Reaction between 3H-pyrrolizines and acetylenedicarboxylic esters. Part III. The photochemical reaction

Abstract

The photochemical addition of dimethyl acetylenedicarboxylate to 3H-pyrrolizine (1) and to 3,3-dimethyl-3H-pyrrolizine (7) gave low yields of 7-azatricyclo[5,3,0,0]decatriene-3,4-dicarboxylates (4) and (10). The former reaction also gave the 8-maleate and 8-fumarate derivatives (5) and (6). Thermal ring opening of compound (10) gave dimethyl 5,5-dimethyl-5H-pyrrolo[1,2-a]azepine-7,8-dicarboxylate (11); photochemical reaction gave a dimer (13). Attempts to prepare 5-methyl-3H-pyrrolizine (14) gave a mixture containing a 1H-pyrrolizine (16); reaction of 3-ethoxycarbonylmethylene-3H-pyrrolizine (23) with dimethyl acetylenedicarboxylate gave the cycl[3,2,2]azine (pyrrolo[2,1,5-cd]indolizine) triester (25).