Cobalt-Catalyzed Regiodivergent Ring-Opening Dihydroboration of Arylidenecyclopropanes to Access Skipped Diboronates.

Ligand-controlled regiodivergent cobalt-catalyzed ring-opening dihydroboration of arylidenecyclopropanes is developed to access synthetically versatile skipped diboronates with catalysts generated in situ from Co(acac) and dpephos or xantphos. A variety of arylidenecyclopropanes reacted with pinacolborane (HBpin) to form the corresponding 1,3- or 1,4-diboronates in high isolated yields and with high regioselectivity. Skipped diboronate products from these reactions can undergo various transformations to allow selective installation of two different functional groups along alkyl chains. Mechanistic studies suggest that these reactions combine cobalt-catalyzed ring-opening hydroboration of arylidenecyclopropanes and hydroboration of homoallylic or allylic boronate intermediates.