Boron trifluoride etherate → 6-(2-Chloro-5-((2S,3R,4R,5S,6R)-3,4,5-tris(benzyloxy)-6-((benzyloxy)methyl)tetrahydro-2H-thiopyran-2-yl)benzyl)-2,3-dihydrobenzo[b][1,4]dioxine

Participants

Reaction Conditions

Reaction Steps

To a stirred −15° C. solution of lactol (125, 410 mg, 0.50 mmol) in dichloromethane/acetonitrile (4 mL/4 mL) was added triethylsilane (0.49 mL, 3.02 mmol) followed by boron trifluoride diethyl etherate (0.26 mL, 2.01 mmol) at a rate such that the reaction temperature was maintained between −15 and 0° C. The solution was allowed to warm to 0° C. over 0.5 h prior to quenching with saturated sodium bicarbonate solution. After removal of organic volatiles under a reduced pressure, the residue was partitioned between ethyl acetate and water. Following extraction of the aqueous layer with ethyl acetate, the combined organic layers were washed with brine, dried over magnesium sulfate, filtered and concentrated in vacuo. The crude residue was purified by silica gel chromatography (silica gel, 3 to 25% ethyl acetate in hexane) to yield the title compound (126, 215 mg, 0.27 mmol, 53%) as a white solid.

Provenance & Evidence