title: Initiation and termination mode of enyne cross-metathesis and metallotropic [1,3]-shift controlled by remote substituents.
abstract: 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.
authors.affiliation: Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607-7061, USA.
authors.forename: Sang Young
authors.initials: SY
authors.lastname: Yun
authors.forename: Kung-Pern
authors.initials: KP
authors.lastname: Wang
authors.forename: Mansuk
authors.initials: M
authors.lastname: Kim
authors.forename: Daesung
authors.initials: D
authors.lastname: Lee