Aluminum Hydride Catalyzed Hydroboration of Alkynes

Abstract An aluminum‐catalyzed hydroboration of alkynes using either the commercially available aluminum hydride DIBAL‐H or bench‐stable Et 3 Al⋅DABCO as the catalyst and H‐Bpin as both the boron reagent and stoichiometric hydride source has been developed. Mechanistic studies revealed a unique mode of reactivity in which the reaction is proposed to proceed through hydroalumination and σ‐bond metathesis between the resultant alkenyl aluminum species and HBpin, which acts to drive turnover of the catalytic cycle.