Phosphine-catalyzed [3 + 2] cycloaddition of phthalazinium dicyanomethanides with allenoates: highly efficient synthesis of 1,2,3,10b-tetrahydropyrrolo[2,1-a]phthalazine derivatives

Abstract

The phosphine-catalyzed [3 + 2] cycloaddition between phthalazinium dicyanomethanides and allenoates, has been achieved in dichloromethane at room temperature, providing a broad range of novel heterocyclic compounds, 1,2,3,10b-tetrahydropyrrolo[2,1-a]phthalazine derivatives, as single (Z)-isomers in excellent yields (88–99% yield). All reactions are operationally simple and proceed very fast under mild reaction conditions.