Acyclic stereocontrol in Fischer carbene chemistry by syn-selective Michael addition/trapping sequence
作者:Eiichi Nakamura、Koichi Tanaka、Tsutomu Fujimura、Satoshi Aoki、Paul G. Williard
DOI:10.1021/ja00073a017
日期:1993.10
Michaeladdition of a metal enolate to a Fischer vinyl carbene complex 1 takes place with syn-diasterselectivity. The resulting anion 2 can be trapped stereoselectively to afford a carbene complex 3 with stereocontrol of three contiguous stereogenic centers. The syn-diastereoslectivity of the Michaeladdition was unaffected either by the geometry or the countercation of the enolate. Lewis acidic metal
金属烯醇化物与 Fischer 乙烯基卡宾配合物 1 的迈克尔加成以顺对映选择性发生。生成的阴离子 2 可以立体选择性地被捕获,以提供具有三个连续立体中心立体控制的卡宾配合物 3。迈克尔加成的同向非对映选择性不受烯醇化物的几何形状或反阳离子的影响。路易斯酸性金属反阳离子减慢迈克尔加成。路易斯酸介导的向山-迈克尔加成烯醇甲硅烷基醚也失败。1 H 和 13 C NMR 研究表明 SnCl 4 与乙烯基卡宾络合物 1a 没有络合
Erythro selective aldol condensation using titanium enolates