Copper-Catalyzed Oxidative Acetalization of Boronic Esters: An Umpolung Strategy for Cyclic Acetal Synthesis.

A protocol for the acetalization of boronic esters is described. The reaction is catalyzed by copper, and the conditions proved to be mild and were amenable to a variety of functional groups. We expanded the Chan-Lam coupling to include C(sp) nucleophiles and converted them into corresponding acetals. This method allows for the orthogonal acetalization of substrates with reactive, acid-sensitive functional groups.