Regioselective dearomative hydroboration of N-heteroarenes provides direct access to partially saturated azacycles of high synthetic value. Herein, we report the highly 1,2-selective hydroboration of pyridines and quinolines catalyzed by a well-defined PC NHC P-supported Mn(I)-hydride. In contrast to previously reported metal-ligand cooperative manganese systems, this strong-field Mn catalyst operates via a non-cooperative pathway and exhibits distinct regio-and chemoselectivity profiles. A range of substituted pyridines and fused heteroarenes undergo selective 1,2-dearomatization under mild conditions. Competitive kinetic isotope effect (KIE) experiments (k H /k D ≈ 1.4) suggest involvement of B-H cleavage in the turnover-limiting step, which is further discussed in this report.
Kamte et al. (Thu,) studied this question.