Abstract
Reaction of ethyl propiolate with benzylidenemalononitrile 1a in the presence of L-proline was observed to produce the pyran derivative 7 in 80% yield. In contrast, diethyl acetylenedicarboxylate (6b) does not react with 1a in presence of L-proline. However when DABCO is used as the amine nucleophile, 6b reacts with 1a to form diethyl 5-amino-4,6-dicyano-3-phenyl-2,3-phthalate (20a). The structures of 7 and 20a were assigned by using X-ray crystallographic analysis. 2-aminoprop-1-ene-1,1,3-tricarbonitrile (28) reacts with diethyl acetylenedicarboxylate (6b) to yield (4-Cyano-5-dicyanomethyl-2-oxo-1,2-dihydro-pyrrol-3-ylidene)-acetic acid ethyl ester (31) whose structure was confirmed by X-Ray crystal structure.