Evans-Akiba reaction

Evans [211] and Akiba [212] reported in 1996 and 1997, respectively, that some pentacoordinated phosphorane-stabilized carbanions could undergo olefination with aldehydes, which we suggest be called the Evans-Akiba reaction. Similar to the HWE and Homer-Wittig reactions, this reaction has been proposed by Akiba et al. to proceed through diastereoselective carbonyl addition, cyclization, and elimination to yield an alkene (Scheme 45) [213-216]. It is noteworthy that the phosphoms atom is hexacoordinated in the four-center transition state. 

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