反应详情

3.93 ml (18.6 mmol) of hexamethyldisilazane was dissolved in 20 ml of anhydrous THF. To the resultant solution was added 11.2 ml (18.3 mmol) of a solution of 1.66M butyllithium in hexane in a stream of argon gas at -10° C., and the resultant mixture was stirred for 20 minutes. 1.86 ml (18.6 mmol) of anhydrous ethyl acetate was added to the mixture at -78° C., and the resultant mixture was stirred for 20 minutes. A solution of 3.8 g (15.5 mmol) of compound 3 obtained in Reference Example 3 in 20 ml of anhydrous THF was dropwise added to the mixture and the resultant mixture was stirred at -78° C. for 2 hours to effect a reaction. To the obtained mixture was added a saturated aqueous ammonium chloride solution to thereby terminate the reaction and then, the resultant mixture was concentrated under reduced pressure to thereby obtain a residue. Water was added to the obtained residue, and ethyl acetate was further added for extraction to obtain an organic layer. The organic layer was separated, washed with saturated saline, dried over anhydrous sodium sulfate, and concentrated under reduced pressure to thereby obtain a residue. The obtained residue was purified by silica gel column chromatography (the composition of the developing solvent was; ethyl acetate:hexane=2:1 to 1:2). As a result, 4.1 g of compound 32a (12.3 mmol, yield: 79%) was obtained as a colorless oily product and 485 mg of compound 32b (1.46 mmol, yield: 9.4%) was obtained as a yellow crystalline product.