-alkyl].sub.2, (C.sub.6-C.sub.20)-aryl, (C.sub.6-C.sub.20)-aryl-(C.sub.1-C.sub.12)-alkyl, (C.sub.6-C.sub.20)-aryl-O(C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.20)-heteroaryl, (C.sub.3-C.sub.20-heteroaryl-(C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.20)-heteroaryl-O(C.sub.1-C.sub.12)-alkyl, COOH, OH, SO.sub.3H, NH.sub.2, or halogen.

2. The compound according to claim 1, where R.sup.2, R.sup.4 are each independently selected from (C.sub.1-C.sub.12)-alkyl, cyclohexyl or phenyl.

3. The compound according to claim 1, where the R.sup.1, R.sup.3 are each a heteroaryl radical having five to ten ring atoms.

4. The compound according to claim 1, where R.sup.1, R.sup.3 are each independently selected from furyl, thienyl, pyrrolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, imidazolyl, pyrazolyl, furazanyl, tetrazolyl, pyridyl, pyridazinyl, pyrimidyl, pyrazinyl, benzofuranyl, indolyl, isoindolyl, benzimidazoiyl, quinolyl, or isoquinolyl.

5. The compound according to claim 1, where R.sup.1 and R.sup.3 are each pyridyl.

6. The compound according to claim 1, where R.sup.1 and R.sup.3 are each identical radicals and R.sup.2 and R.sup.4 are each identical radicals.

7. The compound according to claim 1 having the formula: ##STR00011##

8. A complex comprising Pd and the compound according to claim 1.

9. A process comprising: a) initially charging an ethylenically unsaturated compound; b)adding a complex comprising the compound according to claim 1 and Pd; c) adding an alcohol; d) feeding in CO to form a reaction mixture; e) heating the reaction mixture, with conversion of the ethylenically unsaturated compound to an ester.

10. The process according to claim 9, wherein the ethylenically unsaturated compound comprises 2 to 30 carbon atoms and optionally one or more functional groups selected from carboxyl, thiocarboxyl, sulpho, sulphinyl, carboxylic anhydride, imide, carboxylic ester, sulphonic ester, carbamoyl, sulphamoyl, cyano, carbonyl, carbonothioyl, hydroxyl, sulphhydryl, amino, ether, thioether, aryl, heteroaryl or silyl groups and/or halogen substituents.

11. The process according to claim 9, wherein the ethylenically unsaturated compound is selected from ethene, propene, 1-butene, cis- and/or trans-2-butene, isobutane, 1,3-butadiene, 1-pentene, cis- and/or trans-2-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 2-methyl-2-butene, hexene, tetramethylethylene, heptene, 1-octene, 2-octene, di-n-butene, and mixtures thereof.

12. The process according to claim 9, wherein the ethylenically unsaturated compound comprises 6 to 22 carbon atoms.

13. The process according to claim 9, wherein the compound comprising Pd in process step b) is selected from palladium dichloride, palladium(II) acetylacetonate, palladium(II) acetate, dichloro(1,5-cyclooctadiene)palladium(II), bis(dibenzylideneacetone)palladium, bis(acetonitrile)dichloropalladium(II), or palladium(cinnamyl) dichloride.

14. Process according to claim 9, wherein the alcohol in process step c) is selected from the group consisting of methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 2-propanol, tert-butanol, 3-pentanol, cyclohexanol, phenol, and mixtures thereof.

15. A process for the catalysis of an aikoxycarbonylation reaction, comprising introducing a compound according to claim 1.

16. A process for the catalysis of an alkoxycarbonylation reaction, comprising introducing a complex according to claim 8.

17. The process comprising: a) initially charging an ethylenically unsaturated compound; b)adding the complex according to claim 8; c) adding an alcohol; d) feeding in CO; e) heating the reaction mixture, with conversion of the ethylenica unsaturated compound to an ester.

18. The process according to claim 17, wherein the ethylenically unsaturated compound comprises 2 to 30 carbon atoms and optionally one or more functional groups selected from carboxyl, thiocarboxyl, sulpho, sulphinyl, carboxylic anhydride, imide, carboxylic ester, sulphonic ester, carbamoyl, sulphamoyl, cyano, carbonyl, carbonothioyl, hydroxyl, sulphhydryl, amino, ether, thioether, aryl, heteroaryl or silyl groups and/or halogen substituents.

19. The process according to claim 17, wherein the ethylenically unsaturated compound is selected from ethene, propene, 1-butene, cis- and/or trans-2-butene, isobutane, 1,3-butadiene, 1-pentene, cis- and/or trans-2-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 2-methyl-2-butene, hexene, tetramethylethylene, heptene, 1-octene, 2-octene, di-n-butene, and mixtures thereof.

20. The process according to claim 17, wherein the ethylenically unsaturated compound comprises 6 to 22 carbon atoms.

Description

EXAMPLES

(1) The examples which follow illustrate the invention.

(2) General Procedures

(3) All the preparations which follow were carried out under protective gas using standard Schlenk techniques. The solvents were dried over suitable desiccants before use (Purification of Laboratory Chemicals, W. L. F. Armarego (Author), Christina Chai (Author), Butterworth Heinemann (Elsevier), 6th edition, Oxford 2009).

(4) Phosphorus trichloride (Aldrich) was distilled under argon before use. All preparative operations were effected in baked-out vessels. The products were characterized by means of NMR spectroscopy. Chemical shifts () are reported in ppm. The .sup.31P NMR signals were referenced as follows: SR.sub.31P=SR.sub.1H*(BF.sub.31P/BF.sub.1H)=SR.sub.1H*0.4048. (Robin K. Harris, Edwin D. Becker, Sonia M. Cabral de Menezes, Robin Goodfellow, and Pierre Granger, Pure Appl. Chem., 2001, 73, 1795-1818; Robin K. Harris, Edwin D. Becker, Sonia M. Cabral de Menezes, Pierre Granger, Roy E. Hoffman and Kurt W. Zilm, Pure Appl. Chem., 2008, 80, 59-84).

(5) The recording of nuclear resonance spectra was effected on Bruker Avance 300 or Bruker Avance 400, gas chromatography analysis on Agilent GC 7890A, elemental analysis on Leco TruSpec CHNS and Varian ICP-OES 715, and ESI-TOF mass spectrometry on Thermo Electron Finnigan MAT 95-XP and Agilent 6890 N/5973 instruments.

Preparation of chloro-2-pyridyl-tert-butylphosphine (Precursor A)

(6) The Grignard for the synthesis of chloro-2-pyridyl-t-butylphosphine is prepared by the Knochel method with isopropylmagnesium chloride (Angew. Chem. 2004, 43, 2222-2226). The workup is effected according to the method of Budzelaar (Organometallics 1990, 9, 1222-1227).

(7) ##STR00005##

(8) 8.07 ml of a 1.3 M isopropylmagnesium chloride solution (Knochel's reagent) are introduced into a 50 ml round-bottom flask with magnetic stirrer and septum, and cooled to 15 C. Thereafter, 953.5 l (10 mmol) of 2-bromopyridine are rapidly added dropwise. The solution immediately turns yellow. It is allowed to warm up to 10 C. The conversion of the reaction is determined as follows: about 100 l solution are taken and introduced into 1 ml of a saturated ammonium chloride solution. If the solution bubbles, not much Grignard has formed yet. The aqueous solution is extracted with a pipette of ether and the organic phase is dried over Na.sub.2SO.sub.4. A GC of the ethereal solution is recorded. When a large amount of pyridine has formed compared to 2-bromopyridine, conversions are high. At 10 C., there has been little conversion. After warming up to room temperature and stirring for 1-2 hours, the reaction solution turns brown-yellow. A GC test shows complete conversion. Now the Grignard solution can be slowly added dropwise with a syringe pump to a solution of 1.748 g (11 mmol) of dichloro-tert-butylphosphine in 10 ml of THF which has been cooled to 15 C. beforehand. It is important that the dichloro-tert-butylphosphine solution is cooled. At room temperature, considerable amounts of dipyridyl-tert-butylphosphine would be obtained. A clear yellow solution is initially formed, which then turns cloudy. The mixture is left to warm up to room temperature and to stir overnight. According to GC-MS, a large amount of product has formed. The solvent is removed under high vacuum and a whitish solid which is brown in places is obtained. The solid is suspended with 20 ml of heptane and the solid is comminuted in an ultrasound bath. After allowing the white solid to settle out, the solution is decanted. The operation is repeated twice with 10-20 ml each time of heptane. After concentration of the heptane solution under high vacuum, it is distilled under reduced pressure. At 4.6 mbar, oil bath 120 C. and distillation temperature 98 C., the product can be distilled. 1.08 g of a colourless oil are obtained. (50%).

(9) Analytical data: .sup.1H NMR (300 MHz, C.sub.6D.sub.6): 8.36 (m, 1H, Py), 7.67 (m, 1H, Py), 7.03-6.93 (m, 1H, Py), 6.55-6.46 (m, 1H, Py), 1.07 (d, J=13.3 Hz, 9H, t-Bu).

(10) .sup.13C NMR (75 MHz, C.sub.6D.sub.6): 162.9, 162.6, 148.8, 135.5, 125.8, 125.7, 122.8, 35.3, 34.8, 25.9 and 25.8.

(11) .sup.31P NMR (121 MHz, C.sub.6D.sub.6) 97.9.

(12) MS (EI) m:z (relative intensity) 201 (M.sup.+, 2), 147(32), 145 (100), 109 (17), 78 (8), 57.1 (17).

Preparation of 1.1-bis(tert-butyl-2-pyridylphosphino)ferrocene (Compound 8)

(13) Chemicals used: 6.4 g of ferrocene (34.4 mmol) 11 ml of TMEDA (8 g, 68.9 mmol, 2 eq) 44.1 ml of 1.6N butyllithium (hexane) (70.6 mmol, 2.05 eq) 12.5 ml (13.7 g, 68 mmol) of chloro(tert-butyl-2-pyridyl)phosphine absolute heptane, absolute water, Na.sub.2SO.sub.4 (anhydrous)

(14) In a 250 ml three-neck flask provided with a low-temperature thermometer, a magnetic stirrer and reflux condenser, 6.4 g of ferrocene are weighed out under argon and 70 ml of absolute heptane are added. The ferrocene dissolves completely. Thereafter, 11 ml of TMEDA are added to the solution, followed by 44.1 ml of 1.6 N n-BuLi. The reaction solution is left to stand at room temperature overnight. A solid forms (large orange crystals). The supernatant solution is removed. 100 ml of heptane are added to the solids, the mixture is cooled to about 5 C. by means of an ice bath and then 12.5 ml of chloro(tert-butyl-2-pyridyl)phosphine dissolved in 10 ml of heptane are slowly added dropwise within half an hour. The large crystals dissolve gradually and a precipitate of lithium chloride is formed. This suspension is stirred at 5 C. for half an hour and then at room temperature for one hour. The organic phase is washed three times with 20 ml each time of degassed water. Subsequently, the organic phase is dried over Na.sub.2SO.sub.4 (anhydrous), the sodium sulphate is filtered off, the sodium sulphate is washed three times with 20 ml each time of heptane and the combined solution is dried under reduced pressure. An orange oil forms, which crystallizes fully in the refrigerator overnight. Yield: 17.1 g=96%.

(15) Analytical Data:

(16) .sup.1H NMR (300 MHz, C.sub.6D.sub.6): 8.66-8.56 (m, 2H, Py), 7.76-7.69 (m, 2H, Py), 7.08-6.97 (m, 2H, Py), 6.69-6.61 (m, 2H, Py), 5.17 (m, 1H, ferrocenyl), 4.94 (m, 1H, ferrocenyl), 4.37 (m, 1H, ferrocenyl), 4.17 (m, 1H, ferrocenyl), 4.05 (m, 1H, ferrocenyl), 3.98-3.93 (m, 3H, ferrocenyl), 1.14 (d, J=12.7 Hz, 9H, t-Bu), 1.12 (d, J=12.7 Hz, 9H, t-Bu).

(17) .sup.13C NMR (75 MHz, C.sub.6D.sub.6): 163.6, 163.5, 149.8, 149.8, 149.6, 134.6, 134.4, 132.5, 132.4, 132.0, 132.0, 122.7, 78.4, 78.0, 77.9, 77.6, 74.2, 74.1, 74.0, 74.0, 73.8, 72.6, 72.4, 71.7, 71.6, 71.5, 31.8, 31.7, 31.7, 31.6, 28.3 and 28.2.

(18) .sup.31P NMR (121 MHz, C.sub.6D.sub.6) 7.3 and 7.1

(19) Separation of the Diastereomer Forms of Compound 8

(20) As apparent from the two closely adjacent phosphine signals at 7.3 and 7.1 ppm, the compound 8 is in two diastereomer forms. These were separated from one another as follows.

(21) First the respective borane adducts of the diastereomer mixture were prepared, and then they were separated by column chromatography. It was possible to isolate three products: the respective diastereomeric borane adducts and a monosubstituted by-product.

(22) ##STR00006##

(23) A 50 ml round-bottom flask with nitrogen tap and magnetic stirrer bar is initially charged under argon with 700 mg (1.36 mmol) of the red-brown bis(2-pyridyl-tert-butylphosphino)ferrocene ligand and closed with a septum. After addition of 10 ml of THF, a clear orange-red solution has formed. At room temperature, 2.99 ml (2.2 eq, 2.99 mmol) of a 1 M borane solution are now added rapidly. After stirring for 2 days, there is still a clear orange-red solution. A thin-layer chromatogram clearly shows two products which can be stained with aqueous KMnO.sub.4 solution. R.sub.f1=0.15, R.sub.f2=0.31 (ethyl acetate:heptane=1:7). The borane adduct is chromatographed twice with a Combiflash apparatus (CombiFlash Rf, TELEDYNE ISCO, A Teledyne Technologies Company) (pure heptane for 5 min, then the ethyl acetate content is increased to 5% within 40 min). In the first run, it is possible to isolate the quickly eluting monosubstituted borane adduct. Yield: 28 mg (5.6%). In the second run, the diastereomer 1-BH.sub.3 is obtained in a 132 mg (17.9%) yield, and the somewhat more slowly eluting diastereomer 2-BH.sub.3 in a 376 mg (51%) yield. Both compounds are orange-brown solids.

(24) Monosubstituted by-product: .sup.1H NMR (300 MHz, CDCl.sub.3): 8.87 (m, 1H, py), 8.30 (m, 1H, py), 7.83 (m, 1H, py), 7.43 (m, 1H, py), 5.21 (m, 1H, ferrocenyl), 4.74 (m, 1H, ferrocenyl), 4.43 (m, 1H, ferrocenyl), 3.82 (s, 5H, Cp.sup.), 1.01 (d, J=14.5 Hz, 9H, tBu), 1.60-0.36 (br, BH.sub.3). .sup.13C NMR (75 MHz, CDCl.sub.3): 149.4, 149.3, 135.7, 135.5, 130.5, 130.2 (Py), 75.8, 75.6, 74.1, 71.9, 71.8, 70.6, 70.4 (ferrocenyl), 69.5 (Cp.sup.), 31.5, 31.1 and 25.9 (tBu).

(25) .sup.31P NMR (121 MHz, C.sub.dD.sub.6) 30.3 (m(br), PBH.sub.3), yield: yellow oil, 28 mg (5.6%).

(26) Diastereomer 1-BH.sub.3 (Cs): .sup.1H NMR (300 MHz, CDCl.sub.3): 8.91 (m, 2H, py), 8.26 (m, 2H, py), 7.83 (m, 2H, py), 7.44 (m, 2H, py), 5.25 (m, 2H, ferrocenyl), 4.24 (m, 2H, ferrocenyl), 4.07 (m, 2H, ferrocenyl), 3.62 (m, 2H, ferrocenyl), 0.99 (d, J=14.0 Hz, 18H, tBu), 1.54-0.19 (br, BH.sub.3, poorly resolved)).

(27) .sup.13C NMR (75 MHz, CDCl.sub.3): 154.7, 153.7, 149.7, 149.6, 135.6, 135.4, 130.3, 130.0, 124.8, 124.7 (Py), 76.1, 75.6, 75.9, 75.2, 74.7, 74.6, 72.9, 72.7, 66.3 and 65.5 (ferrocenyl), 31.4, 30.9, 25.8 and 25.7 (tBu)

(28) .sup.31P NMR (121 MHz, C.sub.6D.sub.6) 29.9 (d (br), J=68.1 Hz, PBH.sub.3), yield: 132 mg (17.9%), orange solid.

(29) Diastereomer 2-BH.sub.3 (C2): .sup.1H NMR (300 MHz, CDCl.sub.3): 8.88 (m, 2H, py), 8.28 (m, 2H, py), 7.85 (m, 2H, py), 7.47 (m, 2H, py), 4.73 (m, 2H, ferrocenyl), 4.67 (m, 2H, ferrocenyl), 4.29 (m, 2H, ferrocenyl), 3.57 (m, 2H, ferrocenyl), 0.98 (d, J=14.6 Hz, 18H, tBu), 1.61-0.25 (br, BH.sub.3, poorly resolved)).

(30) .sup.13C NMR (75 MHz, CDCl.sub.3): 154.8, 153.9, 149.3, 149.2, 135.7, 135.6, 130.5, 130.2, 124.8 (Py), 76.3, 74.8, 74.7, 74.6, 73.2, 73.1, 66.1 and 65.3 (ferrocenyl), 31.4, 31.0 and 25.8 (tBu).

(31) .sup.31P NMR (121 MHz, C.sub.8D.sub.6) 30.1 (d (br), J=63.7 Hz, PBH.sub.3). Yield: 376 mg (51%), orange solid.

(32) The free phosphine ligands (diastereomer 1 (Cs) 8.1 and the diastereomer 2 (C2) 8.2 according to the invention) can be prepared from the borane adducts by the following method:

(33) ##STR00007##

(34) In a 50 ml round bottom flask with magnetic stirrer bar which has been inertized by evacuating and filling within inert gas, 376 mg of diastereomer-2-BH.sub.3 (C2) are weighed out under argon and the flask is closed with a septum. Then 7 ml of absolute morpholine are added and an orange suspension forms, which gradually dissolves at 50 C. on a water bath to give a clear orange solution. According to the thin-layer chromatogram and .sup.31P NMR, the borane adduct has been fully converted to the free phosphine after 4 hours. After the now clear orange solution has cooled down, the morpholine is removed in an oil pump vacuum and the orange residue is chromatographed. The chromatography is necessary in order to separate the product from the morpholine-borane adduct. First of all, the eluent 2:1 (heptane/ethyl acetate) is freed of dissolved oxygen by passing argon gas through it for one hour. A 250 ml three-neck flask with septum, nitrogen connection and a column filled with silica gel 60 is sealed at the top with a further septum, inertized by repeated evacuation and filling with argon and eluted with the eluent. The orange residue is dissolved in 2-3 ml of eluent and applied to the column. The phosphine can now be chromatographed by applying eluent to the column under argon via a transfer needle. It is easy to see the end of the chromatography by the orange colour of the product. The chromatographed orange solution is transferred to a nitrogen flask with a syringe and freed of the solvent under high vacuum. A viscous yellow oil is obtained, which gradually solidifies. Yield 312 mg (87.3%)

(35) Diastereomer 2 (C2) 8.2,: .sup.1H NMR (300 MHz, C.sub.6D.sub.6): 8.58 (m, 2H, py), 7.72 (t,t, J=7.8 Hz, 1.3 Hz, 2H, py), 7.02 (t,t, J=7.6 Hz, J=2.1 Hz, 2H, py), 6.68-6.62 (m, 2H, py), 4.93 (m, 2H, ferrocenyl), 4.37 (m, 2H, ferrocenyl), 3.95 (m, 4H, ferrocenyl), 1.13 (d, J=12.0 Hz, 18H, tBu). .sup.13C NMR (75 MHz, CDCl.sub.3): 163.6 and 163.4 (C), 149.6, 149.5, 134.6, 134.4, 132.6, 131.9, 122.7 (py), 78.5, 77.9, 74.0, 73.9, 73.7, 72.5, 71.7, 71.5 (ferrocenyl), 31.8 31.6, 28.3 and 28.1 (tBu).

(36) .sup.31P NMR (121 MHz, C.sub.6D.sub.6) 7.1.

(37) HRMS (ESI) m/z.sup.+ calculated for C.sub.28H.sub.34FeN.sub.2P.sub.2(M+H).sup.+517.16197; found: 517.16221.

(38) In an analogous manner, it is also possible to prepare the other diastereomer-1 (Cs) 8.1. Here, 318 mg of the borane adduct were used and, after chromatography, 219 mg (73%) of the red-orange diastereomer-1 (Cs) 8.1 are obtained.

(39) Diastereomer 1 (Cs) 8.1: .sup.1H NMR (300 MHz, C.sub.6D.sub.6): 8.63 (m, 2H, py), 7.72 (t,t, J=7.8 Hz, 1.1 Hz, 2H, py), 7.04 (t,t, J=7.6 Hz, J=2.1 Hz, 2H, py), 6.66 (m, 2H, py), 5.17 (m, 2H, ferrocenyl), 4.17 (m, 2H, ferrocenyl), 4.05 (m, 2H, ferrocenyl), 3.95 (m, 2H, ferrocenyl), 1.11 (d, J=12.3 Hz, 18H, tBu).

(40) .sup.13C NMR (75 MHz, C.sub.6D.sub.6): 163.5 and 163.3 (C), 149.7, 149.6, 134.5, 134.3, 132.4, 131.8 and 122.6 (py), 77.9, 77.4, 74.1, 74.0, 73.8, 72.3, 71.5 and 71.4 (ferrocenyl), 31.7, 31.5, 28.2 and 28.0 (tBu).

(41) .sup.31P NMR (121 MHz, C.sub.6D.sub.6) 7.2.

(42) HRMS (ESI) m/z.sup.+calculated for C.sub.28H.sub.34FeN.sub.2P.sub.2(M+H).sup.+517.16197; found 517.16221.

(43) An isomer ratio 8.2:8.1 (C2:Cs) of 56:43 (NMR spectra) can be determined from the diastereomer mixture.

(44) Preparation of the Palladium Complexes K5.1 and K5.2

(45) ##STR00008##

(46) The corresponding palladium complexes K5.1a and K5.1b with Cs symmetry and the complex K5.2 according to the invention with C1 symmetry are prepared from the diastereomeric pure phosphine ligands 8.1 and 8.2 in the presence of maleimide in heptane as follows:

(47) Complex K5.2: 58.1 mg (0.274 mmol) of palladium precursor (cyclopentadienyl(allyl)palladium) are weighed out in a 10 ml Schlenk vessel and dissolved in 5 ml of freeze-thawed heptane. The red clear solution is filtered through Celite into a nitrogen-inertized 25 ml flask. In a second Schlenk vessel under argon, 150 mg (0.29 mmol) of diastereomer 8.2 (C2) and 30.4 mg (0.274 mmol) of N-methylmaleimide are dissolved in 6 ml of heptane. The N-methylmaleimide only goes completely into solution by heating at 60 C. on a water bath. The clear yellow-orange solution is slowly added dropwise at room temperature to the red palladium precursor solution with a syringe pump. The solution lightens in colour and a yellow precipitate forms. The next day, the precipitate is left to settle out and the supernatant solution is decanted. After washing three times with 1-2 ml of heptane, the yellow precipitate is dried by suction on an oil pump. 200 mg (95%) of a yellow solid are obtained. According to .sup.31P NMR a C1-symmetric complex must have formed from the C2-symmetric ligand, as shown by the characteristic two doublets.

(48) .sup.1H NMR (300 MHz, C.sub.6D.sub.6): 8.48 (m, 2H, py), 8.12 (m, 2H, py), 7.13 (m, 1 H, py), 7.02 (t,t, J=7.6 Hz, J=2.3 Hz, 1H, py), 6.63 (m, 2H, py), 5.32 (m, 1H, ferrocenyl), 4.89 (m, 1H, ferrocenyl), 4.45 (m, 2H, ferrocenyl), 3.95 (m, 1H, ferrocenyl), 3.92 (m, 2H, ferrocenyl), 3.85 (m; 2H, ferrocenyl), 3.44 (m; 1H, ferrocenyl), 3.03 (s, 3H, NMe), 1.36 (d, J=14.9 Hz, 9H, tBu), 1.32 (d, J=14.6 Hz, 9H, tBu).

(49) .sup.13C NMR (75 MHz, C.sub.6D.sub.6): 175.9 and 175.8 (CO), 160.2, 159.7, 158.5 and 158 (C), 149.5, 149.4, 135.6, 135.4, 135.1, 135.0, 134.8, 134.5, 133.9, 124.3, 123.9 (py), 78.6, 78.3, 76.8, 76.5, 75.0, 74.8, 74.4, 74.2, 73.8, 73.4, 72.7, 72.6, 72.5, 71.0, 70.5, 70.4 (ferrocenyl), 52.6, 52.5, 52.2, 52.1, 51.1, 51.0, 50.7, 50.6 (maleimide), 35.5 35.3, 35.1, 28.1, 28.0, 27.4, 27.3 (tBu), 23.5 (NMe).

(50) .sup.31P NMR (121 MHz, C.sub.6D.sub.6) 47.3 (d, J=16 Hz), 46.4 (d, J=16 Hz).

(51) Complex K5.1 (comparative example): The preparation of K5.1 from the diastereomer 8.1 is affected analogously to the preparation of K5.2.

(52) .sup.1H NMR (300 MHz, C.sub.6D.sub.6): 8.27 (m, 2.77H, py), 7.74 (t, J=7.3 Hz, 2H, py), 7.62 (m, 0.77 H, py), 6.81 (t,t, J=7.7 Hz, J=2.2 Hz, 2H, py), 6.66 (t,t, J=7.7 Hz, J=2.1 Hz, 0.77H, py), 6.39 (m, 2.77H, py), 4.66 (m, 0.77H, methine), 4.49 (m, 2H, methine), 4.42 (m, 0.77H, methine), 4.33 (m, 2H, methine), 4.27 (m; 2H, methine), 4.19 (m; 0.77H, methine), 4.05 (m; 2.77H, methine), 3.95 (m; 2.77H, methine), 3.10 (s, 3H, NMe), 3.03 (s, 1.21H, NMe), 1.36 (d, J=13.9 Hz, 25.26H, tBu).

(53) .sup.31P NMR (121 MHz, C.sub.6D.sub.6) 46.9 and 46.3. Yield: 46 mg, (90%), yellow sold.

(54) It is apparent from the .sup.1H NMR spectra that the ligand 8.1 (Cs) reacts to give two diastereomeric Cs-symmetric palladium complexes K5.1a and K5.1b (Cs) a ratio of 72:28, since the maleimide can assume two distinguishable positions. The ratio can be determined from the area integrals of the N-methyl groups at 3.10 and 3.03 ppm in the .sup.1H NMR. The .sup.31P NMR likewise shows two singlets, which can be assigned to the two possible diastereomeric complexes having Cs symmetry.

(55) The ligand diastereomer 8.2 (C2), by contrast, leads to a homogeneous complex with C1 symmetry. As a result of the firm binding of maleimide to the metal centre, the C2 symmetry is lost, but a rotation of the maleimide by 180, by contrast with the diastereomer 8.1 (Cs), would not lead to a new isomer. Here, the maleimide shows just one singlet at 3.03 ppm in the .sup.1H NMR and, owing to the C1 symmetry, 2 doublets in the .sup.31P NMR.

(56) General Method for Performance of the High-pressure Experiments

(57) General experimental method for autoclave experiments in glass vials:

(58) A 300 ml Parr reactor is used. Matched to this is an aluminium block of corresponding dimensions which has been manufactured in-house and which is suitable for heating by means of a conventional magnetic stirrer, for example from Heidolph. For the inside of the autoclave, a round metal plate of thickness about 1.5 cm was manufactured, containing 6 holes corresponding to the external diameter of the glass vials. Matching these glass vials, they are equipped with small magnetic stirrers. These glass vials are provided with screw caps and suitable septa and charged, using a special apparatus manufactured by glass blowers, under argon with the appropriate reactants, solvents and catalysts and additives. For this purpose, 6 vessels are filled at the same time; this enables the performance of 6 reactions at the same temperature and the same pressure in one experiment. Then these glass vessels are closed with screw caps and septa, and a small syringe cannula of suitable size is used to puncture each of the septa. This enables gas exchange later in the reaction. These vials are then placed in the metal plate and these are transferred into the autoclave under argon. The autoclave is purged with CO and filled at room temperature with the CO pressure intended. Then, by means of the magnetic stirrer, under magnetic stirring, the autoclave is heated to reaction temperature and the reaction is conducted for the appropriate period. Subsequently, the autoclave is cooled down to room temperature and the pressure is slowly released. Subsequently, the autoclave is purged with nitrogen. The vials are taken from the autoclave, and a defined amount of a suitable standard is added. A GC analysis is effected, the results of which are used to determine yields and selectivities.

(59) Analysis

(60) GC analysis: for the GC analysis, an Agilent 7890A gas chromatograph having a 30 m HP5 column is used. Temperature profile: 35 C., 10 min; 10 C./min to 200 C.; the injection volume is 1 l with a split of 50:1.

(61) Retention time for iso-C9 esters 19.502-20.439 min (main peak: 19.990 min)

(62) Retention time for n-C9 esters: 20.669, 20.730, 20.884, 21.266 min.

(63) Evaluation of the Experiments

(64) The n selectivities reported hereinafter relate to the proportion of terminal methoxycarbonylation based on the overall yield of methoxycarbonylation products.

(65) Methoxycarbonylation of 1-octene

(66) In order to examine the activity of the diastereomers K5.1 and K5.2 of the complex [Pd(Cp.sub.2Fe)(P(2-pyridyl)(t-butyl)).sub.2.sup.2-(N-methymaleinimide)], the diastereomerically pure crystals K5.2 are compared with a mixture of K5.1 and K5.2 in a molar ratio of 40:60 under identical conditions. In the case of the diastereomeric crystal form K5.2, there is a uniform compound present; in the case of the mixture, there are at least 3 diastereomeric compounds present: K5.1a, K5.1b, and K5.2.

(67) The benchmark reaction used is the methoxycarbonylation of 1-octene to methyl nonanoat.

(68) ##STR00009##

(69) In the experiments, the reaction conditions are chosen such that complete conversion cannot take place (40 bar CO, 60 C., T=variable). In order to conduct the experiments, 2 stock solutions are prepared. One stock solution consists of the respective complex (2.93 mg [Pd] in 5 ml MeOH); the other stock solution consists of the acid (22.8 mg para-toluenesulfonic acid in 10 mL MeOH). One millilitre in each case of stock solution are added to a 4 ml vial equipped with septum, cannula and a small magnetic stirrer bar under argon and the vial is placed into a carousel, which is placed in turn into a 300 ml Parr-autoclave. After purging with argon and CO, CO is injected to 40 bar and the autoclave is then inserted into an aluminium block preheated to 60 C. In the autoclave, therefore, there are two 4 ml vials, containing the respective complex in diastereomerically pure crystal form, and in the diastereomer mixture.

(70) Three experiments of this kind are conducted with variation in the reaction times of 15 minutes, 30 minutes and 40 minutes. After the reaction, the autoclave is brought to room temperature and cautiously decompressed. Then 300 L of isooctane are added to each vial as a standard for the quantitative GC determination and mixed well. The results are compiled in the following table:

(71) TABLE-US-00001 ester yield n selectivity reaction time catalyst (%) (%) (min) K5.2 30 84 15 mixture of K5.2 and 15 83 15 K5.1 (CE) K5.2 70 83 30 mixture K5.2 and 53 82 30 K5.1 (CE) K5.2 70 83 40 mixture K5.2 and 65 82 40 K5.1 (CE) (CE): Comparative Example

(72) It is apparent from table 3 that the diastereomerically pure crystals catalyse the methoxycarbonylation much more strongly than does the diastereomer mixture. After 15 minutes, the ester yield in the case of the diastereomerically pure catalyst is twice as high as in the case of the diastereomer mixture. Accordingly, the diastereomerically pure 1,1-bis(phosphino)ferrocene compounds according to the invention have very good catalytic properties for the alkoxycarbonylation of ethylenically unsaturated compounds, especially of long-chain olefins.