化学
钴
催化作用
药物化学
溴化物
哌啶
亲核细胞
配体(生物化学)
组合化学
亚胺
立体化学
有机化学
受体
生物化学
作者
L. Reginald Mills,Francesca DiMare,David Gygi,Heejun Lee,Eric M. Simmons,Junho Kim,Steven R. Wisniewski,Paul J. Chirik
标识
DOI:10.1002/anie.202313848
摘要
Abstract Evaluation of the relative rates of the cobalt‐catalyzed C(sp 2 )–C(sp 3 ) Suzuki–Miyaura cross‐coupling between the neopentylglycol ester of 4‐fluorophenylboronic acid and N ‐Boc‐4‐bromopiperidine established that smaller N ‐alkyl substituents on the phenoxyimine (FI) supporting ligand accelerated the overall rate of the reaction. This trend inspired the design of optimal cobalt catalysts with phenoxyoxazoline (FOx) and phenoxythiazoline (FTz) ligands. An air‐stable cobalt(II) precatalyst, (FTz)CoBr(py) 3 was synthesized and applied to the cross‐coupling of an indole‐5‐boronic ester nucleophile with a piperidine‐4‐bromide electrophile that is relevant to the synthesis of reported toll‐like receptor (TLR) 7/8 antagonist molecules including afimetoran. Addition of excess KOMe⋅B(O i Pr) 3 improved catalyst lifetime due to attenuation of alkoxide basicity that otherwise resulted in demetallation of the FI chelate. A first‐order dependence on the cobalt precatalyst and a saturation regime in nucleophile were observed, supporting turnover‐limiting transmetalation and the origin of the observed trends in N ‐imine substitution.
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