Synthesis of\nα‑Boryl-α-Substituted\nAllylboronates from Propyne

A novel\nmethod for the two-step synthesis of α-boryl-α-substituted\nallylboronates from propyne is described. These allylboronates are\nprepared by the Co-catalyzed 1,1-diboration reaction of propyne with\nB<sub>2</sub>pin<sub>2</sub>, followed by the base-mediated alkylation\nreaction of 1,1-di(boryl)propene at the α-position. Computational\nstudies revealed the origins of observed reactivity and selectivity\nin the base-mediated alkylation reaction. The resulting α-boryl-α-methyl-allylboronate\nis applied to the allylation of aldehydes, which gives homoallylic\nalcohols with a trisubstituted alkene moiety.