具有特意设计的膦配体的离散钯 (II) 配合物可促进细胞裂解物中的去炔丙基化和去烯丙基化反应。这些络合物的性能优于其他钯源,后者显然在这种不利的络合物介质中迅速失活。这种反应性和稳定性之间的良好平衡允许在活哺乳动物细胞中使用这些离散的膦钯配合物,从而它们可以介导类似的转化。在钯的配位层中存在膦配体还提供了靶向基团的引入,例如疏水性磷部分,这有助于复合物在线粒体中的积累。
Development, Synthetic Scope, and Mechanistic Studies of the Palladium-Catalyzed Cycloisomerization of Functionalized 1,6-Dienes in the Presence of Silane
作者:Philip Kisanga、Ross A. Widenhoefer
DOI:10.1021/ja001730+
日期:2000.10.1
A 1:1 mixture of the pi-allyl palladium complex (eta (3)-C3H5)Pd(CI)PCy3 Cia) and NaB[3,5-C6H3(CF3)(2)](4) in the presence of HSiEt3 catalyzed the cycloisomerization of diethyl diallylmalonate (2b) to form 4,4-dicarbomethoxy 1,2-dimethylcyclopentane (3b) in 98% yield with 98% isomeric purity. The procedure tolerated a range of functionality including esters, ketones, sulfones, protected alcohols, and substitution at the allylic and terminal olefinic carbon atoms. Cycloisomerization of 2b obeyed zero-order kinetics to >3 half-lives with initial formation of 1,1-dicarboethoxy-4-methyl-3-methylenecyclopentane (4b), followed by secondary isomerization to 3b. Deuterium labeling studies revealed that the conversion of 2b to 4b was accompanied by significant H/D exchange, consistent with an addition/elimination pathway coupled with facile H/D exchange of the Pd-H(D) intermediates with free silane.