Copper-Catalyzed Electrophilic Amination of gem-Diborylalkanes with Hydroxylamines Providing α-Aminoboronic Acid Derivatives

A copper-catalyzed electrophilic amination of gem-diborylalkanes with hydroxylamines has been developed. The key to its success is the use of the Me3Si-modified 1,2-bis(diphenylphosphino)benzene ligand. Additionally, the reactivity of neopentylglycol derivatives compared to that of commonly used pinacol-derived ones is found to be higher, particularly in the case of relatively sterically congested substrates. The copper catalysis presented here enables the first successful catalytic carbon-heteroatom bond forming reaction of gem-diborylalkanes to form the corresponding alpha-aminoboronic acid derivatives, which are of great interest in medicinal and pharmaceutical chemistry.