Enantioselective Cyanosilylation of α,α-Dialkoxy Ketones Catalyzed by Proline-Derived in-Situ-Prepared <i>N</i>-Oxide as Bifunctional Organocatalyst
作者:Bo Qin、Xiaohua Liu、Jian Shi、Ke Zheng、Haitao Zhao、Xiaoming Feng
DOI:10.1021/jo062336i
日期:2007.3.1
Bifunctional N,N‘-dioxide catalysts have been developed for highly enantioselective cyanosilylation of α,α-dialkoxy ketones. This process, catalyzed by in-situ-prepared proline-derived N,N‘-dioxide 2b, produced the corresponding cyanohydrin trimethylsilyl ethers in excellent yields (up to 99%) with high enantioselectivities (up to 93% ee). A reasonable mechanism was proposed according to the observation
双官能N,N- '二氧化物催化剂已经被开发用于α的高度对映选择性的硅氰化反应,α二烷氧基酮。此过程中,通过催化的原位制备的脯氨酸衍生Ñ,Ñ '二氧化物2b中,所产生的相应的氰醇三甲基甲硅烷基醚以优良产率(高达99%)的高对映选择性(高达93%ee)的。根据线性效应,1 H NMR谱图,分离的氰醇以及催化剂的NH和N-氧化物部分的作用,提出了合理的机理。