开发了新的非手性3,3',5,5'-四取代-2,2',6,6'-四羟基联苯配体4。配位体的轴向手性可以通过2,2',6,6'-四羟基与(R)-BINOL-Ti(O i Pr)2的螯合来诱导,以形成轴向手性双金属钛催化剂9。与(R)-BINOL-Ti(O i Pr)2催化剂相比,该新型催化剂9对于甲基苯乙烯和乙醛酸乙酯的羰基-烯反应显示出优异的活性和对映选择性。3,3',5,5'-四取代基对对映选择性和收率均显示出显着影响。与9d以3,3′,5,5′-四甲基-2,2′,6,6′-四羟基联苯4d为催化剂制备得到的最佳结果,ee高达97.6%,产率为99%。另外,双金属催化剂9也显示出比相应的单金属催化剂更好的催化能力。
biphenyl phosphoramidites bearing a D2-symmetric biphenyl backbone was prepared and applied as chiral ligands in the copper-catalyzedallylicalkylation with Grignard reagent. The alkylation products were obtained in quantitative yields with high regioselectivities up to 94:6 of SN2′/SN2 ratio and enantiomeric excesses up to 91.1% for SN2′ products. The unique D2-symmetric backbone ligands have the
制备了一类新型的具有D 2-对称联苯骨架的对映体双桥联苯二亚磷酰胺,并将其用作手性配体,用格氏试剂在铜催化的烯丙基烷基化反应中使用。烷基化产物以定量产率获得,具有高达S N 2'/ S N 2之比的94:6的高区域选择性,并且对于S N 2'产物,对映体过量高达91.1%。独特的D 2-对称主链配体的优点是易于制备,并且其关键中间体可以从不希望的异构体中充分利用。
New tetraphosphite ligands for regioselective linear hydroformylation of terminal and internal olefins
tetraphosphite ligands L1–L5 and applied them to the rhodium-catalyzed hydroformylation of terminal and internal olefins. High catalytic reactivities and excellent regioselectivities for linear aldehydes were obtained in the rhodium-catalyzed hydroformylation of simple olefins (l/b ratio up to 90, 98.9% linear selectivity, 99.2% conversion) using the tetraphosphite ligand L2. And the tetraphosphite ligand L2 also
A series of new pyrrole-based tetraphosphorus ligands were synthesized and used for Rh-catalyzed isomerization-hydroformylation of internal olefins. It was found that the substituents at the 3,3',5,5'-positions of the biphenyl greatly effected the linear selectivity, and the alkyl-substituted tetraphosphorus ligands gave the best results (for 2-octene, n: i up to 207, for 2-hexene, n: i up to 362)
Atropos phosphoramidites with the D-2-symmetric biphenyl backbone were diastereoselectively prepared with ease from achiral tetrahydroxy biphenyls. This type of ligands is proved to be highly efficient in the Cu-catalyzed conjugate additions of diethylzinc to alpha,beta-unsaturated ketones and nitroalkenes. The unique D-2-symmetric backbone endows the ligands with an excellent chiral environment. (C) 2010 Elsevier Ltd. All rights reserved.