Nucleophilic attacks on carbon–carbon double bonds. Part XVIII. Reaction of 2-dicyanomethyleneindane-1,3-dione with anilines in acetonitrile

Abstract

The replacement of one of the cyano-groups of 2-dicyanomethyleneindane-1,3-dione (II) by ring-substituted anilines in acetonitrile is of nearly second order in the amine, is catalysed by pyridines, and shows a Hammett ρ value of –6·9 at 30°. A mechanism is suggested in which the zwitterion (III), formed initially by a reversible nucleophilic attack of the amine on (II), is reversibly deprotonated by a second amine molecule, followed by an anilinium ion-assisted expulsion of the cyanide ion. NN-Dimethyl-, N-methyl-, 2,5-dimethoxy-, 2,6-dimethoxy-anilines give para-addition products with (II).