Aluminum Amidinates: Insights into Alkyne Hydroboration

The mechanism of the aluminum-mediated hydroboration terminal alkynes was investigated using a series novel aluminum amidinate hydride and alkyl complexes bearing symmetric asymmetric ligands. new were fully characterized found to facilitate formation (E)-vinylboronate product, with rates orders reaction linked complex size stability. Kinetic analysis stoichiometric reactions used elucidate mechanism, which we propose proceed via initial an Al-borane adduct. Additionally, most unstable promote decomposition pinacolborane substrate borane (BH3), can then catalyze reaction. This is in contrast previously reported hydride-catalyzed reactions, are proposed acetylide, or by hydroalumination form vinylboronate ester as first step catalytic cycle.