Reactions of β-dimethylaminoacrolein aminal and 3-dimethylamino-1,1,3-tri-methoxypropane with alkylidenemalononitriles

The reaction of alkylidenemalononitriles with β-dimethylaminoacrolein aminal unexpectedly results in (3-dimethylaminopropen-1-ylidene)malononitrile, whereas the reaction of 1-dimethylamino-1,3,3-trimethoxypropane gives unknown ω,ω-bis(3-dimethylaminopropen-2-ylidene)alkylidenemalononitriles.