To a stir red solution of 40m L CH2 Cl2 and 2. 4m L ( Et) 3N in an ice-bath was slowly
added 1. 6g( 100mmol) of 4 and 1. 2mL CH3COCl. The mixture was then stir red at rt for 1h
and ethylacetate was added. The organic layer was washed successively with saturated
Na2 CO3 and brine, then dried over Na2 SO4 and evaporated in v acuo. The solid residue was
recrystallized f rom alcohol to afford an off-white solid 1 1. 9g, yield 91% , m. p. 125℃~
127℃ . IR: υ= 3460, 1695, 1550, 795, 690cm- 1.