1,3-Dipolar cycloaddition reaction of benzodiazinium and naphthyridinium N-imines with acetylenic esters

1,3-Dipolar cycloaddition of N-imines derived from mono-N-amino salts of phthalazines, 2-phenylquinoxaline, 1,5- and 1,8-naphthyridines with dimethyl acetylenedicarboxylate: and methyl propiolate resulted in the formation of new tricyclic: heterocyclic ring systems with bridgehead nitrogen.