Construction of the azepinoindole core tricycle of the Stemona alkaloids

Article abstract of DOI:10.1021/jo980916c

The azepinoindole substructure common to a number of Stemona alkaloids is constructed by employing a 7-endo radical cyclization of a readily available N-alkylated hydroindolone substrate. The indolone precursors are prepared via [1 + 4] cycloaddition between a vinyl isocyanate and either dimethoxycarbene or cyclohexylisocyanide.