Frontiers in Copper-promoted C1-functionalization of Tetrahydroisoquinoline Using Cross-dehydrogenative Coupling

Abstract

Abstract: The site-selective diversification of molecules is a pertinent unresolved issue within the area of organic chemistry. The functionalization of Csp3-H has changed the landscape of synthetic chemistry by enabling effective direct coupling of compounds and reducing chemical waste by avoiding the usage of pre-functionalized compounds. The 1,2,3,4- tetrahydroisoquinoline (THIQ), a molecule with potential bioactivity, has a stereoselective center at the C1 position. However, there is still a fundamental problem with the C1-functionalization of THIQs. To address this, transition metal-catalyzed cross-dehydrogenative coupling (CDC) has evolved into an essential tool because such reactions can be carried out with enantio-, regio-, and stereoselectivity. In particular, copper-promoted CDC reactions have undoubtedly made substantial progress in THIQ chemistry as a selective protocol. The α-Csp3-H bond adjacent to the Natom of THIQs is activated using copper catalysts, followed by dehydrogenative coupling with various alkynyl, alkane, and alkene groups to form the Csp-Csp3, Csp3-Csp3, and Csp3-Csp2 bonds and produce optically active C1-substituted THIQs. The A3 coupling strategies also produce the endo-yne-THIQs with higher selectivity. This critical discussion highlights all recent advancements (between 2010 and 2022) in CDC reactions to THIQs with the substrate scope and plausible mechanistic routes. This study may be extremely useful to scientists and researchers working on copper-promoted CDC.