Titanocene-catalyzed alkylative dimerization of vinyl Grignard reagent using alkyl halides

摘要

Dimerization of vinyl Grignard reagents and concomitant alky-lation with alkyl halides have been achieved by using Cp_2TiCl_2 as a catalyst.rnIn the past decade, remarkable progress has been made in C-C bond forming reactions using non-activated alkyl halides, which had rarely been employed as carbon sources in conventional transition-metal-catalyzed systems. We have recently developed cross-coupling reactions and regioselective alkyla-tion reactions of C-C unsaturated compounds using alkyl halides and shown that the ate complexes of transition metals formed using Grignard reagents play an important role as active catalytic species. During the course of these studies, we have observed that Ni catalyzes regioselective 2 : 1 coupling of vinyl Grignard reagents with alkyl halides or cyclic ethers to afford alkylated homoallylic Grignard reagents 1 (Scheme 1).