Reactions of amines and formaldehyde/aryl aldehydes in combination or in isolation, with 1-(2-hydroxyphenyl)-1,3-butanedione

Reaction of 1-(2-hydroxyphenyl)-1,3-butanedione 1 with aliphatic primary amines gives imines through the attack of NH 2 at the CO adjacent to the benzene ring. The dione 1 reacts with aryl aldehydes in the presence of a secondary amine to give chalcones while it reacts with Schiff bases of aryl aldehydes and amines to yield imines. It affords 2-methylchromone when boiled in ethanol with a secondary amine. Its reaction with formaldehyde yields a mixture of 3-hydroxymethyl-2-methylchromone and 3-acetylbischromanylmethane. 1 reacts with secondary amines and formaldehyde to give 3-aminomethyl-2-methyl-chromones.