Studies with Polyfunctional Hetero Aromatics and Aromatics: Synthesis of Tetraand Penta-Substituted Benzoic and Phthalic Acid Derivatives Through Reactions of Acetylenic Esters or Diesters with Arylidenemalononitriles in the Presence of LProline or DABCO.

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.