CuO@Fe2O3 catalyzed C1-alkynylation of tetrahydroisoquinolines (THIQs) via A3 coupling and its decarboxylative strategies

Abstract

C1-Alkynylation of tetrahydroisoquinoline (THIQ) was achieved via the A3 coupling strategy from the reaction of THIQ as a secondary amine, aldehydes and alkynes using the CuO@Fe₂O₃ nanocatalyst under green reaction conditions. The wide scope of the present method was studied using various aliphatic/aromatic aldehydes and alkynes to afford the corresponding C1-alkynylated products in quantitative yields. Moreover, the present catalytic system was found to be versatile for the decarboxylative A3 coupling strategy with improved progress of reactions by replacing the alkynes with phenylpropiolic acid under optimized conditions. The present catalytic system was found to be robust, magnetically recoverable and recyclable 5 times without significant loss in its activity, offering a low E-factor and high atom economy (AE).