Reaction Steps
A solution of (±)-ethyl [3-(t-butyldimethylsilyloxy)cyclopentenyl]butylphosphinate (8) (3.20 g, 9.23 mmol) in ethanol (30 cm3) was hydrogenated over palladium on carbon (50 mg) at 40 psi for 3 hours. The catalyst was removed by filtration through celite, which was washed with methanol (3×30 cm3). The solvent was removed in vacuo to yield the desired title compound (9) in quantitative yield (>90% cis isomer (9) by NMR spectroscopy) as a colourless oil, which was used in the next step without further purification (2.55g, 79%) (data for cis isomer only is reported): 1H-NMR (300 MHz, CDCl3) δH 0.05 (6H, s, Si(CH3)2), 0.89 (9H, s, SiC(CH3)3), 0.90 and 0.92 (3H, 2×d, J=7.2 and 9.3 Hz, PCH2CH2CH2CH3), 1.23-2.21 (16H, m, C(1)—H, C(2)—H, C(2)—H′, C(4)—H, C(4)—H′, C(5)—H and C(5)—H′, POCH2CH3, PCH2CH2CH2CH3, PCH2CH2CH2CH3, PCH2CH2CH2CH3), 3.99-4.35 (3H, m, POCH2CH3, C(3)—H); 13C-NMR (75 MHz, CDCl3) δC −4.89 and −4.87 (d, 6JPC=1.43 Hz, Si(CH3)2), 13.51 (s, PCH2CH2CH2CH3), 16.63 and 16.70 (d, 6JPC=5.4 Hz, SiC(CH3)3), 17.98 (s, POCH2CH3), 23.60 and 23.77 (2×d, 3JPC=12.75 and 13.13 Hz, PCH2CH2CH2CH3), 23.91 (s, C(5)), 24.10 (s, PCH2CH2CH2CH3), 25.74 (s, SiC(CH3)3), 25.26 and 26.47 (2×d, JPC=89.10 and 92.18 Hz, PCH2CH2CH2CH3), 34.88 and 36.51(2×d, JPC=4.50 and 94.73 Hz, C(1)), 35.78 and 35.58 (d, 3JPC=15.38 Hz, C(4)), 35.86 (s, C(2)), 60.05 (2×d, 2JPOC=5.93 and 6.30 Hz, POCH2CH3), 73.81 and 73.97 (2×d, 3JPC=11.93 and 11.93 Hz, C(3)); 31P-NMR (121 MHz, CDCl3) δP 60.26 and 60.43; MS (CI, CH4) m/z 349.2 (100%) (MH+), 333.3 (40), 291.2 (36), 350.2 (23). Synthesis of (±)-cis-ethyl (3-hydroxycyclopentanyl)butylphosphinate (10)
