Quick Access to Protoberberine and Tetrahydroprotoberberine Derivatives/Analogues with One-Pot Sequential Isochromenylium-Mediated Annulation

J Org Chem. 2024 Sep 6;89(17):12853-12857. doi: 10.1021/acs.joc.4c01540. Epub 2024 Aug 27.

Abstract

A one-pot access to the protoberberine and tetrahydroprotoberberine scaffold has been developed from easily available primary amine-functionalized o-alkynylbenzaldehydes. The core skeleton of protoberberine was afforded via in situ generation of isochromenylium by Ag(I) catalysis, subsequent cyclization to isoquinolinium, and final hydride reduction by a continuous operation procedure. The newly developed step-economic protocol shows excellent regio- and stereoselectivity and is capable of achieving those previously unavailable derivatives/analogues with electron-deficient substituents, providing a robust tool for medicinal investigations of protoberberines and derivatives.