Synthesis of potentially photoactivatable cournarin derivatives via a 1,3-dipolar cycloaddition

A copper (I)-catalyzed 1,3-dipolar cycloaddition reaction was used to prepare a series of mono and disubstituted 1,2,3-triazolyl-coumarins using a 1,3-cycloaddition ("Click Chemistry"). Starting coumarins were synthesized using classical or modified Pechmann's reaction. The propargyl group was introduced as either propargylether or as a propargylamide. Azides were prepared in a three steps procedure. Cycloaddition products, containing a coumarin and a photoactivatable moiety, were obtained in good yields.