Addition reactions of heterocyclic compounds. Part XXXVIII. Cycl[3,2,2]azines and indolizines from pyridines and methyl propiolate

Abstract

Pyridine and its 3- and 4-methyl- and 3,5-dimethyl-derivatives with methyl propiolate gave indolizines and cycl-[3,2,2]azine esters, identified largely from their mass, n.m.r., and u.v. spectra. The formation of these products is discussed. The cyclazine from pyridine has been degraded to 1-methylcycl[3,2,2]azine, the n.m.r. spectrum of which has been fully analysed. 4-Methylpyridine also gave 1,4-dihydro-1-(2-methoxycarbonyl-trans-vinyl)-4-(3-methoxycarbonylprop-2-enylidene)pyridine.