Diethyl Ether → D-(+)-Glucal

Participants

Reaction Conditions

Reaction Steps

Galactal 7′ (0.100 g, 0.304 mmol) in 5 mL dry CH2Cl2 at 0° C. under a N2 atmosphere was treated with 10 mL Murray solution (freshly prepared) and stirred at 0° C. for 40 min. TLC (1:1 EtOAc:hex) showed no trace of 7′. Solvents were evaporated using a dry N2 stream. The residual epoxide of 7′ was kept on a vac. line ˜2 h. To the epoxide under a N2 atmosphere was added a solution of glucal derivative 3′ (0.150 g, 0.496 mmol) in 3 mL dry THF. On cooling to −78° C., 1.0 M ZnCl2 in Et2O (0.50 mL, 0.50 mmol) was added. The mixture was allowed to slowly warm to r.t. (over ˜2 h) and stirred overnight. TLC (1:1 EtOAc:hex) showed that the reaction was complete. Saturated aq. NaHCO3 (20 mL) was added, and the mixture was then extracted with EtOAc (3×20 mL). The organic layer was dried over MgSO4. Column chromatography on silica (1:3 EtOAc:hex) afforded diol 18′ as a colorless solid. Yield: 173 mg (89%). [α]D23−9.8° (c 1.0, CH2Cl2).

Provenance & Evidence