Click chemistry approach for the regioselective synthesis of iso-indoline-1,3-dione-linked 1,4 and 1,5 coumarinyl 1,2,3-triazoles and their photophysical properties

Copper-catalyzed reaction of N-propargyl isoindoline-1,3-dione and 4-azidomethyl coumarins / 4-azidomethyl-1-aza coumarins under click chemistry conditions afforded 1,4-disubstituted 1,2,3-triazoles, whereas ruthenium catalysis yielded isomeric 1,5-disubstituted 1,2,3-triazoles. The two regioisomers have been distinguished by NOE studies. UV absorption for a given pair of isomers exhibited similar trend, whereas fluorescence measurements showed considerable differences. Photo physical studies on the interaction of azides with copper and ruthenium have also been performed.