Generation of zwitterionic trifluoromethyl N-allylic ylides and their use in switchable divergent annulations.

Abstract

The previously unreported zwitterionic N-allylic ylide species from the corresponding Morita-Baylis-Hillman carbonates of trifluoromethyl ketones and acrylonitrile are generated under the catalysis of cinchona-derived tertiary amines, and subsequently participate in switchable asymmetric [3+2] or [4+1] annulations with 1-azadienes in chemo-, regio-, and stereodivergent manners via catalyst or substrate control. A diverse range of frameworks, having a trifluoromethylated all-carbon quaternary stereogenic centre or a tetrasubstituted alkene moiety, are generally constructed in good yields with excellent enantioselectivity.