Asymmetric hydrogenation of α-keto Weinreb amides has been realized with [Ru((S)-Sunphos)(benzene)Cl]Cl as the catalyst and CeCl3·7H2O as the additive. A series of enantiopure α-hydroxy Weinreb amides (up to 97% ee) have been obtained. Catalytic amount of CeCl3·7H2O is essential for the high reactivity and enantioselectivity and the ratio of CeCl3·7H2O to [Ru((S)-Sunphos)(benzene)Cl]Cl plays an important role in the hydrogenation reaction.
New Methodology for the Synthesis of <b>α,α</b>-difluoroketones
作者:Purakkattle Biju
DOI:10.1080/00397910801997637
日期:2008.5.23
Abstract A newmethodology is described for the synthesis of α,α-difluorinated ketones by the addition of organolithium reagents to α,α-difluoro-N-methoxy-N-methyl amides (Weinreb amides).