Decarboxylative Cross-Dehydrogenative Coupling of Tetrahydroisoquinoline and Alkynoic Acids Using Recyclable Carbon Nanotube Supported Copper/Nickel Oxide Catalysts

Abstract

We present a decarboxylative cross-dehydrogenative coupling (CDC) reaction between tetrahydroisoquinoline (THIQ) derivatives and alkynoic acids using a carbon nanotube-supported copper/nickel oxide (CNT-CuO/Ni) catalyst. This catalyst leverages the catalytic properties of copper and magnetic recoverability of nickel to facilitate efficient carbon─carbon bond formation under mild conditions while allowing for easy separation and reuse. Under optimized conditions, the reaction produced various 1-alkynyl-2-aryl-1,2,3,4-tetrahydroisoquinoline derivatives in good yields. The CNT-CuO/Ni catalyst exhibited significant reusability, retaining high catalytic performance through 12 reaction cycles. Competition experiments revealed that the electronic properties of substituents on the phenyl propiolic acid and THIQ aryl groups had a minimal effect on the reaction outcome. This study underscores the potential of CNT-CuO/Ni as a recyclable catalyst for sustainable organic synthesis in decarboxylative CDC reactions.