Rhodium-Catalyzed Regio- and Diastereoselective Hydroarylation of Allenes: An Unprecedented Ene Reaction

Abstract

A rhodium-catalyzed nucleophilic addition of α-acidic isocyanoacetamides to allenes for the selective formation of Z-vinyl-functionalized oxazoles as an unprecedented method for hydroarylation of allenes is described. Employing diverse isocyanoacetamides and allenes, a library of vinyl oxazoles is introduced in a stereo- and regiospecific fashion and moderate to high yields. Mechanistic investigations reveal that the reaction proceeds through a concise rhodium-catalyzed ene reaction followed by reductive elimination.

Transition Metal‐Catalyzed Intermolecular Hydroarylation of Allenes

“…Balalaie and Breit reported an original rhodium‐catalyzed hydroarylation of terminal allenes leading to vinyl oxazoles, which are formed in situ through an ene reaction starting from enolisable isocyanoacetamides (Scheme 73). [70] This reaction is performed under microwave irradiation in the presence of the dimer [Rh(cod)Cl] 2 as the catalyst and DPEphos as the ligand. Sixteen variously 2,4,5‐trisubstituted oxazoles were obtained in medium to high yields following these conditions.…”