Stereoselective Synthesis of (<i>Z</i>)- and (<i>E</i>)-Allylic Silanes by Copper-Mediated Substitution Reactions of Allylic Carbamates with Grignard Reagents
作者:Jacqueline H. Smitrovich、K. A. Woerpel
DOI:10.1021/jo991312r
日期:2000.3.1
Both (Z)- and (E)-allylic silanes were prepared with high stereoselectivity by the copper-mediated substitution of allylic carbamates by organometallic reagents. The reaction of alkylmagnesium reagents with (E)-allylic carbamates provides (Z)-allylic silanes, whereas both alkylmagnesium and alkyllithium reagents react with (Z)-allylic carbamates to afford (E)-allylic silanes. Because Grignard reagents
(Z)-和(E)-烯丙基硅烷都通过有机金属试剂通过铜介导的烯丙基氨基甲酸酯的铜取代而以高立体选择性制备。烷基镁试剂与(E)-烯丙基氨基甲酸酯的反应提供(Z)-烯丙基硅烷,而烷基镁和烷基锂试剂都与(Z)-烯丙基氨基甲酸酯反应以提供(E)-烯丙基硅烷。由于格氏试剂通常比烷基锂种类更易于制备,因此这些试剂是合成(Z)-和(E)-烯丙基硅烷的最佳亲核试剂。该方法还允许容易获得的非外消旋烯丙基氨基甲酸酯以高的立体选择性转化为手性,非外消旋(Z)-和(E)-烯丙基硅烷。