CYANO-0-PHENYLACRYLIC AciD

A. Esterification of a-Cyano-0-Phenylacrylic Acid — In a 200-cc. round-bottom flask fitted with a reflux condenser, 50 g. of dry a-cyano-0-phenylacrylic acid (Org. Syn. 7, 20) is boiled for four and a half hours with 100 cc. of absolute alcohol containing 3-4 g. of anhydrous hydrogen chloride. The resulting solution is filtered rapidly while hot and allowed to stand overnight. Long, flat, colorless prisms separate which are filtered off with suction, washed with a little cold alcohol and dried in air. A further small quantity may be obtained by working up the mother liquor. The melting-point of the ethyl a-cyano-/3-phenylacrylate is 50° and the yield 46.5-53 g. (82-94 per cent of the theoretical amount). 

Reaction of l-aryl-3-carbethoxy-6-phenyl-l,4,5,6-tetrahydropyridazin-4-ones 718 with activated olefins such as benzalacetophenone, benzalacetone, 3-benzylideneacetylacetone, diethyl 2-benzylidenemalonate, and a-cyano-/3-phenylacrylic acid in the presence of an organic base like pyrrolidine, morpholine, piperidine, or triethylamine gave the corresponding 2,8-dihydro-l//-pyrano[2,3-t7 pyridazines 719-723, respectively. The 1-oxo- and 1-imino derivatives of the pyrano[2,3-r/ pyridazine ring system were also prepared from the respective 6-oxo or 6-imino derivative of the starting pyridazine 718 under the same conditions (Equation 60) <1989IJB733>. 

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