Harada Hitoshi, Thalji Reema K, Bergman Robert G, Ellman Jonathan A
Department of Chemistry, University of California, and Division of Chemical Sciences, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
J Org Chem. 2008 Sep 5;73(17):6772-9. doi: 10.1021/jo801098z. Epub 2008 Aug 6.
Highly enantioselective catalytic intramolecular ortho-alkylation of aromatic imines containing alkenyl groups tethered at the meta position relative to the imine directing group has been achieved using [RhCl(coe)2]2 and chiral phosphoramidite ligands. Cyclization of substrates containing 1,1- and 1,2-disubstituted as well as trisubstituted alkenes were achieved with enantioselectivities >90% ee for each substrate class. Cyclization of substrates with Z-alkene isomers proceeded much more efficiently than substrates with E-alkene isomers. This further enabled the highly stereoselective intramolecular alkylation of certain substrates containing Z/E-alkene mixtures via a Rh-catalyzed alkene isomerization with preferential cyclization of the Z-isomer.
使用[RhCl(coe)₂]₂和手性亚磷酰胺配体,实现了含有相对于亚胺导向基团在间位连接烯基的芳族亚胺的高度对映选择性催化分子内邻位烷基化。对于含有1,1-和1,2-二取代以及三取代烯烃的底物的环化反应,每类底物的对映选择性均>90% ee。Z-烯烃异构体底物的环化反应比E-烯烃异构体底物的效率高得多。这进一步实现了某些含有Z/E-烯烃混合物的底物通过Rh催化的烯烃异构化以及Z-异构体的优先环化反应进行高度立体选择性分子内烷基化。