[2+1] Cycloaddition of Catalytic Ruthenium Vinyl Carbenes: A Stereoselective Controlled Access to (Z)- and (E)-Vinyl Epoxypyrrolidines

Abstract: Aza-alkynals undergo a cyclization reaction with diazo compounds in the presence of catalytic amounts of Cp*RuCl(cod) to afford vinyl epoxypyrrolidines, valuable building blocks for the synthesis of biologically active molecules. Ruthenium vinyl carbene intermediates have been invoked to explain the overall [2 + 1] cycloaddition (epoxy-annulation reaction). The reaction proceeds under mild conditions and in short reaction times (5-80 min) with complete (Z)- or (E)-stereoselectivity on the vinyl substituent, depending on the nature of the diazo compound used. Theoretical calculations support a mechanistic rationale to explain this controlled process.

Author(s): Padin, D; Cambeiro, F; Fananas-Mastral, M; Varela, JA; Saa, C

ACS CATALYSIS

DOI: 10.1021/acscatal.6b02929