Unexpected Tandem Ylide Annulation Reaction for Controllable Synthesis of 2<i>H</i>-Chromenes and 4<i>H</i>-Chromenes

Abstract

[reaction: see text] An unexpected tetrahydrothiophene-catalyzed ylide annulation reaction, via tandem Michael addition/elimination/substitution, for the controllable synthesis of 2H-chromenes and 4H-chromenes has been developed.