A new cross-cycloaddition reaction between a wide range of isocyanides and 2-isocyanochalcones (or analogues) was developed for the expeditious synthesis of pyrrolo[3,4-b]indoles under thermal conditions. On the basis of the experimental results and DFT calculations, a mechanism for this domino reaction is proposed involving chemoselective heterodimerization of two different isocyanides to form 1,4-diazabutatriene intermediates, followed by an intramolecular [3+2]-cycloaddition and 1,3-proton shift.
Keywords: 1,4-diazabutatriene; cross-cycloaddition; heterodimerization; isocyanides; pyrrolo[3,4-b]indoles.
© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.