Amide-substituted diynes were cyclized in the presence of a cationic gold catalyst and an external nucleophile leading to 1-indenones and 1-iminoindenones. The electron-donating features of the nitrogen atom enable the formation of a reactive ketene iminium ion, which can be trapped by either diphenyl sulfoxide or anthranil as nucleophiles in a subsequent oxidation step, providing substituted inden-1-on-3-carboxamides.
Keywords: cyclization; diphenylsulfoxide; diynes; gold; ynamides.
© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.