Synthesis of tri- and tetracyclic condensed quinoxalin-2-ones fused across the C-3 - N-4 bond

摘要

We have studied the preparation of some fused quinoxalinones by Stevens rearrangement of a spiro-quinoxaline-derived ammonium ylide or by treatment of N-(2,4-dinitrophenyl)-and N-(2-nitrophenyl)imino acids with different reducing agents. We have reinvestigated and clarified some related processes found in the literature starting from imino acids derivatives. Additional reactions of the fused quinoxalinones, as well as the useful dehydrogenation/decarboxylation of some easily available 1-arylindoline-2-carboxylic acids to the corresponding 1-arylindoles, are also reported. © Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.