Fristrup Peter, Jensen Thomas, Hoppe Jakob, Norrby Per-Ola
Department of Chemistry, Technical University of Denmark, Building 201, Kemitorvet, 2800 Kgs. Lyngby, Denmark.
Chemistry. 2006 Jul 5;12(20):5352-60. doi: 10.1002/chem.200600152.
An analysis of product distributions in the Tsuji-Trost reaction indicates that several instances of reported "memory effects" can be attributed to slow interconversion of the initially formed 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 the position trans to the phosphine ligand is more reactive both in the initial ionization and in the subsequent nucleophilic attack.
对辻-特罗斯特反应中产物分布的分析表明，所报道的几个“记忆效应”实例可归因于最初形成的顺式和反式-[钯（η³-烯丙基）]配合物之间的缓慢相互转化。加入氯离子会引发真正的记忆效应，其中最初带有离去基团的烯丙基末端具有更高的反应活性。后一种效应，称为区域保留，可以通过从带有氯离子的钯配合物中电离来解释，形成不对称取代的[钯（η³-烯丙基）]配合物。密度泛函理论计算证实，在初始电离和随后的亲核攻击中，与膦配体反位的位置反应性更高。
