School of Chemistry, University of Bristol, Cantocks Close, Bristol, UK BS8 1TS.
Dalton Trans. 2011 Sep 21;40(35):9034-41. doi: 10.1039/c1dt10356c. Epub 2011 Aug 5.
A range of chiral resorcinol bis(phosphite) and phosphite-phosphinite ligands were produced and their propensity to form palladium PCP-pincer complexes examined. The ease of base-assisted C-H palladation of the ligands falls in the order bis(phosphinite) > phosphite-phosphinite > bis(phosphite). The catalytic activity of the complexes in the asymmetric allylation of benzaldehyde with allyl tributyltin was examined and it was found that, contrary to expectations, ligands with 3,3'-disubstituted BINOL residues show poorer activity and stereoselectivity than unsubstituted BINOL analogues. In addition the order of activity of the pincer complexes was established as bis(phosphite) > phosphite-phosphinite > bis(phosphinite). Crystal structures of representative examples of a 3,3'-disubstituted BINOL, mono- and bis(phosphite) ligands based on 2,4-di-tert-butyl resorcinol and Pd complexes of two of the chiral complexes are presented.
一系列手性间苯二酚双（膦酸酯）和膦酸酯-亚磷酸酯配体被合成出来，并对它们形成钯 PCP-钳形配合物的倾向进行了研究。配体的碱辅助 C-H 钯化的容易程度顺序为双（亚磷酸酯）>膦酸酯-亚磷酸酯>双（膦酸酯）。研究了配合物在苯甲醛与烯丙基三丁基锡的不对称烯丙基化反应中的催化活性，结果发现，与预期相反，具有 3,3'-取代 BINOL 残基的配体的活性和对映选择性比未取代的 BINOL 类似物差。此外，确定了 pincer 配合物的活性顺序为双（膦酸酯）>膦酸酯-亚磷酸酯>双（亚磷酸酯）。介绍了 3,3'-取代 BINOL、基于 2,4-二叔丁基间苯二酚的单膦酸酯和双膦酸酯配体以及两种手性配合物的钯配合物的代表性实例的晶体结构。
