To a solution of oxalyl chloride (72 μl, 0.83 mmol) in methylene chloride (1 ml) under an argon atmosphere and cooled in a dry ice-acetone bath was added dimethylsulfoxide (0.12 ml, 1.65 mmol) with stirring. After 5 minutes, a solution of the compound of example 57 (0.25 g, 0.55 mmol) in methylene chloride (1.5 ml) was added. The reaction mixture was stirred for 15 minutes, triethylamine (0.50 ml, 3.58 mmol) then added and the reaction warmed to room temperature for 30 minutes. The reaction mixture was placed directly onto a silica gel column and eluted with methylene chloride-methanol. Trituration of the resultant oily solid with ether-hexane and filtration gave the above-named product, (50 mg, 0.11 mmol).
