Abstract
<jats:p>The C(sp2)–C(sp3) Suzuki–Miyaura cross-coupling of arylboronic acid nucleophiles with alkyl halide electrophiles using phenoxy(imine) cobalt(II) precatalysts is described. The one-pot method involved generation of KOMe•B(OiPr)3 as a singlecomponent base–borate adduct to facilitate transmetalation of the nucleophile onto the cobalt. The optimized reaction conditions employed 2.5 mol% of (MeFI)cobalt(II) bromide precatalyst and were conducted at 40 ºC, a lower barrier for product formation than previously reported cobalt-catalyzed methods. Monitoring the reaction of KOMe•B(OiPr)3 with 4-fluorophenylboronic acid by 1H and 19F NMR spectroscopies established formation of a mixture of several activated potassium arylboronate species by transesterification that were more reactive towards transmetalation to the (MeFI)cobalt(II) center than neutral boronates. Evaluation of reaction time courses with 4-fluorophenylboronic acid and KOMe•B(OiPr)3 established increased rates of product formation and diminished rates of protodeboronation when compared to cross-coupling of 4-fluorophenyl–B(neo) activated by KOMe, providing insight into cross-coupling viability in the presence of acidic protons inherently present in (hetero)arylboronic acid reagents.</jats:p>