反应详情

A solution of compound 31 (160 g, 1.30 mol) and 2,2′-dimethoxypropane (207 g, 1.90 mol) in dry acetone (800 mL) was added p-TsOH (9.2 g, 0.053 mol) under N2 and stirred at RT for 12 h. To this was added triethylamine drop-wise to neutral pH and then concentrated under vacuum below 35° C. The crude residue was purified by column chromatography over neutral alumina (12% ethyl acetate in pet. ether) to give the title compound (84 g, 39%). TLC: Pet. ether/EtOAc, 1:1, Rf=0.2

1. concentrationconcentrated under vacuum below 35° C
2. customThe crude residue was purified by column chromatography over neutral alumina (12% ethyl acetate in pet. ether)