Identification of a new product of the reaction of 3-hydroxy-2- phenylacrylonitrile with phosphorus pentabromide

Abnormal course of the reaction of 3-hydroxy-2phenylacrylonitrile (I) (one of stable enols [1]) with phosphorus pentachloride was recorded in [2]. Instead of the substitution of the hydroxy group for chlorine a chlorine-free compound is formed whose composition corresponds to a dimer of cyano(phenyl)ethenylidene. It was shown in [3] that the expected 3-chloro-2-phenylacrylonitrile might be obtained when the reaction was carried out in the presence of pyridine, and to the dimer the structure was erroneously assigned of 1,2,5,6-dibenzocyclooctatetraene-3,7-dicarbonitrile (III) [3]. Later the dimer was correctly identifi ed using NMR data as 2-phenylnaphthalene-1,4-dicarbonitrile (IV) [4].