Synthesis and use of oxa-spirodiphosphine ligand

Abstract

The present invention relates to the technical field of chiral synthesis, and specifically provides a new type of oxa-spirodiphosphine ligands. The bisphosphine ligand is prepared with oxa-spirobisphenol as a starting material after triflation, palladium catalyzed coupling with diaryl phosphine oxide, reduction of trichlorosilane, further palladium catalyzed coupling with diaryl phosphine oxide, and further reduction of trichlorosilane. The oxa-spiro compound has central chirality, and thus includes L-oxa-spirodiphosphine ligand and R-oxa-spirodiphosphine ligand. The racemic spirodiphosphine ligand is capable of being synthesized from racemic oxa-spirobisphenol as a raw material. The present invention can be used as a chiral ligand in the asymmetric hydrogenation of unsaturated carboxylic acids. The complex of the ligand with ruthenium can achieve an enantioselectivity of greater than 99% in the asymmetric hydrogenation of methyl-cinnamic acid.

Claims

1. An oxa-spirodiphosphine ligand, having a structure of general Formula (I) below: ##STR00028## wherein in general Formula (I): R.sup.1 and R.sup.2 are hydrogen, in which R.sup.1, R.sup.2, R.sup.3 and R.sup.4 do not form a ring; R.sup.3 and R.sup.4 are hydrogen; R.sup.5 and R.sup.6 are hydrogen; and R.sup.7, R.sup.8 are aryl.

2. The compound according to claim 1, wherein the oxa-spirodiphosphine ligand is (±)-oxa-spirodiphosphine ligand, (+)-oxa-spirodiphosphine ligand, or (−)-oxa-spirodiphosphine ligand.

3. An oxa-spirodiphosphine ligand, wherein the oxa-spirodiphosphine ligand is a compound having a structure below: ##STR00029## in which Ar is aryl.

4. The compound according to claim 3, wherein Ar is phenyl.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic view showing the preparation of various chiral compounds according to the present invention, and the corresponding conversion rates and enantioselectivity ee.

DESCRIPTION OF THE EMBODIMENTS

(2) The present invention will be described below by way of examples with reference to accompanying drawings. However, the present invention is not limited thereto.

Example 1

Synthesis of (R)-2-H,2′-H-3,3′-spirobi[benzofuran]-4,4′-di(trifluoromethanesulfonate) 2

(3) ##STR00007##

(4) Under a N.sub.2 atmosphere, (S)-6 (7.68 g, 30 mmol) was added to a 250 mL reaction flask, and then dry dichloromethane (150 mL) was added. Pyridine (6.0 mL, 100 mmol) was added with stirring at room temperature. After the reaction system became clear, it was cooled to 0° C., and then Tf.sub.2O (12.0 mL, 70 mmol) was added dropwise. After that, the reaction system was warmed to room temperature and continuously stirred for 1 h. The reaction was quenched with water. The reaction system was washed with dilute hydrochloric acid, and the organic phase was removed of the solvent under reduced pressure, and then purified by column chromatography to obtain the product (S)-7 (15.6 g, yield: 99%)

(5) White solid. .sup.1H NMR (500 MHz, CDCl.sub.3) δ 4.70 (d, J=10.0 Hz, 2H, CH.sub.2), 4.87-4.90 (m, 2H, CH.sub.2), 6.91-6.93 (m, 4H, Ar), 7.32 (dd, J.sub.1=8.5 Hz, J.sub.2=8.0 Hz, 2H, Ar). .sup.13C {1H} NMR (126 MHz, CDCl.sub.3) δ 162.3, 145.8, 131.9, 119.8, 118.1 (q, J=320.0 Hz, CF.sub.3), 113.1, 110.4, 82.5, 54.9. .sup.19C {1H} NMR (126 MHz, CDCl.sub.3) δ −74.23. HRMS (ESI) calcd. for C.sub.171H.sub.1F.sub.6O.sub.8S.sub.2 [M+H].sup.+: 520.9800, Found: 520.9794, [α].sup.20.sub.D=+19.2 (c=0.5, acetone).

Example 2

Synthesis of (R)-4′-(diphenylphosphine oxide)-2H,2′H-3,3′-spirobi[benzofuran]-4-trifluoromethanesulfonate 3a

(6) ##STR00008##

(7) Under a N.sub.2 atmosphere, 2 (5.2 g, 10 mmol), dppb (213 mg, 0.05 mmol), Ph.sub.2POH (3.87 g, 15 mmol), Pd(OAc).sub.2 (112 mg, 0.05 mmol), and DIPEA (6.5 mL, 40 mmol) were added to a reaction flask, and finally DMSO (50 mL) containing no water and oxygen was added. The reaction was continued at 100° C. for 6 h. After cooling to room temperature, water was added to quench the reaction, and the reaction system was extracted with ethyl acetate. The organic phase was dried over anhydrous sodium sulfate, removed of the solvent under reduced pressure, and simply purified by column chromatography to obtain the product 3a (5.15 g, yield=90%).

(8) White solid. .sup.1H NMR (400 MHz, CDCl.sub.3) δ 4.64-4.68 (m, 2H, CH.sub.2), 4.77 (d, J=9.6 Hz, 1H, CH.sub.2), 5.15-5.18 (m, 1H, CH.sub.2), 6.40 (d, J=8.0 Hz, 1H, Ar), 6.58-6.60 (m, 1H, Ar), 6.78-6.80 (m, 1H, Ar), 6.88-6.90 (m, 1H, Ar), 6.94-6.98 (m, 2H, Ar), 7.05-7.13 (m, 3H, Ar), 7.16-7.20 (m, 2H, Ar), 7.24-7.28 (m, 4H, Ar). .sup.13C {1H} NMR (101 MHz, CDCl.sub.3) δ 162.6, 160.3, 145.4, 136.6, 134.5, 133.4 (m), 132.3, 132.0, 131.2, 130.0, 128.4 (m), 122.6 (m), 120.7, 112.3, 110.9, 109.4, 84.5, 82.9, 56.3, 26.9. .sup.31P {1H} NMR (202 MHz, CDCl.sub.3) δ 21.95 (s). HRMS (ESI) calcd. for C.sub.18H.sub.21O.sub.6F.sub.3PS [M+H].sup.+: 573.0749, Found: 573.0743, [α].sup.20.sub.D=+237.2 (c=0.5, acetone).

Example 3

Synthesis of (R)-4′-(diphenylphosphine)-2H,2′H-3,3′-spirobi[benzofuran]-4-trifluoromethanesulfonate 4a

(9) ##STR00009##

(10) In a 100 mL sealed tube, 3a (2.86 g, 5 mmol), DIPEA (6.6 mL, 40 mmol), 20 mL toluene, and trichlorosilane (2.0 mL, 20 mmol) were added. The reaction was stirred overnight at 120° C. The reaction system was quenched with excess saturated sodium bicarbonate solution, added with ethyl acetate (100 mL), and filtered through celite, and the organic phase was dried over anhydrous sodium sulfate. The organic phase was then removed of the solvent under reduced pressure, and then purified by column chromatography to obtain 4a as a white solid (2.5 g, yield=90%).

(11) White solid. .sup.1H NMR (400 MHz, CDCl.sub.3) δ 4.58-4.62 (m, 2H, CH.sub.2), 4.69-4.72 (m, 1H, CH.sub.2), 5.08-5.12 (m, 1H, CH.sub.2), 6.32-6.34 (m, 1H, Ar), 6.51-6.52 (m, 1H, Ar), 6.72-6.74 (m, 1H, Ar), 6.81-6.85 (m, 1H, Ar), 6.88-6.91 (m, 2H, Ar), 6.99-7.05 (m, 3H, Ar), 7.10-7.13 (m, 2H, Ar), 7.14-7.22 (m, 4H, Ar). .sup.13C {1H} NMR (126 MHz, CDCl.sub.3) δ 162.6, 160.3, 145.4, 136.6, 134.5 (m), 133.5 (m), 132.0, 131.3, 130.1, 128.8 (m), 127.8, 122.6, 112.3, 110.9, 109.5, 84.5, 83.0, 56.3. .sup.31P {1H} NMR (202 MHz, CDCl.sub.3) δ −22.32 (s). HRMS (ESI) calcd. for C.sub.18H.sub.21O.sub.5F.sub.3PS [M+H].sup.+: 557.0799, Found: 557.0794, [α].sup.20.sub.D=+56.0 (c=0.5, acetone).

Example 4

Synthesis of (R)-(4′-(diphenylphosphine)-2H,2′H-3,3′-spirobi[benzofuran]-4-diphenylphosphine oxide 5a

(12) ##STR00010##

(13) Under a N.sub.2 atmosphere, 4a (2.78 g, 5 mmol), dppb (107 mg, 0,025 mmol), Ph.sub.2POH (1.94 g, 7.5 mmol), Pd(OAc).sub.2 (56 mg, 0.0025 mmol), and DIPEA (3.2 mL, 20 mmol) were added to a reaction flask, and finally DMSO (20 mL) containing no water and oxygen was added. The reaction was continued at 100° C. for 6 h. After cooling to room temperature, water was added to quench the reaction, and the reaction system was extracted with ethyl acetate. The organic phase was dried over anhydrous sodium sulfate, removed of the solvent under reduced pressure, and simply purified by column chromatography to obtain the product 5a (2.66 g, yield=87%).

(14) White solid. .sup.1H NMR (500 MHz, CDCl.sub.3) δ 4.38 (d, J=9.5 Hz, 1H, CH.sub.2), 4.43 (d, J=9.0 Hz, 1H, CH.sub.2), 4.46 (d, J=9.5 Hz, 1H, CH.sub.2), 5.19 (d, J=9.0 Hz, 1H, CH.sub.2), 6.56-6.59 (m, 1H, Ar), 6.74-6.84 (m, 4H, Ar), 7.01-7.03 (m, 1H, Ar), 7.07-7.12 (m, 3H, Ar), 7.17-7.30 (m, 6H, Ar), 7.32-7.36 (m, 5H, Ar), 7.38-7.43 (m, 3H, Ar), 7.48-7.55 (m, 3H, Ar). .sup.13C {1H} NMR (126 MHz, CDCl.sub.3) δ 162.9, 160.4, 138.1, 137.9, 137.4, 134.9, 134.4 (m), 134.1 (m), 133.3 (m), 132.5, 132.1, 131.7 (m), 129.8, 128.9 (m), 128.4 (m), 128.1 (m), 126.7 (m), 113.4, 110.2, 85.2, 84.0, 58.2 (m). .sup.31P {1H} NMR (162 MHz, CDCl.sub.3) δ 29.41 (s), −20.96 (s). HRMS (ESI) calcd. for C.sub.39H.sub.31O.sub.3P.sub.2 [M+H].sup.+: 609.1748, Found: 609.1743, [α].sup.20.sub.D=+224.0 (c=0.5, acetone).

Example 5

Synthesis of (R)-4,4′-bis(diphenylphosphine)-2H,2′H-3,3′-spirobi[benzfuran] 6a

(15) ##STR00011##

(16) In a 100 mL sealed tube, 3a (1.216 g, 2 mmol), DIPEA (3.3 mL, 20 mmol), toluene (10 mL), and trichlorosilane (1.0 mL, 10 mmol) were added. The reaction was stirred overnight at 120° C. The reaction system was quenched with excess saturated sodium bicarbonate solution, added with ethyl acetate (100 mL), and filtered through celite, and the organic phase was dried over anhydrous sodium sulfate. The organic phase was then removed of the solvent under reduced pressure, and then purified by column chromatography to obtain 6a as a white solid (1.15 g, yield=96%).

(17) White solid. .sup.1H NMR (500 MHz, CDCl.sub.3) δ 4.38 (d, J=9.5 Hz, 2H, CH.sub.2), 4.49 (d, J=9.5 Hz, 2H, CH.sub.2), 6.67-6.68 (m, 2H, Ar), 6.85-6.86 (m, 2H, Ar), 6.92 (s, 4H, Ar), 7.01-7.03 (m, 1H, Ar), 7.11-7.23 (m, 12H, Ar), 7.29-7.30 (m, 6H, Ar). .sup.13C {1H} NMR (126 MHz, CDCl.sub.3) δ 160.8 (t, J=7.5 Hz), 137.1, 136.8, 135.0, 134.1, 133.4, 129.5, 128.7 128.4, 128.0, 127.3, 110.4, 83.6, 58.0 (m). .sup.31P {1H} NMR (162 MHz, CDCl.sub.3) δ −20.99 (s). HRMS (ESI) calcd. for C.sub.39H.sub.31O.sub.2P.sub.2 [M+H].sup.+: 593.1799, Found: 593.1782, [α].sup.20.sub.D=+246 (c=0.5, acetone).

Example 6

Synthesis of (R)-4′-(di-p-methylphenylphosphine oxide)-2H,2′H-3,3′-spirobi benzofuran-4-trifluoromethanesulfonate 3b

(18) ##STR00012##

(19) Under a N.sub.2 atmosphere, 2 (2.6 g, 5 mmol), dppb (107 mg, 0.025 mmol), Ar.sub.2POH (1.73 g, 7.5 mmol), Pd(OAc).sub.2 (56 mg, 0.025 mmol), and DIPEA (3.2 mL, 20 mmol) were added to a reaction flask, and finally DMSO (30 mL) containing no water and oxygen was added. The reaction was continued at 100° C. for 6 h. After cooling to room temperature, water was added to quench the reaction, and the reaction system was extracted with ethyl acetate. The organic phase was dried over anhydrous sodium sulfate, removed of the solvent under reduced pressure, and simply purified by column chromatography to obtain the product 3b (2.60 g, yield=87%).

(20) White solid. .sup.1H NMR (500 MHz, CDCl.sub.3) δ 2.36 (s, 3H, CH.sub.3), 2.38 (s, 3H, CH.sub.3), 4.60-4.62 (m, 1H, CH.sub.2), 4.70-4.74 (m, 2H, CH.sub.2), 5.69 (d, =8.5 Hz, 1H, CH.sub.2), 6.17 (d, J.sup.=8.0 Hz, 1H, Ar), 6.66-6.70 (m, 1H, Ar), 6.80-6.81 (m, 1H, Ar), 7.03-7.07 (m, 2H, Ar), 7.10-7.16 (m, 4H, Ar), 7.18-7.21 (m, 3H, Ar), 7.36-7.40 (m, 2H, Ar). .sup.13C {1H} NMR (126 MHz, CDCl.sub.3) δ 163.8, 161.9, 144.7, 142.0 (m), 131.9 (m), 131.5 (m), 131.2 (m), 130.7 (m), 130.2, 130.0, 129.3, 129.0 (m), 128.1, 126.9, 123.5, 121.8, 119.8, 116.6, 113.8, 111.7, 109.3, 85.6, 83.6, 56.5, 21.5. .sup.31P {1H} NMR (202 MHz, CDCl.sub.3) δ 29.86 (s). HRMS (ESI) calcd. for C.sub.30H.sub.25O.sub.6F.sub.3PS [M+H].sup.+: 601.1062, Found: 601.1056, [α].sup.20.sub.D=+108.4 (c=0.5, acetone).

Example 7

Synthesis of (R)-4′-(di-p-methylphenylphosphine)-2H,2′H-3,3′-spirobi[benzofuran]-4-trifluoromethanesulfonate 4b

(21) ##STR00013##

(22) In a 100 mL sealed tube, 3b (3.00 g, 5 mmol), DIPEA (3.2 mL, 20 mmol), toluene (20 mL), and trichlorosilane (2.0 mL, 20 mmol) were added. The reaction was stirred overnight at 120° C. The reaction system was quenched with excess saturated sodium bicarbonate solution, added with ethyl acetate (100 mL), and filtered through celite, and the organic phase was dried over anhydrous sodium sulfate. The organic phase was then removed of the solvent under reduced pressure, and then purified by column chromatography to obtain 4b as a white solid (2.70 g, yield=92%).

(23) White solid. .sup.1H NMR (400 MHz, CDCl.sub.3) δ 4.58-4.62 (m, 2H, CH.sub.2), 4.69-4.72 (m, 1H, CH.sub.2), 5.08-5.12 (m, 1H, CH.sub.2), 6.43 (d, J=9.0 Hz, 1H, Ar), 6.51-6.52 (m, 1H, Ar), 6.72-6.74 (m, 1H, Ar), 6.81-6.85 (m, 1H, Ar), 6.88-6.91 (m, 2H, Ar), 6.99-7.05 (m, 3H, Ar), 7.10-7.13 (m, 2H, Ar), 7.14-7.22 (m, 4H, Ar). .sup.13C {1H} NMR (101 MHz, CDCl.sub.3) δ 162.7, 160.2, 153.6, 145.5, 138.6, 133.7, 133.5, 131.1, 129.9, 129.3, 129.0, 127.6, 122.6, 112.3, 110.7, 109.4, 84.3, 82.9, 56.3, 26.9, 21.2. .sup.31P {1H} NMR (202 MHz, CDCl.sub.3) δ −22.32 (s). HRMS (ESI) calcd. for C.sub.30H.sub.25O.sub.5F.sub.3PS [M+H].sup.+: 585.1112, Found: 585.1107, [α].sup.20.sub.D=+111.4 (c=0.5, acetone).

Example 8

Synthesis of (R)-(4′-(di-p-methylphenylphosphine)-2H,2′H-3,3′-spirobi[benzofuran]-4-diphenylphosphine oxide 5b

(24) ##STR00014##

(25) Under a N.sub.2 atmosphere, 4b (0.584 g, 2 mmol), dppb (43 mg, 0.1 mmol), Ph.sub.2POH (0.69 g, 3 mmol), Pd(OAc).sub.2 (22.4 mg, 0.1 mmol), and DIPEA (0.50 mL, 4 mmol) were added to a reaction flask, and finally DMSO (20 mL) containing no water and oxygen was added. The reaction was continued at 100° C. for 6 h. After cooling to room temperature, water was added to quench the reaction, and the reaction system was extracted with ethyl acetate. The organic phase was dried over anhydrous sodium sulfate, removed of the solvent under reduced pressure, and simply purified by column chromatography to obtain the product 5b (1.12 g, yield=85%).

(26) White solid. .sup.1H NMR (500 MHz, CDCl.sub.3) δ 2.27 (s, 3H, CH.sub.3), 2.31 (s, 6H, CH.sub.3), 2.35 (s, 3H, CH.sub.3) 4.36 (d, J=9.0 Hz, 1H, CH.sub.2), 4.44 (t, J=9.5 Hz, 2H, CH.sub.2), 5.25 (d, J=9.0 Hz, 1H, CH.sub.2), 6.56-6.58 (m, 1H, Ar), 6.67-6.70 (m, 2H, Ar), 6.74-6.78 (m, 1H, Ar), 6.79-6.80 (m, 1H, Ar), 6.89-6.91 (m, 2H, Ar), 6.97-7.00 (m, 3H, Ar), 7.04-7.12 (m, 5H, Ar), 7.18-7.26 (m, 5H, Ar), 7.37-7.42 (m, 2H, Ar). .sup.13C {1H} NMR (126 MHz, CDCl.sub.3) δ 171.0, 162.8, 160.2, 141.7, 141.5, 138.5, 137.8, 137.6, 137.3, 134.0 (m), 133.2, 132.1, 131.7, 131.2, 130.0, 129.2 (m), 128.7 (m), 126.4, 113.0, 109.9, 85.0, 84.0, 60.3, 58.1 (m), 21.5, 21.2. .sup.31P {1H} NMR (202 MHz, CDCl.sub.3) δ 29.37 (s), −22.71 (s). HRMS (ESI) calcd. for C.sub.43H.sub.39O.sub.3P.sub.2 [M+H].sup.+: 665.2374, Found: 665.2369, [α].sup.20.sub.D=+211.2 (c=0.5, acetone).

Example 9

Synthesis of (R)-4,4′-bis(di-p-methylphenylphosphine)-2H,2′H-3,3′-spirobi[benzofuran]6b

(27) ##STR00015##

(28) In a 100 mL sealed tube, 5b (0.664 g, 1 mmol), DIPEA (3.3 mL, 20 mmol), toluene (10 mL), and trichlorosilane (1.0 mL, 10 mmol) were added. The reaction was stirred overnight at 120° C. The reaction system was quenched with excess saturated sodium bicarbonate solution, added with ethyl acetate (100 mL), and filtered through celite, and the organic phase was dried over anhydrous sodium sulfate. The organic phase was then removed of the solvent under reduced pressure, and then purified by column chromatography to obtain 6b as a white solid (0.62 g, yield=95%).

(29) White solid. .sup.1H NMR (500 MHz, CDCl.sub.3) δ 2.29 (s, 6H, CH.sub.3), 2.33 (s, 6H, CH.sub.3), 4.35 (d, J=9.5 Hz, 2H, CH.sub.2), 4.44 (d, J=9.0 Hz, 2H, CH.sub.2), 6.66-6.68 (m, 2H, Ar), 6.81-6.84 (m, 6H, Ar), 6.93-6.95 (m, 4H, Ar), 7.10 (s, 8H, Ar), 7.14-7.17 (m, 2H, Ar). .sup.13C {1H} NMR (126 MHz, CDCl.sub.3) δ 160.8 (m), 138.6, 137.7, 135.8, 134.8 (m), 134.2 (m), 133.5 (m), 129.2 (m), 128.8 (m), 110.1, 83.6 (m), 58.0 (m), 21.3. .sup.31P {1H} NMR (202 MHz, CDCl.sub.3) δ −22.82 (s). HRMS (ESI) calcd. for C.sub.43H.sub.39O.sub.2P.sub.2 [M+H].sup.+: 649.2425, Found: 649.2420, [α].sup.20.sub.D=+231.2 (c=0.5, acetone).

Example 10

Synthesis of (R)-4′-(di-p-methoxyphenylphosphine oxide)-2H,2′H-3,3′-spirobi[benzofuran]-4-trifluoromethanesulfonate 3c

(30) ##STR00016##

(31) Under a N.sub.2 atmosphere, 2 (5.2 g, 10 mmol), dppb (213 mg, 0.05 mmol), Ar.sub.2POH (3.93 g, 15 mmol), Pd(OAC).sub.2 (112 mg, 0.05 mmol), and DIPEA (6.5 mL, 40 mmol) were added to a reaction flask, and finally DMSO (50 mL) containing no water and oxygen was added. The reaction was continued at 100° C. for 6 h. After cooling to room temperature, water was added to quench the reaction, and the reaction system was extracted with ethyl acetate. The organic phase was dried over anhydrous sodium sulfate, removed of the solvent under reduced pressure, and simply purified by column chromatography to obtain the product 3c (5.78 g, yield=91%),

(32) White solid. .sup.1H NMR (500 MHz, CDCl.sub.3) δ 3.81 (s, 3H, CH.sub.3), 3.84 (s, 31, CH.sub.3), 4.62 (d, J=9.5 Hz, 1H, CH.sub.2), 4.70-4.75 (m, 2H, CH.sub.2), 5.71 (d, J=8.5 Hz, 1H, CH.sub.2), 6.23 (d, J=8.5 Hz, 1H, CH.sub.2), 6.65-6.70 (m, 1H, Ar), 6.80-6.82 (m, 3H, Ar), 6.88-6.91 (m, 2H, Ar), 7.03-7.07 (m, 2H, Ar), 7.16-7.27 (m, 3H, Ar), 7.39-7.43 (m, 2H, Ar). .sup.13C {1H} NMR (126 MHz, CDCl.sub.3) δ 163.8, 162.2 (m), 144.7, 133.7, 133.0, 131.4 (m), 130.3 (m), 129.3, 126.9, 125.9, 125.0, 122.8, 121.7 (m), 119.1, 116.6, 113.8 (m), 111.5, 109.2, 85.6, 83.6, 56.5, 55.2. .sup.31P {1H}NMR (202 MHz, CDCl.sub.3) δ 29.39 (s). HRMS (ESI) calcd. for C.sub.30H.sub.25O.sub.8F.sub.3PS [M+H].sup.+: 633.0960,

(33) Found: 633.0954, [α].sup.20.sub.D=+62.4 (c=0.5, acetone).

Example 11

Synthesis of (R)-4′-(di-p-methoxyphenylphosphine)-2H,2′H-3,3′-spirobi[benzofuran]-4-trifluoromethanesulfonate 4c

(34) ##STR00017##

(35) In a 100 mL sealed tube, 3c (2.86 g, 5 mmol), DIPEA (6.6 mL, 40 mmol), toluene (20 mL), and trichlorosilane (2.0 mL, 20 mmol) were added. The reaction was stirred overnight at 120° C. The reaction system was quenched with excess saturated sodium bicarbonate solution, added with ethyl acetate (100 mL), and filtered through celite, and the organic phase was dried over anhydrous sodium sulfate. The organic phase was then removed of the solvent under reduced pressure, and then purified by column chromatography to obtain 4c as a white solid (2.81 g, yield=91%).

(36) White solid. .sup.1H NMR (400 MHz, CDCl.sub.3) δ 4.58-4.62 (m, 2H, CH.sub.2), 4.69-4.72 (m, 1H, CH.sub.2), 5.08-5.12 (m, 1H, CH.sub.2), 6.43 (d, J=9.0 Hz, 1H, Ar), 6.51-6.52 (m, 1H, Ar), 6.72-6.74 (m, 1H, Ar), 6.81-6.85 (m, 1H, Ar), 6.88-6.91 (m, 2H, Ar), 6.99-7.05 (m, 3H, Ar), 7.10-7.13 (m, 2H, Ar), 7.14-7.22 (m, 4H, Ar). .sup.13C {1H} NMR (101 MHz, CDCl.sub.3) δ 162.7, 160.2, 153.6, 145.5, 138.6, 133.7, 133.5, 131.1, 129.9, 129.3, 129.0, 127.6, 122.6, 112.3, 110.7, 109.4, 84.3, 82.9, 56.3, 26.9, 21.2. .sup.31P {1H} NMR (202 MHz, CDCl.sub.3) δ −22.32 (s). HRMS (ESI) calcd. for C.sub.30H.sub.25O.sub.5F.sub.3PS [M+H].sup.+: 585.1112, Found: 585.1107, [α].sup.20.sub.D=+111.4 (c=0.5, acetone).

Example 12

Synthesis of (R)-(4′-(di-p-methoxyphenylphosphine)-2H,2′H-3,3′-spirobi[benzofuran]-4-diphenylphosphine oxide 5c

(37) ##STR00018##

(38) Under a N.sub.2 atmosphere, 4c (1,232 g, 2 mmol), dppb (43 mg, 0.1 mmol), Ph.sub.2POH (0.79 g, 3 mmol), Pd(OAc).sub.2 (22.4 mg, 0.1 mmol), and DIPEA (1.6 mL, 5 mmol) were added to a reaction flask, and finally DMSO (20 mL) containing no water and oxygen was added. The reaction was continued at 100° C. for 6 h. After cooling to room temperature, water was added to quench the reaction, and the reaction system was extracted with ethyl acetate. The organic phase was dried over anhydrous sodium sulfate, removed of the solvent under reduced pressure, and simply purified by column chromatography to obtain the product 5c (1.27 g, yield=87%).

(39) White solid. .sup.1H NMR (500 MHz, CDCl.sub.3) δ 3.73 (s, 3H, CH.sub.3), 3.74 (s, 3H, CH.sub.3), 3.77 (s, 6H, CH.sub.3), 3.80 (s, 3H, CH.sub.3) 4.37 (d, J=9.0 Hz, 1H, CH.sub.2), 4.45-4.47 (m, 2H, CH.sub.2), 5.28 (d, J=9.0 Hz, 1H, CH.sub.2), 6.55-6.57 (m, 1H, Ar), 6.64-6.71 (m, 61, Ar), 6.75-6.83 (m, 4H, Ar), 6.89-6.91 (m, 2H, Ar), 6.98-7.00 (m, 1H, Ar), 7.06-7.11 (m, 1H, Ar), 7.13-7.14 (m, 2H, Ar), 7.20-7.26 (m, 3H, Ar), 7.42-7.45 (m, 2H, Ar). .sup.13C {1H} NMR (126 MHz, CDCl.sub.3) δ 171.0, 162.8 (m), 161.9 (m), 160.3 (m), 137.5, 135.4, 134.8, 134.0 (m), 133.5, 130.6, 129.9, 128.5 (m), 128.1, 126.6 (m), 126.0 (m), 124.7, 123.8, 113.9 (m), 112.9, 109.8, 85.0, 84.2, 60.3, 58.1 (m), 55.0 (m). .sup.31P {1H} NMR (202 MHz, CDCl.sub.3) δ 28.75 (s), −24.27 (s). HRMS (ESI) calcd. for C.sub.43H.sub.39O.sub.7P.sub.2 [M+H].sup.+: 729.2171, Found: 729.2166, [α].sup.20.sub.D=+173.2 (c=0.5, acetone).

Example 13

Synthesis of (R)-4,4′-bis(di-p-methylphenylphosphine)-2H,2′H-3,3′-spirobi[benzofuran]6c

(40) ##STR00019##

(41) In a 100 mL sealed tube, 5c (0.728 g, 1 mmol), DIPEA (1.65 mL, 10 mmol), toluene (10 mL), and trichlorosilane (1.0 mL, 10 mmol) were added. The reaction was stirred overnight at 120° C. The reaction system was quenched with excess saturated sodium bicarbonate solution, added with ethyl acetate (100 mL), and filtered through celite, and the organic phase was dried over anhydrous sodium sulfate. The organic phase was then removed of the solvent under reduced pressure, and then purified by column chromatography to obtain 6c as a white solid (0.64 g, yield=90%).

(42) White solid. .sup.1H NMR (500 MHz, CDCl.sub.3) δ 3.75 (s, 6H, CH.sub.3), 3.79 (s, 6H, CH.sub.3), 4.36 (d, J=9.0 Hz, 2H, CH.sub.2), 4.46 (d, J=9.5 Hz, 2H, CH.sub.2), 6.64-6.70 (m, 6H, Ar), 6.82-6.85 (m, 10H, Ar), 7.12-7.18 (m, 6H, Ar). .sup.13C {1H} NMR (126 MHz, CDCl.sub.3) δ 160.8 (m), 160.1 (m), 136.2 (m), 135.5 (m), 134.5 (m), 129.3, 128.3 (m), 126.8, 114.0 (m), 110.0, 83.6 (m), 57.9 (m), 55.1 (m). .sup.31P {1H} NMR (202 MHz, CDCl.sub.3) δ −24.20 (s). HRMS (ESI) calcd. for C.sub.43H.sub.39O.sub.2P.sub.2 [M+H].sup.+: 649.2425, Found: 649.2420, [α].sup.20.sub.D=+133.6 (c=0.5, acetone).

Example 14

Synthesis of (R)-4′-bis(3,5-dimethylphenyl)phosphine oxide)-2H,2′H-3,3′-spirobi[benzofuran]-4-trifluoromethanesulfonate 3d

(43) ##STR00020##

(44) Under a N.sub.2 atmosphere, 2 (5.20 g, 10 mmol), dppb (213 mg, 0.05 mmol), Ar.sub.2POH (3.87 g, 15 mmol), Pd(OAc).sub.2 (112 mg, 0.05 mmol), and DIPEA (6.5 mL, 40 mmol) were added to a reaction flask, and finally DMSO (50 mL) containing no water and oxygen was added. The reaction was continued at 100° C. for 6 h. After cooling to room temperature, water was added to quench the reaction, and the reaction system was extracted with ethyl acetate. The organic phase was dried over anhydrous sodium sulfate, removed of the solvent under reduced pressure, and simply purified by column chromatography to obtain the product 3d (5.15 g, yield=82%).

(45) White solid. .sup.1H NMR (500 MHz, CDCl.sub.3) δ 2.15 (s, 6H, CH.sub.3), 2.17 (s, 6H, CH.sub.3), 4.54 (d, J=9.5 Hz, 1H, CH.sub.2), 4.62-4.64 (m, 2H, CH.sub.2), 5.69 (d, J=8.5 Hz, 1H, CH.sub.2), 6.07 (d, J=8.0 Hz, 1H, Ar), 6.63-6.67 (m, 1H, Ar), 6.72-6.78 (m, 3H, Ar), 6.93-6.98 (m, 2H, Ar), 7.00-7.05 (m, 4H, Ar), 7.12-7.18 (m, 1H, Ar). .sup.13C {1H} NMR (126 MHz, CDCl.sub.3) δ 163.9, 161.7, 144.7, 137.8 (m), 133.9, 133.3 (m), 131.5, 130.7, 130.0 (m), 129.4 (m), 128.7, 126.9, 121.6, 119.1, 116.5, 113.6, 111.3, 109.1, 85.7, 83.6, 56.3, 21.2. .sup.31P {1H} NMR (202 MHz, CDCl.sub.3) δ 29.59 (s). HRMS (ESI) calcd. for C.sub.32H.sub.29O.sub.6F.sub.3PS [M+H].sup.+: 629.1375, Found: 629.1369, [α].sup.20.sub.D=+196.4 (c=0.5, acetone).

Example 15

Synthesis of (R)-4′-(3,5-dimethylphenylphosphine)-2H,2′H-33′-spirobi[benzofuran]-4-trifluoromethanesulfonate 4d

(46) ##STR00021##

(47) In a 100 mL sealed tube, 3d (3.14 g, 5 mmol), DIPEA (6.6 mL, 40 mmol), (20 mL), and trichlorosilane (2.0 mL, 20 mmol) were added. The reaction was stirred overnight at 120° C. The reaction system was quenched with excess saturated sodium bicarbonate solution, added with ethyl acetate (100 mL), and filtered through celite, and the organic phase was dried over anhydrous sodium sulfate. The organic phase was then removed of the solvent under reduced pressure, and then purified by column chromatography to obtain 4d as a white solid (2.88 g, yield=94%).

(48) White solid. .sup.1H NMR (400 MHz, CDCl.sub.3) δ 2.16 (s, 6H, CH.sub.3), 2.19 (s, 6H, CH.sub.3), 4.44 (d, J=9.0 Hz, 1H, CH.sub.2), 4.63-4.67 (m, 2H, CH.sub.2), 5.15-5.18 (m, 1H, CH.sub.2), 6.36-6.40 (m, 1H, Ar), 6.51-6.53 (m, 3H, Ar), 6.65-6.68 (m, 1H, Ar), 6.73-6.79 (m, 3H, Ar), 6.83-6.87 (m, 3H, Ar), 6.99-7.01 (m, 1H, Ar), 7.11-7.15 (m, 1H, Ar). .sup.13C {1H} NMR (101 MHz, CDCl.sub.3) δ 162.6, 160.2, 145.3, 137.7 (m), 136.3, 135.2, 134.0, 131.8 (m), 130.5 (m), 129.9, 127.7, 122.8, 119.3, 116.7, 112.1, 110.6, 109.4, 84.4, 83.0, 56.2, 21.3. .sup.31P {1H} NMR (162 MHz, CDCl.sub.3) δ −21.56 (s). HRMS (ESI) calcd. for C.sub.32H.sub.29O.sub.5F.sub.3PS [M+H].sup.+: 613.1425, Found: 613.1420, [α].sup.20.sub.D=+60.0 (c=0.5, acetone).

Example 16

Synthesis of (R)-(4′-(3,5-dimethylphenyl phosphine)-2H,2′H-3,3′-spirobi[benzofuran]-4-diphenylphosphine oxide 5b

(49) ##STR00022##

(50) Under a N.sub.2 atmosphere, 4d (1.22 g, 2 mmol), dppb (107 mg, 0.1 mmol), Ph.sub.2POH (0.77 g, 3 mmol), Pd(OAc).sub.2 (22.4 mg, 0.1 mmol), and DIPEA (0.8 mL, 5 mmol) were added to a reaction flask, and finally DMSO (10 mL) containing no water and oxygen was added. The reaction was continued at 100° C. for 6 h. After cooling to room temperature, water was added to quench the reaction, and the reaction system was extracted with ethyl acetate. The organic phase was dried over anhydrous sodium sulfate, removed of the solvent under reduced pressure, and simply purified by column chromatography to obtain the product 5d (1.22 g, yield=86%).

(51) White solid. .sup.1H NMR (500 MHz, CDCl.sub.3) δ 2.04 (s, 6H, CH.sub.3), 2.06 (s, 6H, CH.sub.3), 2.24 (s, 6H, CH.sub.3), 2.29 (s, 6H, CH.sub.3), 4.14 (d, J=9.5 Hz, 1H, CH.sub.2), 4.41 (d, J=9.5 Hz, 2H, CH.sub.2), 5.15 (d, J=8.5 Hz, 1H, CH.sub.2), 6.49 (d, J=7.5 Hz, 1H, Ar), 6.70-6.73 (m, 1H, Ar), 6.75-6.78 (m, 2H, Ar), 6.86-6.90 (m, 3H, Ar), 6.95-6.98 (m, 3H, Ar), 7.03-7.06 (m, 2H, Ar), 7.07 (s, 1H, Ar), 7.09 (s, 1H, Ar), 7.19 (s, 1H, Ar), 7.21 (s, 1H, Ar), 7.24-7.25 (m, 1H, Ar). .sup.13C {1H} NMR (126 MHz, CDCl.sub.3) δ 162.8 (m), 159.8 (m), 137.7 (m), 136.8 (m), 135.0, 134.2, 134.0.133.2 (m), 132.8, 132.4 (m), 130.8 (m), 130.0 (m), 129.4 (m), 128.5 (m), 126.7, 126.4, 112.9, 109.9, 84.1, 83.3, 58.3 (m), 21.3 (m). .sup.31P {1H} NMR (202 MHz, CDCl.sub.3) δ −19.53 (s), 29.83 (s). HRMS (ESI) calcd. for C.sub.47H.sub.47O.sub.3P.sub.2 [M+H].sup.+: 721.3000, Found: 721.2995, [α].sup.20.sub.D=+137.2 (c=0.5, acetone).

Example 17

Synthesis of (R)-4,4′-bis(3,5-dimethylphenyl)phosphine-2H,2′H-3,3′-spirobi[benzofuran] 6d

(52) ##STR00023##

(53) In a 100 mL sealed tube, 5d (0.72 g, 1 mmol), DIPEA (3.3 mL, 20 mmol), toluene (10 mL), and trichlorosilane (1.0 mL, 10 mmol) were added. The reaction was stirred overnight at 120° C. The reaction system was quenched with excess saturated sodium bicarbonate solution, added with ethyl acetate (100 mL), and filtered through celite, and the organic phase was dried over anhydrous sodium sulfate. The organic phase was then removed of the solvent under reduced pressure, and then purified by column chromatography to obtain 6d as a white solid (0.65 g, yield=93%).

(54) White solid. .sup.1H NMR (500 MHz, CDCl.sub.3) δ 2.07 (s, 6H, CH.sub.3), 2.09 (s, 6H, CH.sub.3), 2.24 (s, 6H, CH.sub.3), 2.26 (s, 6H, CH.sub.3), 4.19-4.20 (m, 2H, CH.sub.2), 4.31-4.34 (m, 2H, CH.sub.2), 6.65-6.66 (m, 4H, Ar), 6.81-6.84 (m, 6H, Ar), 6.85-6.88 (m, 4H, Ar), 6.95-6.96 (m, 2H, Ar), 7.18-7.22 (m, 2H, Ar). .sup.13C {1H} NMR (126 MHz, CDCl.sub.3) δ 160.9 (m), 137.7 (m), 137.2 (m), 136.1, 133.8 (m), 132.3 (m), 131.0 (m), 129.6 (m), 127.1, 110.1, 82.9, 58.3 (m), 21.3 (m). .sup.31P {1H} NMR (202 MHz, CDCl.sub.3) δ −19.92 (s). HRMS (ESI) calcd. for C.sub.47H.sub.47O.sub.2P.sub.2 [M+H].sup.+: 705.3051, Found: 705.3046, [α].sup.20n=+138.0 (c=0.5, acetone).

Example 18

Synthesis of (R)-4′-(3,5-di-t-butylphenylphosphine oxide)-2H,2′H-3,3′-spirobi[benzofuran]-4-trifluoromethanesulfonate 3e

(55) ##STR00024##

(56) Under a N.sub.2 atmosphere, 2 (5.2 g, 10 mmol), dppb (213 mg, 0.05 mmol), Ar.sub.2POH (6.39 g, 15 mmol), Pd(OAC).sub.2 (112 mg, 0.05 mmol), and DIPEA (6.5 mL, 40 mmol) were added to a reaction flask, and finally DMSO (50 mL) containing no water and oxygen was added. The reaction was continued at 100° C. for 6 h. After cooling to room temperature, water was added to quench the reaction, and the reaction system was extracted with ethyl acetate. The organic phase was dried over anhydrous sodium sulfate, removed of the solvent under reduced pressure, and simply purified by column chromatography to obtain the product 3e (7.43 g, yield=93%).

(57) White solid. .sup.1H NMR (500 MHz, CDCl.sub.3) δ 1.18 (s, 9H, CH.sub.3), 1.19 (s, 9H, CH.sub.3), 1.20 (s, 9H, CH.sub.3), 1.21 (s, 9H, CH.sub.3), 4.54-4.56 (m, 1H, CH.sub.2), 4.62-4.64 (m, 1H, CH.sub.2), 4.80-4.82 (m, 2H, CH.sub.2), 6.63-6.68 (m, 2H, Ar), 6.82-6.88 (m, 6H, Ar), 6.90-6.94 (m, 2H, Ar), 7.15-7.21 (m, 1H, Ar), 7.26-7.34 (m, 1H, Ar). .sup.13C {1H} NMR (126 MHz, CDCl.sub.3) δ 162.9, 160.1, 150.5, 150.2, 145.7, 136.0 (m), 135.5, 134.4, 131.2, 129.6, 128.4, 127.5, 122.4 (m), 112.5, 110.5, 109.6, 83.5, 82.3, 56.4 (m), 34.8 (m), 31.3 (m). .sup.31P {1H} NMR (202 MHz, CDCl.sub.3) δ −19.74 (s). HRMS (ESI) calcd. for C.sub.44H.sub.53O.sub.6F.sub.3PS [M+H].sup.+: 797.3253, Found: 797.3247, [α].sup.20.sub.D=+109.6 (c=0.5, acetone).

Example 19

Synthesis of (R)-4′-(3,5-di-t-butylphenylphosphine)-2H,2′H-3,3′-spirobi[benzofuran]-4-trifluoromethanesulfonate 4e

(58) ##STR00025##

(59) In a 100 mL sealed tube, 3e (3.98 g, 5 mmol), DIPEA (6.6 mL, 40 mmol), (20 mL), and trichlorosilane (2.0 mL, 20 mmol) were added. The reaction was stirred overnight at 120° C. The reaction system was quenched with excess saturated sodium bicarbonate solution, added with ethyl acetate (100 mL), and filtered through celite, and the organic phase was dried over anhydrous sodium sulfate. The organic phase was then removed of the solvent under reduced pressure, and then purified by column chromatography to obtain 4e as a white solid (3.51 g, yield=90%).

(60) White solid. .sup.1H NMR (500 MHz, CDCl.sub.3) δ 1.17 (s, 9H, CH.sub.3), 1.19 (s, 9H, CH.sub.3), 1.20 (s, 9H, CH.sub.3), 1.21 (s, 9H, CH.sub.3), 4.52-4.55 (m, 1H, CH.sub.2), 4.60-4.63 (m, 1H, CH.sub.2), 4.77-4.82 (m, 2H, CH.sub.2), 6.61-6.69 (m, 2H, Ar), 6.80-6.94 (m, 6H, Ar), 7.14-7.22 (m, 2H, Ar), 7.28-7.34 (m, 2H, Ar). .sup.13C {1H} NMR (126 MHz, CDCl.sub.3) δ 162.9, 160.1 (m), 150.5 (m), 145.8, 136.1 (m), 135.5 (m), 134.4, 131.9 (m), 131.2, 129.6, 128.4 (m), 127.5, 122.4 (m), 116.9, 112.6, 110.6, 109.6, 83.5, 82.4, 56.4 (m), 34.8 (m), 31.3 (m). .sup.31P {1H} NMR (202 MHz, CDCl.sub.3) δ −19.73 (s). HRMS (ESI) calcd. for C.sub.32H.sub.29O.sub.5F.sub.3PS [M+H].sup.+: 781.3303, Found: 781.3298, [α].sup.20.sub.D=+78.8 (c=0.5, acetone).

Example 20

Synthesis of (R)-(4′-(3,5-di-t-butyl phenylphosphine)-2H,2′H-3,3′-spirobi[benzofuran]-4-di phenyl phosphine oxide 5e

(61) ##STR00026##

(62) Under a N.sub.2 atmosphere, 4e (1.56 g, 2 mmol), dppb (43 mg, 0.1 mmol), Ph.sub.2POH (1.28 g, 3 mmol), Pd(OAc).sub.2 (22.4 mg, 0.1 mmol), and DIPEA (1.6 mL, 10 mmol) were added to a reaction flask, and finally DMSO (10 mL) containing no water and oxygen was added. The reaction was continued at 100° C. for 6 h. After cooling to room temperature, water was added to quench the reaction, and the reaction system was extracted with ethyl acetate. The organic phase was dried over anhydrous sodium sulfate, removed of the solvent under reduced pressure, and simply purified by column chromatography to obtain the product 5e (1.85 g, yield=92%).

(63) White solid. .sup.1H NMR (500 MHz, CDCl.sub.3) δ 1.95 (s, 18H, CH.sub.3), 1.02 (s, 18H, CH.sub.3), 1.27 (s, 18H, CH.sub.3), 1.30 (s, 18H, CH.sub.3), 3.78 (d, J=8.8 Hz, 1H, CH.sub.2), 4.36 (d, J=9.6 Hz, 1H, CH.sub.2), 4.45 (d, J=8.4 Hz, 1H, CH.sub.2), 4.91 (d, J=8.4 Hz, 1H, CH.sub.2), 6.67 (d, J=6.8 Hz, 2H, Ar), 6.76-6.78 (m, 1H, Ar), 6.86-6.90 (m, 2H, Ar), 6.97-7.01 (m, 1H, Ar), 7.06-7.10 (m, 2H, Ar), 7.16-7.20 (m, 1H, Ar), 7.22-7.24 (m, 2H, Ar), 7.39 (s, 2H, Ar), 7.41 (s, 2H, Ar), 7.49 (s, 2H, Ar), 7.61 (d, J=8.0 Hz, 2H, Ar), 7.65 (d, J=9.6 Hz, 2H, Ar). .sup.13C {1H} NMR (126 MHz, CDCl.sub.3) δ 162.3, 159.0, 150.4 (m), 149.5 (m), 137.7, 137.3 (m), 135.5 (m), 134.7, 133.9 (m), 132.9, 132.4 (m), 129.6 (m), 128.0 (m), 127.5, 126.5 (m), 122.9, 120.7, 112.2, 109.9, 81.4, 81.3, 59.1, 34.8 (m), 31.2 (m). .sup.31P {1H} NMR (202 MHz, CDCl.sub.3) δ 30.86 (s), −16.07 (s). HRMS (ESI) calcd. for C.sub.71H.sub.95O.sub.3P.sub.2 [M+H].sup.+: 1057.6756, Found: 1057.6751, [α].sup.20.sub.D=+152.4 (c=0.5, acetone).

Example 21

Synthesis of (R)-4,4′-bis(3,5-di-butyl phenylphosphine)-2H,2′H-3,3′-spirobi[benzofuran] 6e

(64) ##STR00027##

(65) In a 100 mL sealed tube, 5e (1.01 g, 1 mmol), DIPEA (1.65 mL, 10 mmol), toluene (10 mL), and trichlorosilane (1.0 mL, 10 mmol) were added. The reaction was stirred overnight at 120° C. The reaction system was quenched with excess saturated sodium bicarbonate solution, added with ethyl acetate (100 mL), and filtered through celite, and the organic phase was dried over anhydrous sodium sulfate. The organic phase was then removed of the solvent under reduced pressure, and then purified by column chromatography to obtain 6e as a white solid (0.82 g, yield=79%).

(66) White solid. .sup.1H NMR (500 MHz, CDCl.sub.3) δ 0.99 (s, 36H, CH.sub.3), 1.25 (s, 36H, CH.sub.3), 3.85 (d, J=9.0 Hz, 2H, CH.sub.2), 4.25 (d, J=8.5 Hz, 2H, CH.sub.2), 6.80 (d, J=8.0 Hz, 2H, Ar), 6.91-6.93 (m, 2H, Ar), 7.01-7.02 (m, 4H, Ar), 7.09-7.10 (m, 2H, Ar), 7.15-7.18 (m, 2H, Ar), 7.25-7.36 (m, 4H, Ar), 7.37 (s, 2H, Ar). .sup.13C {1H} NMR (126 MHz, CDCl.sub.3) δ 160.5 (m), 150.4 (m), 149.2 (m), 139.0, 137.4, 135.5 (m), 131.4 (m), 129.6 (m), 126.9 (m), 123.0, 120.9, 110.0, 80.4, 59.1 (m), 34.8 (m), 31.4 (m). .sup.31P {1H} NMR (202 MHz, CDCl.sub.3) δ −15.41 (s). HRMS (ESI) calcd. for C.sub.71H.sub.95O.sub.2P.sub.2 [M+H].sup.+: 1041.6807, Found: 1041.6802, [α].sup.20.sub.D=+140.4 (c=0.5, acetone).

Example 22

(67) Preparation of the catalyst Ru(6a)OAc.sub.2:

(68) Under a N.sub.2 atmosphere, [RuPhCl.sub.2].sub.2 (25 mg, 0.05 mmol) and the ligand 6a (61 mg, 0.103 mmol) were added to a 10 mL one-neck flask, and then DMF (2 mL) were added. The reaction was continued at 100° C. for 3 h. After cooling to room temperature, 1.5 mL of a solution of anhydrous sodium acetate (0.111 g, 1.3 mmol) in methanol was added. After 20 min, deoxygenated deionized water was added. A gray solid was precipitated from the reaction system, and filtered out. The solvent and water were removed under reduced pressure to obtain the catalyst Ru(6a)OAc.sub.2 (57 mg, yield=71%).

Example 23

(69) Preparation of catalyst Ru(6a)(CF.sub.3CO).sub.2:

(70) Under a N.sub.2 atmosphere, bis(2-methylallyl)-cycloocta-1,5-diene ruthenium (32 mg, 0.05 mmol) and the ligand 6a (61 mg, 0.103 mmol) were added to a 10 mL one-neck flask, and then acetone (2 mL) were added. The reaction was continued at 40° C. for 0.5 h. Then, trifluoroacetic acid (33 mg, 0.3 mmol) was added and stirred overnight at 40° C. The solvent was removed under reduced pressure, and then petroleum ether (1 mL) was added, and filtered to obtain the target product Ru(6a)(CF.sub.3CO).sub.2 (81 mg, yield=88%).

Example 24

(71) Use of ligand 6a in the asymmetric hydrogenation of 2-methylcinnamic acid:

(72) Under a N.sub.2 atmosphere, 2-methylcinnamic acid (162 mg, 1 mmol), the catalyst Ru(6a)OAc.sub.2 (0.8 mg, 0.001 mmol) and methanol (1 mL) were added to a hydrogenation vial. After 12 h under a hydrogen atmosphere of 10 atm, the raw material was completely converted into a product. The product and aniline were condensed to form an amide to measure the enantioselectivity of the product (ee>99%). HPLC conditions: Daicel ADH, volume of injection: 2 μL (c=1 mg/mL), IPA/hexane=90/10, 1.0 mL/Min, 210 nm, t.sub.R (major)=26.8 Min, t.sub.R (minor)=29.7 Min.

(73) The conversion rate of various substances in the presence of 6a is shown in FIG. 1.

(74) The foregoing is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it should not be considered that the specific implementation of the present invention is limited thereto. Some simple deductions or replacements can be made by those ordinarily skilled in the art to which the present invention pertains without departing from the conception of the present invention, which are all regarded as falling within the protection scope of the present invention.