Palladium-Catalyzed Diastereoselective and Enantioselective Allylic Alkylations of Ketone Enolates
作者:Manfred Braun、Thorsten Meier、Frank Laicher、Panos Meletis、Mesut Fidan
DOI:10.1002/adsc.200700409
日期:2008.1.25
the lithium enolates, the presence of lithium chloride is also crucial to reactivity and stereoselectivity. The stereochemical outcome of the allylic alkylation of cyclohexanone and acetophenone has been investigated by the palladium-catalyzed reaction of their lithium enolates with the cis/trans isomeric alkenes (Z)-18 and (E)-19. It turns out that the preformed, non-stabilized enolates attack π-allyl-palladium
环己酮的锂和镁的烯醇化物在温和的条件下经历钯催化的烯丙基烷基化反应。当二苯基和二甲基取代的烯丙基底物1a和1b与环己酮或乙基异丁基酮反应时,观察到非对映选择性和对映选择性。环己酮,环戊酮和α-四氢萘酮的烯醇锂导致烷基化产物12 – 14以对映选择性的方式。轴向手性联苯基和联萘基双膦提供高对映选择性和/或非对映选择性。就烯醇锂而言,氯化锂的存在对反应性和立体选择性也至关重要。环己酮和苯乙酮的烯丙基烷基化的立体化学结果已通过钯催化的其烯醇锂与顺式/反式异构烯烃(Z)-18和(E)-19的反应进行了研究。事实证明,预先形成的不稳定的烯醇盐会攻击原位生成的π-烯丙基-钯配合物 从与贵金属相反的表面开始,因此遵循了柔软,稳定的碳负离子的立体化学路径。