Synthesis of Extended Oxazoles III: Reactions of 2-(Phenylsulfonyl)methyl-4,5-diaryloxazoles.

2-((Phenylsulfonyl)methyl)-4,5-diphenyloxazole is a useful scaffold for synthetic elaboration at the 2-methylene position thereby affording extended oxazoles. The corresponding α-sulfonyl anion reacts smoothly with diverse alkyl halides giving monoalkylated (47-90%), dialkylated (50-97%), and cyclic (59-93%) products. The reductive desulfonylation of the monoalkylated and selected dialkylated products was optimized with a magnesium/mercuric chloride reagent system and afforded desulfonylated products in the range of 66-97%. The anti-inflammatory Oxaprozin was prepared using the α-sulfonyl carbanion strategy along with optimized desulfonylation.