Complementary pairing of o-quinone methides with 3-(N,N-diethylamino)acrolein – synthesis of 1H-benzo[f]chromene-2-carbaldehydes

A series of 1H-benzo[f]chromene-2-carbaldehydes was obtained from naphthol Mannich bases and 3-(N,N-diethylamino)acrolein via a cascade reaction comprising [4+2] cycloaddition of generated in situ 1,2-naphthoquinone-2-methides and a push-pull β-enaminoaldehyde with consecutive elimination of diethylamine.