A facile synthesis of novel indole-based chalcones (E)-1-(2-chloro-1-methyl-1H-indol-3-yl)-3-arylprop-2-en-1-ones

A facile and general synthesis of 23 novel indole-based chalcones, (E)-1-(2-chloro-1-methyl-1H-indol-3-yl)-3-arylprop-2-en-1-ones, has been achieved in good yields of 71-89% by the Claisen-Schmidt condensation reaction of 3-acetyl-2-chloro-N-methylindole with variously substituted araldehydes using 1,4-dioxane as solvent in the presence of 5% aq. KOH. A similar reaction using furan-2- or thiophene-2-carbaldehyde gave analogous products in good yield, but an unexpected aldol reaction occurred with 2-nitrobenzaldehyde and the stable aldol product was isolated as the major product in a good yield of 73%.