Imidazole → (-)-(1R,2S)-2-phenyl-1-cyclohexyl triisopropylsilyloxyacetate

Participants

Reaction Steps

A solution of (−)-(1R,2S)-2-phenyl-1-cyclohexyl hydroxyacetate (851 mg, 3.63 mmol) was prepared through esterification of benzyloxyacetyl chloride with (−)-(1R,2S)-2-phenyl-1-cyclohexanol followed by hydrogenolysis. Then, triisopropylsilyl chloride (840 mg, 4.36 mmol) and imidazole (618 mg, 9.08 mmol) in dimethylformamide (DMF) (1.7 mL) was added and stirred at room temperature for 12-20 hours. The mixture was poured into pentane (25 mL), and washed with water and brine. The combined organic layers were dried over anhydrous MgSO4 and concentrated in vacuo. The crude product was subjected to a purification on a short silica gel column using hexane/chloroform (3/1) as the eluant to give pure (−)-(1R,2S)-2-phenyl-1-cyclohexyl triisopropylsilyloxyacetate (1.35 g, 95% yield) as a colorless oil: [α]D20−17.1° C. 3.15, CHCl3); IR (neat) 1759, 1730 (nCO) cm−1; 1H NMR (CDCl3) δ0.93-0.99 (m, 21H), 1.30-1.62 (m, 4H), 1.72-2.0 (m, 3H), 2.10-2.19 (m, 1H), 2.66 (dt, J=11.5, 4.0 Hz, 1H), 3.90 (d, J=16.6 Hz, 1H), 4.07 (d, J=16.6 Hz, 1H), 5.07 (dt, J=10.6, 4.0 Hz, 1H), 7.16-7.30 (m, 5H). Anal. Calcd for C23H38O3Si: C, 70.72; H, 9.81. Found: C, 70.79; H, 9.85.

Provenance & Evidence