A-acetoxy-p-ketosulfides

The highly enantioselective organocatalytic rearrangement of racemic a-acetoxy-P-ketosulfides (compounds that are easily obtained by Pummerer rearrangement of P-ketosulfoxides) to a-acetoxythioesters was reported by Frongia and coworkers in 2010 [36]. The process, which is formally a l,4-0,0 rearrangement of an acetyl group, can be conveniently catalyzed by quinidine 22 (Scheme 40.32). The proposed catalytic cycle, depicted in Scheme 40.33, involves the deprotonation of the... 

Scheme 40.32 Quinidine-catalyzed rearrangement of a-acetoxy-p ketosulfides to...

P-sulfonyl 857 a-acetoxy-P-ketosulfides 1207 -racemic 1207 a-acetoxythioesters 1207 N-acetylaminomalonate 502 acetylenes 1207... 

Scheme 40.33 Proposed mechanistic cycle for the rearrangement of a-acetoxy-P-ketosulfides.

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