Hydroboration of Unsaturated Phosphonic Esters:  Synthesis of Boronophosphonates and Trisubstituted Vinylphosphonates

Hydroboration of vinyl phosphonates with pinacolborane (PBH) proceeds to give phosphonoboronates, 2. Surprisingly, such compounds have not been reported before. The reaction works well with terminal alkenylphosphonates. Internal alkenylphosphonates give complex mixtures. Hydroboration/Suzuki coupling of alkynylphosphonates, with PBH, in a one-pot procedure gives trisubstituted vinylphosphonates in good overall yields and provides a new synthesis of these compounds.