Catalytic formal [4 + 1] isocyanide-based cycloaddition: an efficient strategy for the synthesis of 1<i>H</i>-cyclopenta[<i>b</i>]quinolin-1-one derivatives

Abstract

An unprecedented catalytic isocyanide-based cycloaddition of alkyl and aryl isocyanides with (Z)-2-(2-hydroxy-2-alkylvinyl)quinoline-3-carbaldehydes was developed for the direct and efficient synthesis of 1H-cyclopenta[b]quinolin-1-one derivatives. On the basis of DFT calculations, a mechanism is proposed involving formal [4 + 1] cycloaddition of isocyanides, followed by imine-enamine tautomerization and air oxidation.