Substituted indolizines and indenoindolizines

Abstract

Indolizines, indeno[1,2-g]indolizine, and indeno[1,2-e]indolizine containing benzoyl and carbomethoxy groups in the five-membered ring were obtained, respectively, by condensation of ring-substituted N-phenacylpyridinium bromide and the analogous 3-methyl-2-azafluorenium bromide quaternary salts, as well as 4-azafluorenium bromide, with dimethyl acetylenedicarboxylate in the presence of triethylamine. A substituted indeno[2,3-f]indolizine was obtained from the analogous quaternary 9-oxo-3-methyl-2-azafluorenium quaternary salt by the Chichibabin method. 9-Oxo-3-methyl-2-azafluorenium dibenzoylmethylid and 5-oxo-2-phenyl-3-benzoylindeno[2,3-f]indolizine were also synthesized. Deuterium exchange in 9-oxo-3-methyl-2-phenacyl-2-azafluorenium bromide was studied by means of PMR spectroscopy, and information regarding the protonation of the substituted indeno[2,3-f]indolizines was obtained.