反应详情

In 150 ml of ethanol was dissolved 6.0 g of ethyl ester of 3-[N-[4-chloro-2-[2-benzyloxy-α-hydroxybenzyl]phenyl]-N-isobutylcarbamoyl]acrylic acid, as obtained in (4), to which was added 3.18 g of potassium carbonate; the mixture was then stirred overnight. The solvent was distilled off under reduced pressure, and the residue was subjected to extraction with 150 ml of water and 200 ml of ethyl acetate. The ethyl acetate layer was washed with water and dried over anhydrous magnesium sulfate, then distilled off under reduced pressure. The residue was purified by means of silica gel column chromatography (eluent, hexane:ethyl acetate=5:1) to yield 5.8 g of ethyl ester of trans-5-(2-benzyloxyphenyl)-7-chloro-1-isobutyl-2-oxo-1,2,3,5-tetrahydro-4,1-benzoxazepine-3-acetic acid as prism crystals, m.p. 146° to 147° C.