Enantioselective dirhodium(II)-catalyzed cyclopropanations with trimethylsilylethyl and trichloroethyl aryldiazoacetates
作者:Solymar Negretti、Carolyn M. Cohen、Jane J. Chang、David M. Guptill、Huw M.L. Davies
DOI:10.1016/j.tet.2015.05.045
日期:2015.9
readily prepared by rhodium-catalyzed cyclopropanation of alkenes with aryldiazoacetates and styryldiazoaceates, in which the ester functionality is either trimethylsilylethyl (TMSE) or trichloroethyl (TCE). By having labile protecting groups on the ester, chiral triarylcyclopropane carboxylate ligands were conveniently prepared. The asymmetric induction during cyclopropanation is dependent on the
通过用芳基重氮乙酸酯和苯乙烯基二重氮酸酯对烯烃进行铑催化的环丙烷化,可以轻松制备高度官能化的环丙烷羧酸酯,其中酯官能度为三甲基甲硅烷基乙基(TMSE)或三氯乙基(TCE)。通过在酯上具有不稳定的保护基,可以方便地制备手性三芳基环丙烷羧酸酯配体。环丙烷化过程中的不对称诱导取决于酯基和手性四羧酸四氢吡啶鎓催化剂的性质。脯氨酸盐催化剂Rh 2(S -DOSP)4是TMSE重氮酯与苯乙烯不对称分子间环丙烷化的最佳催化剂,而Rh 2(R -BPCP)4 是TCE重氮酯的最佳催化剂。