Chiral amine–imine ligands based on trans-2,5-disubstituted pyrrolidines and their application in the palladium-catalyzed allylic alkylation
作者:Hongfeng Chen、James A. Sweet、Kin-Chung Lam、Arnold L. Rheingold、Dominic V. McGrath
DOI:10.1016/j.tetasy.2009.07.010
日期:2009.7
moiety affords dramatic changes on the outcome of the stereochemistry. Evidencefrom various studies suggested that during the palladium-catalyzed allylic alkylation reaction, nucleophilicattack onto the 1,3-diphenylallyl moiety in the transition state occurs mainly trans to the pyridine ring of the less stable conformation of the palladiumcomplexes.
Development of Chiral Bis-hydrazone Ligands for the Enantioselective Cross-Coupling Reactions of Aryldimethylsilanolates
作者:Scott E. Denmark、Wen-Tau T. Chang、K. N. Houk、Peng Liu
DOI:10.1021/jo502388r
日期:2015.1.2
aryldimethylsilanolates and arylbromides result in biaryl products with the same configuration and similar enantioselectivities implying that reductive elimination is the stereodetermining step. The origin of stereoselectivity is rationalized through computational modeling of diarylpalldium(II) complex which occurs through a conrotatory motion for the two aryl groups undergoing C–C bondformation.
Catalyst compositions useful for the polymerization or oligomerization of olefins are disclosed. Certain of the catalyst compositions comprise N-pyrrolyl substituted nitrogen donors. Also disclosed are processes for the polymerization or oligomerization of olefins using the catalyst compositions.
Asymmetric hydrogenation of diaryl 1,4-diketones was achieved by using trans-RuCl2[(S)-BINAP)][(S)-Daipen] as the catalyst and the reaction gave rise to excellent enantio- and diastereoselectivities (up to >99% ee and de). This procedure provides a convenient and efficient synthetic method for chiral 1,4-diarylbutane-1,4-diols, which are important intermediates for a variety of chiralauxiliaries and
使用反式-RuCl 2 [( S )-BINAP)][( S )-Daipen] 作为催化剂实现了二芳基 1,4-二酮的不对称氢化,反应产生了优异的对映选择性和非对映选择性(高达 > 99% ee和de )。该方法为手性 1,4-二芳基丁烷-1,4-二醇提供了一种方便有效的合成方法,该方法是多种手性助剂和配体的重要中间体。