Cobalt Catalysis Enables Regioselective Ring-opening of Epoxides with Aryl Halides

Abstract

Ring-opening of epoxides furnishing either linear or branched products belongs to the group of classic transformations in organic synthesis. However, the regioselective cross-electrophile coupling of aryl epoxides with aryl halides still represents a key challenge. Herein, we report vitamin B12/Ni dual-catalytic system that allows for the selective synthesis of linear products under blue-light irradiation.

Recent Progress on Transition-Metal-Mediated Reductive C(sp3)–O Bond Radical Addition and Coupling Reactions

“…Gryko has shown that a photo-induced Ni and VB 12 dual catalytic method was suitable for regioselective epoxide ring opening/arylation at the sterically less hindered site, analogous to that of the iodide substitution process (Scheme 3c ). 12 The nucleophilic ring opening of an epoxide by a Co(I) catalyst based on VB 12 generates an alkyl–Co(III) intermediate, which undergoes homolysis to give an alkyl radical and a Co(II) species under blue light irradiation. Reduction of Co(II) regenerates Co(I).…”