Anti-Markovnikov hydrosilylation and Markovnikov hydroboration of alkenes by a phenanthroline-based tridentate manganese catalyst

Abstract

The divergent regioselective hydrosilylation and hydroboration of alkenes by a single manganese catalyst are disclosed. Using the Mn catalyst bearing the tridentate phenanthroline scaffold, alkenes were found to undergo anti-Markovnikov hydrosilylation, while the hydroboration of alkenes afforded Markovnikov's products. Both the hydrosilylation and the hydroboration of alkenes proceed under mild conditions (room temperature, neat conditions) with low catalyst loadings (1 mol%) using NaOtBu (3 mol%) as an activator. The reactions are atom-economical, exhibiting a broad substrate scope (46 examples), and excellent functional group tolerance (including aromatic and aliphatic alkenes). Importantly, the presented catalytic systems are suitable for various synthetic applications, and could be extended to the synthesis of bioactive molecules. Mechanistic studies supported that the Mn-H species are crucially important for the catalytic process.