Catalytic Conversion of N‑Heteroaromatics to Functionalized Arylamines by Merging Hydrogen Transfer and Selective Coupling

To date, although
tremendous advances have been made in N-heteroaryl
C–H functionalization, there remain significant unmet challenges
in the deconstruction of extensively applied but poorly reactive N-heteroaromatics
to useful frameworks. Here, by a strategy merging hydrogen transfer
and selective coupling, we present a ruthenium-catalyzed deconstruction
of N-heteroaromatics to functionalized arylamines with 2-aminoaryl
methanols. The reaction is achieved via sequential functionalization
of the β and α sites of the initially formed N-heteroarenium
salts followed by a C–N cleavage, which proceeds with the striking
features of broad substrate scope, excellent functional group tolerance,
high chemoselectivity and atom efficiency, and suitability for a streamlined
synthesis of some biomedical molecules. The strategy utilized will
pave the way for further development of catalytic transformations
of inert organo systems to functional frameworks.

迄今为止，尽管N-杂芳基C-H官能化（N-heteroaryl C–H functionalization）领域已取得长足进展，但将应用广泛却反应活性较低的N-杂芳烃（N-heteroaromatics）解构为高价值功能骨架的研究仍存在诸多亟待攻克的重大挑战。本研究通过整合氢转移（hydrogen transfer）与选择性偶联（selective coupling）的策略，报道了一种以2-氨基芳基甲醇（2-aminoaryl methanols）为偶联底物，经钌催化（ruthenium-catalyzed）将N-杂芳烃解构为官能化芳基胺的方法。该反应通过先对初始生成的N-杂芳鎓盐（N-heteroarenium salts）的β位与α位进行连续官能化，再发生C-N键裂解（C–N cleavage）得以实现，其具有底物适用范围广、官能团耐受性优异、化学选择性与原子经济性高，且可用于部分生物医学分子的简洁合成等突出特点。该策略将为惰性有机体系催化转化为功能化骨架的后续研究铺平道路。