Nucleophilic attacks on carbon–carbon double bonds. Part XX. Reaction of active methylene compounds with electrophilic olefins. Formation of substituted 2-amino-4-cyano-4H-pyrans

Abstract

Reactions of active methylene compounds with several electrophilic olefins are initiated by a nucleophilic attack on the double bond and the following reaction types have been observed. (a) Base-catalysed reaction of malononitrile with 1,1-dinitro-2,2-diphenylethylene gives ‘diphenylmethylene transfer’ forming 1,1-dicyano-2,2-diphenylethylene. (b) Addition of acetylacetone to tetracyanoethylene (IX) and to diethyl 2,3-dicyanofurmarate (X) or of dimedone to (X) gives the non-cyclic Michael adducts 3-(1,1,2,2-tetracyanoethyl)pentane-2,4-dione (XIII), diethyl 2,3-dicyano-2-diacetylmethylsuccinate (XX), and diethyl 2,3-dicyano-2-(4,4-dimethyl-2,6-dioxocyclohexyl)succinate (XXII), respectively. (c) Non-catalysed addition of several active methylene compounds to (IX) or to (X) gives substituted 2-amino-4-cyano-4H-pyrans. These are probably formed by cyclisation of the open adducts, since a non-catalysed cyclisation of (XIII) and of (XXII) gives the 4H-pyran derivatives. (d) Reaction of anthrone with (IX) and (X) gives the 10-substituted anthrone Michael adducts. Addition of bases to the adduct from (IX) gives bianthrone and products derived from (IX), apparently via decomposition of the adduct to anthrone and (IX).