A HYDROCARBON STRUCTURE-REACTIVITY STUDY IN ADMET CHEMISTRY .1. 1,1-DISUBSTITUTED AND TRISUBSTITUTED OLEFINS

The ADMET chemistry of 1,1-disubstituted, 1,2-disubstituted, and trisubstituted alkenes has been examined in the presence of the Lewis acid free metathesis catalysts M(CHR')(NAr)(OR)(2) where M = W (1) or Mo (2), Ar = 2,6-(i-Pr)(2)C6H3, R' = CMe(2)Ph, and R = CMe(CF3)(2), and the specific interaction of each olefin with the catalysts has been monitored by H-1 NMR. Successful metathesis depends on both the substitution pattern of the olefin and the catalyst employed. The molybdenum-based catalyst promotes the methathesis of 1,1-disubstituted alkenes but only through cross-metathesis with internal olefins which are no greater than disubstituted. The tungsten-based catalyst is unable to promote metathesis chemistry with these substituted olefins.