W. Hu et al. / Tetrahedron: Asymmetry 9 (1998) 4183–4192
4191
Hz, 2H), 7.47 (dd, JP–H=5.9 Hz, JH–H=7.9 Hz, 2H); 31P NMR (160 MHz, CDCl3) δ: −43.2 ppm; 13C
NMR (100 MHz, CDCl3) δ: 22.5, 53.1, 53.2, 53.3, 79.9 (d, JP–C=16.6 Hz), 80.8 (d, JP–C=16.6 Hz), 100.8,
100.9, 107.9 (d, JP–C=14.1 Hz), 108.2 (d, JP–C=10.0 Hz), 144.9 (d, JP–C=12.2 Hz), 145.2 (d, JP–C=13.7
Hz), 163.6 (d, JP–C=7.7 Hz), 163.7 (d, JP–C=4.9 Hz), 163.8; IR (KBr): 2980, 2954, 2868, 1591, 1479,
1446, 1413, 1374, 1328, 1275, 1223, 1196, 1012, 801 cm−1; MS: m/z 743 (M++1).
3.6. (−)-(4R,5R)-4,5-Bis[di-30-(20,60-dimethoxypyridyl)phosphinomethyl]-2,2-dimethyl-1,3-dioxolane-
cyclooctadiene-rhodium(I) tetrafluoroborate 11
Samples of 3 (74 mg, 0.10 mmol) and [Rh(COD)2]BF4 (46 mg, 0.10 mmol) were dissolved in THF (1
mL). The resulting solution was allowed to stand at ambient temperature for 12 h. The orange crystals
thus formed were filtered and washed with THF to afford 10 as brown crystals (86 mg, 83% theoretical
yield). Mp: 215–220°C (decomp.); [α]D −142.3 (c 1.2, CH2Cl2); 1H NMR (400 MHz, CDCl3) δ: 1.20
20
(s, 6H), 2.01 (m, 2H), 2.17 (m, 2H), 2.25–2.45 (m, 4H), 2.52 (m, 2H), 2.94 (m, 2H), 3.16 (m, 2H), 3.86
(s, 6H), 3.93 (m, 2H), 3.97 (s, 6H), 4.09 (s, 6H), 4.13 (s, 6H), 4.21 (m, 2H), 6.27 (d, J=8.2 Hz, 2H),
6.84 (d, J=8.1 Hz, 2H), 6.95 (dd, JP–H=8.5 Hz, JH–H=8.2 Hz, 2H), 9.26 (dd, JP–H=13.1 Hz, JH–H=8.1
Hz, 2H). 31P NMR (160 MHz, CDCl3) δ: 4.8 (d, JRh–P=144.2 Hz) ppm; 13C NMR (100 MHz, CDCl3)
δ: 14.8, 23.3, 26.3, 27.9, 33.1, 54.8, 55.1, 55.2, 68.6, 98.2, 99.2, 99.4, 99.6, 101.4, 101.7, 101.9, 102.4,
103.7, 110, 143.2, 153.7, 162.9, 164.3, 166.1, 168.0; IR (KBr): 2990, 2954, 1600, 1565, 1460, 1375,
1312, 1087, 1004 cm−1; MS (FAB): m/z 1041(M++1), 1011 (M−OCH3), 953 (M−BF4).
3.7. General procedure for the hydrogenation reaction
In an inert atmosphere glovebox, a stainless steel reactor was charged with the substrate for hydro-
genation (0.1 mmol) and the catalyst 11 (1.0 mg, 0.001 mmol) followed by the addition of methanol (2
mL). The reactor was closed and was pressurized to the pre-determined pressure of H2 and the mixture
was stirred at a pre-set temperature. The conversion and enantiomeric excess of the hydrogenated product
were determined by GC or HPLC.
Acknowledgements
We thank The Hong Kong Polytechnic University and the Hong Kong Research Grant Council for
financial support of the study (Project # HKP 92/94P).
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