Borate-Enabled Phenoxyimine Cobalt-Catalyzed C(sp2)–C(sp3) SuzukiMiyaura Cross-Coupling with (Hetero)Arylboronic Acid Nucleophiles

Le résumé fourni par la source

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.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.