To a room temperature solution of 2.49 g of product from Example 83, 1.27 ml of pyridine and 30 ml of methylene chloride is added, dropwise, 0.985 g of acetyl chloride. The reaction is stirred at room temperature for 1.5 hours, poured into saturated sodium bicarbonate and extracted with methylene chloride. The organic layer is washed with saturated sodium chloride, dried and concentrated in vacuo. The residue is purified by chromatography (silica gel: 95% ethyl acetate/hexane) to give 2.65 g of the desired product as a yellow oil.
