Oxidative Rearomatization of Tetrahydroisoquinolines Promoted by Pyridine-<i>N</i>-oxide

Isoquinolines are ubiquitous arenes found in many biologically useful molecules. While direct substitution at the heterocyclic ring is uncommon, reductive functionalization to form tetrahydroisoquinolines (THIQs) is straightforward. Herein, we describe a facile method for producing C4-functionalized isoquinolines from a readily available parent THIQ. This high-temperature transformation utilizes pyridine-<i>N</i>-oxide as an oxidant generating only volatile side products and is functional-group-tolerant.