Deconvoluting the Memory Effect in Pd-Catalyzed Allylic Alkylation: Effect of Leaving Group and Added Chloride
作者:Peter Fristrup、Thomas Jensen、Jakob Hoppe、Per-Ola Norrby
DOI:10.1002/chem.200600152
日期:2006.7.5
syn- and anti-[Pd(eta3-allyl)] complexes. Addition of chloride triggers a true memory effect, in which the allylic terminus originally bearing the leaving group has a higher reactivity. The latter effect, termed regioretention, can be rationalized by ionization from a palladium complex bearing a chloride ion, forming an unsymmetrically substituted [Pd(eta3-allyl)] complex. DFT calculations verify that
对Tsuji-Trost反应中产物分布的分析表明,已报道的“记忆效应”的几种情况可归因于最初形成的顺式和反式[Pd(eta3-烯丙基)]配合物的缓慢互变。氯化物的添加触发了真正的记忆效应,其中最初带有离去基团的烯丙基末端具有更高的反应性。后者的作用称为区域保留,可以通过从带有氯离子的钯络合物中进行电离来合理化,从而形成不对称取代的[Pd(eta3-烯丙基)]络合物。DFT计算证实,在初始电离和随后的亲核攻击中,膦配体的反式位置均具有更高的反应性。