Carbomagnesiation Reactions

Abstract

Introduction Carbomagnesiation Reactions of Alkynes Carbomagnesiation Reactions of Alkenes Carbomagnesiation Reactions of Aromatics Summary

Rhodium-Catalyzed Arylzincation of Alkynes: Ligand Control of 1,4-Migration Selectivity

“…In the reactions of alkyl­(aryl)­alkynes 2e – 2f , high regioselectivity was observed for the bond formation between the aryl group of the arylzinc and the alkyl-substituted alkyne carbon (entries 5 and 6). This selectivity is as expected from the reported regiochemistry at carbometalation of alkyl­(aryl)­alkynes . The high regioselectivity was also observed in the arylzincation of methyl­(alkyl)­alkyne 2g , where the alkyl group is much bigger than methyl (entry 7).…”

“…Carbometalation of alkynes is one of the most efficient methods of generating substituted alkenylmetals which are useful synthetic intermediates for the multisubstituted alkenes, and addition of arylmetals to simple unfunctionalized alkynes has been a challenging reaction because of their low reactivity . The first-row transition metals including Ni, Co, Fe, Mn, and Cr have been reported to catalyze the addition of arylmagnesium and -zinc reagents to the unfunctionalized alkynes (Scheme a).…”

Silver-Catalyzed Regioselective Carbomagnesiation of Alkynes with Alkyl Halides and Grignard Reagents

“…The addition of Grignard reagents to alkynes, i.e., carbomagnesiation, yields vinyl Grignard reagents 1 with the concomitant formation of a new C–C bond and a C–Mg bond (Scheme , route A) . Combinations of this reaction and subsequent trapping with electrophiles or metal-catalyzed coupling provide a useful and practical method for the synthesis of multisubstituted alkenes 2 .…”