Oxidation-Induced beta-Selective C-H Bond Functionalization: Thiolation and Selenation of N-Heterocycles

摘要

Site-selective intermolecular C-H bond functionalization is of central importance to synthetic chemistry. In particular, direct beta-functionalization of N-heterocycles still remains a great challenge. Herein, we develop a strategy for oxidation-induced thiolation and selenation at the beta-position of piperidine derivatives and 1,2,3,4-tetrahydroisoquinoline via C-H bond functionalization. Various 4-sulfenylisoquinolines, 3-sulfenylpyridines, and 4-selenylisoquinolines can be obtained by using O-2 as the only oxidant. Notably, neither a directing group nor a metal catalyst is necessary in this transformation. The preliminary mechanistic studies revealed that the oxidation and rearrangement pathway were key steps in this transformation, which provides a meaningful strategy for controlling site selectivity in the beta-functionalization of N-heterocycles.