Ni(II) Salts and 2-Propanol Effect Catalytic Reductive Coupling of Epoxides and Alkynes

A Ni-catalyzed reductive coupling of alkynes and epoxides using Ni(II) salts and simple alcohol reducing agents is described. Whereas previously reported conditions relied on Ni(cod)(2) and Et3B, this system has several advantages including the use of air-stable and inexpensive Ni(II) precatalysts (e.g., NiBr2 center dot 3H(2)O) as the source of Ni(0) and simple alcohols (e.g., 2-propanol) as the reducing agent. Deuterium-labeling experiments are consistent with oxidative addition of an epoxide C-O bond that occurs with inversion of configuration.