作者:Paolo Larini、Christos E. Kefalidis、Rodolphe Jazzar、Alice Renaudat、Eric Clot、Olivier Baudoin
DOI:10.1002/chem.201103153
日期:2012.2.13
palladium‐catalyzed β‐arylation of ester enolates with aryl bromides was studied both experimentally and computationally. First, the effect of the ligand on the selectivity of the α/β‐arylation reactions of ortho‐ and meta‐fluorobromobenzene was described. Selective β‐arylation was observed for the reaction of o‐fluorobromobenzene with a range of biarylphosphine ligands, whereas α‐arylation was predominantly
实验和计算研究了钯催化的酯烯醇盐与芳基溴化物的β-芳基化反应。首先,描述了配体对邻-和间-氟溴代苯的α/β芳基化反应选择性的影响。观察到的反应选择性β的芳基化ö -fluorobromobenzene与一系列biarylphosphine配体,而α芳基化物主要与观察米除DavePhos以外的所有配体均使用了氟代溴苯,后者可制得约1:1的α-/β芳基化产物混合物。接下来,以DavePhos为配体研究了芳基溴化物反应物的取代方式的影响。我们表明,电子因素在α/β芳基化选择性中起主要作用,而吸电子取代基则有利于β芳基化。动能和氘标记实验表明,β-芳基化与DavePhos作为配体的限速步骤是钯-烯醇化物-到高烯醇化物异构化,其中发生由β H-消除,烯烃旋转和烯烃插入顺序。分离出二聚氧化加成络合物,并证明其具有催化能力,并对其结构进行了表征。DFT计算描述了α和β芳基化的常见机制。以DavePho