Cyclising nucleophilic addition to azinium systems. Part 1. Reaction of 3-indol-2-ylpyridine, 3-indol-2-ylquinoline, 4-indol-2-ylisoquinoline and pyrido[3,4-a]carbazoles with acetic anhydride

Abstract

Two pyrido[3,4-a]carbazoles were shown to react smoothly with acetic anhydride to give 1-acetyl-1,12a-dihydro[1,6]naphthyridino[4,6-aml]carbazol-11(12H)-ones. 3-Indol-2-ylquinoline and 3-indol-2-ylpyridine reacted in an analogous fashion though with further complications in the latter case. 4-Indol-2-ylisoquinoline gave E-2-acetyl-1-(1-acetylindol-2-ylmethylene)-2,3-dihydro-3-(2-oxopropyl)-1H-isoindole, the structure of which was determined by a detailed study of its ¹H n.m.r. spectrum with decoupling, n.O.e. and relaxation time measurements.