Chiral amine–imine ligands based on trans-2,5-disubstituted pyrrolidines and their application in the palladium-catalyzed allylic alkylation
作者:Hongfeng Chen、James A. Sweet、Kin-Chung Lam、Arnold L. Rheingold、Dominic V. McGrath
DOI:10.1016/j.tetasy.2009.07.010
日期:2009.7
moiety affords dramatic changes on the outcome of the stereochemistry. Evidence from various studies suggested that during the palladium-catalyzed allylic alkylation reaction, nucleophilic attack onto the 1,3-diphenylallyl moiety in the transition state occurs mainly trans to the pyridine ring of the less stable conformation of the palladium complexes.
已经制备了一系列基于反式-2,5-二取代的吡咯烷和吡啶部分的胺-亚胺二齿配体。这些配体在rac-(E的钯催化的烯丙基烷基化反应中的用途报道了-1,3-二苯基丙-2-烯基乙酸酯。结果表明这些配体是反应的良好催化剂前体。配体的吡啶环上的电子修饰对反应的对映选择性没有明显影响,但对反应速率的影响很大,而吡啶或吡咯烷部分上的结构修饰对立体化学的结果产生了显着变化。从各种研究的证据表明,在钯催化的烯丙基烷基化反应过程中,亲核进攻于在过渡状态下的1,3- diphenylallyl部分主要发生反式与钯配合物的较稳定的构象的吡啶环。