Rh(I)-Catalyzed Regio- and Enantioselective Ring Opening of Vinyl Cyclopropanes

Webster SJ, Balázs LB, Goetzke FW, Stojalnikova V, Liu K, Christensen KE, Mackenzie HW, Fletcher SP

We describe a Rh­(I) catalyzed asymmetric ring opening of racemic vinyl cyclopropanes using aryl boronic acids as C-nucleophiles. When ferrocene-based chiral bisphosphines are used as ligands, the products are obtained with regioselectivities typically 99:1 r.r. and ee’s generally between 88 and 96%. A wide range of aryl boronic acids can be used, and the products can be converted into a variety of targets. Preliminary mechanistic studies indicate that Zn­(OTf)2 plays a significant role in the reaction by promoting rhodium-ligand complex formation and accelerating the reaction. We expect this method and these mechanistic insights to be useful in the development of new asymmetric methods.