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Scope and Limitations of Chiral B -[3,5-Bis(trifluoromethyl)phenyl]oxazaborolidine Catalyst for Use in the Mukaiyama Aldol Reaction

2000; American Chemical Society; Volume: 65; Issue: 26 Linguagem: Inglês

10.1021/jo001271v

1520-6904

Kazuaki Ishihara, Shoichi Kondo, Hisashi Yamamoto,

Carbohydrate Chemistry and Synthesis

A new chiral oxazaborolidine catalyst was prepared in situ from 3, 5-bis(trifluoromethyl)phenylboron dichloride and N-(p-toluenesulfonyl)-(S)-tryptophan. This catalyst is much more active than Corey's original catalyst for the Mukaiyama aldol reaction of aldehydes with silyl enol ethers. The observed syn selectivities and re-face attack of silyl enol ethers on carbonyl carbon of aldehydes imply that the extended-transition state model is applicable.