Rhodium(I)-Catalyzed Sequential C(sp)-C(sp(3)) and C(sp(3))-C(sp(3)) Bond Formation through Migratory Carbene Insertion.

A Rh(I)-catalyzed three-component reaction of tert-propargyl alcohol, diazoester, and alkyl halide has been developed. This reaction can be considered as a carbene-involving sequential alkyl and alkynyl coupling, in which C(sp)-C(sp(3)) and C(sp(3))-C(sp(3)) bonds are built successively on the carbenic carbon atom. The Rh(I)-carbene migratory insertion of an alkynyl moiety and subsequent alkylation are proposed to account for the two separate C-C bond formations. This reaction provides an efficient and tunable method for the construction of all-carbon quaternary center.