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.
Keywords: DABCO, Ethyl propiolate, L-Proline, Diethyl acetylenedicarboxylate, Benzylidenemalononitrile, 2-Aminoprop-1-ene-1, 1, 3-
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