A solution of oxalyl chloride (0.24 ml) in methylene chloride was cooled to -78° C., followed by addition of DMSO (0.44 ml). After 15 minutes, a solution of the diol (41) (0.358 g) in methylene chloride was added dropwise to the resultant mixture. After 30 minutes, the mixture was warmed to -50° C., followed by stirring for 1.5 hours. Then, the reaction mixture was allowed to warm to -35° C. and triethylamine (0.88 ml) was added thereto. The crude product obtained after the usual work-up was subjected to silicagel column chromatography to give the diketone (42).
