反应详情

Compounds 20a and 20b (each, 3.73 mmol) obtained in Reference Example 14 were individually dissolved in 20 ml of anhydrous tetrahydrofuran. To each of the resultant solutions was added a solution of 0.93M diisobutylaluminumhydride in hexane (7.46 mmol) in a stream of argon gas at -78° C. Each of the resultant mixtures was stirred at -78° C. for 1 hour to effect a reaction. 1N hydrochloric acid was added to each of the reaction mixtures to thereby terminate the reaction. The resultant mixture was subjected to distillation under reduced pressure to thereby remove the solvent and obtain a residue. Water was added to each of the obtained residues, and ethyl acetate was further added for extraction to thereby obtain an organic layer. Each of the organic layers was separated, washed with saturated saline, dried over anhydrous sodium sulfate, and concentrated under reduced pressure to thereby obtain a residue. Each of the obtained residues was purified by silica gel column chromatography (the composition of the developing solvent for the residue obtained from compound 20a was; ethyl acetate:hexane =1:1, and the composition of the developing solvent for the residue obtained from compound 20b was; ethyl acetate:hexane=1:2). As a result, compound 21a was obtained from compound 20a (yield: 95%), and compound 21b was obtained from compound 20b (yield: 99%).