Initiation and termination mode of enyne cross-metathesis and metallotropic [1,3]-shift controlled by remote substituents.
The cross-metathesis of terminal alkyne and alkene using Ru-based Grubbs catalyst generally undergoes alpha-insertion. In this study, excellent control over alpha- and beta-insertion of ruthenium alkylidene into terminal alkynes has been achieved by using a substituent at a remote site from the reaction center. While the origin of this regioselectivity of insertion and metallotropic shift remains to be established, the trend indicates that the alpha-insertion with a concomitant metallotropic shift is favored with small substituents whereas the beta-insertion without a metallotropic shift is favored with bulky substituents such as tert-butyl and trialkyl silyl groups.
Yun
Sang Young
SY
Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607-7061, USA.
Wang
Kung-Pern
KP
Kim
Mansuk
M
Lee
Daesung
D