Structural tuning enables piezochromic and photochemical properties in N-aryl-ß-enaminones.

An efficient synthesis of N-aryl-ß-enaminones via Et3N-mediated, one-pot three-component reaction of 4-hydroxycoumarin/dimedone, ß-nitrostyrene/2-(2-nitrovinyl)thiophene, and arylamine in toluene under refluxed conditions is herein presented. Some prepared compounds were found to exhibit piezochromic properties. The XRD and SEM measurements of the piezochromic compound showed substantial crystal packing and morphology changes before and after grinding. Further, one prepared compound was found to be light-sensitive and can be converted to a furo[3,2-b]pyridin-2(4H)-one derivative upon UV irradiation. A plausible mechanism for this photochemical reaction was proposed.

Multicomponent synthesis of pyrano[2,3-c]coumarins.

A base-catalyzed, pseudo-four-component reaction of 4-hydroxycoumarin, two molecules of acetone, and amine towards the synthesis of pyrano[2,3-c]coumarins is reported. The mechanism of this multicomponent reaction is proposed. The reaction is further extended to the preparation of coumarin-substituted pyrano[2,3-c]coumarins by a base-catalyzed, pseudo four-component reaction of two molecules of 4-hydroxycoumarin and two molecules of acetone.