OLEFIN METATHESIS OF ALKENYLSILANES. II. ON THE INITIATION OF OLEFIN METATHESIS WITH ORGANOSILANES

Article abstract of DOI:10.1016/0022-328X(86)80351-5

A study has been made of the cross-metathesis of alkenylsilanes CH2=CH(CH2)nSiX3 (n=1,2; X=CH3, Cl, OMe) with (Z)-2-pentene with WCl6 as the catalyst precursor.For allyltrimethylsilane (ATMS; n=1, X=CH3) the reaction proceeds without added co-catalyst but with an induction period.The catalytically-active intermediate in this case is formed by allyl-group transfer from Si to W, as revealed by the formation of ClSiMe3.Allyltrichlorosilane and allyltrimethoxysilane requires the addition of an alkylating co-catalyst, e.g.SnMe4.Addition of a Lewis acid, e.g.AlCl3 or AlBr3, show that for ATMS removes the induction period and substantially raises the activity.The initial activity and the E/Z-stereoselectivity are affected in a very similar way by the addition of the Lewis acid.The results indicate that the Lewis acid participates in the initiating, propagating, and terminating steps of the reaction.