Heterocyclic compounds with bridgehead nitrogen atoms. Part III. The formation of cyclopenta[c]quinolizines from 3-α-dimethyl-aminovinylindolizines and dimethyl acetylenedicarboxylate

Abstract

2-Alkyl- and 2-aryl-indolizines react with NN-dimethylacetamide, in presence of phosphoryl chloride, to give 3-α-dimethylaminoethylideneindolizinium salts. The enamines derived from the salts by proton-loss react with dimethyl acetylenedicarboxylate in boiling toluene to give dimethyl cyclopenta[c]quinolizinedicarboxylates. The intermediate compounds in this rearrangement have been isolated and the substitution reactions of the cyclopenta[c]quinolizine nucleus have been studied.