Silylative Reductive Amination of α,β‐Unsaturated Aldehydes: A Convenient Synthetic Route to β‐Silylated Secondary Amines

Described here is a reductive amination/hydrosilylation cascade of α,β‐unsaturated aldehydes mediated by a Lewis acidic borane catalyst. The present reaction system provides an one‐pot synthetic route towards β‐silylated secondary amines that have not been accessible by other previous catalysis. Comparative 1 H NMR studies on the silylative reduction of enimines revealed that steric bulkiness of primary amine reactants strongly affects both catalytic efficiency and regioselectivity. This strategy was applicable to a broad range of substrates and amenable to one‐pot gram‐scale synthesis. Moreover, a diastereoselective introduction of the β‐silyl group was also found to be feasible (d.r. up to 71:29).