[Reactions between dialkylamine drugs, 2,3-dichloro-1,4-naphthoquinone and acetaldehyde]

Dialkylamine drugs desipramine, propanolol, pindolol, alprenolol and metoprolol 4a-e react with 2,3-dichloro-1,4-naphthoquinone (2) and acetaldehyde to give red coloured 2-dialkylamino-3-chloro-1,4-naphthoquinones 5a, b, d, e, blue coloured 2-dialkylamino-vinyl-3-chloro-1,4-naphtho-quinones 1a-e and bluish green coloured 2-dialkylamino-butadienyl-3-chloro-1,4-naphthoquinones 6b-e. The colour products are isolated by column chromatography.