A new strategy has been established for the kineticresolution of racemic allylic alcohols through a palladium/sulfonyl‐hydrazide‐catalyzed asymmetric OH‐substitution under mild conditions. In the presence of 1 mol % [Pd(allyl)Cl]2, 4 mol % (S)‐SegPhos, and 10 mol % 2,5‐dichlorobenzenesulfonyl hydrazide, a range of racemic allylic alcohols were smoothly resolved with selectivity factors of more than
enabled nickel‐catalyzed hydroalkenylation of aldehydes and styrenederivatives has been developed. The Brønsted acid acts as a proton shuttle to transfer a proton from the alkene to the aldehyde, thereby leading to an economical and byproduct‐free coupling. A series of synthetically useful allylic alcohols were obtained through one‐step reactions from readily available styrenederivatives and aliphatic
Catalytic Highly Enantioselective Alkylation of Aldehydes with Deactivated Grignard Reagents and Synthesis of Bioactive Intermediate Secondary Arylpropanols
作者:Yi Liu、Chao-Shan Da、Sheng-Li Yu、Xiao-Gang Yin、Jun-Rui Wang、Xin-Yuan Fan、Wei-Ping Li、Rui Wang
DOI:10.1021/jo101351t
日期:2010.10.15
of the high reactivity of Grignard reagents, a direct, highly enantioselective Grignard reaction with aldehydes has rarely been disclosed. In this report, Grignard reagents were introduced with bis[2-(N,N′-dimethylamino)ethyl] ether (BDMAEE) to effectively deactivate their reactivity; thus, a highly enantioselective alkylation of aldehydes with Grignard reagents resulted from catalysis by (S)-BINOL-Ti(OiPr)2
由于格氏试剂的高反应性,很少公开与醛类直接,高度对映选择性的格氏试剂反应。在该报告中,格氏试剂与双[2-(N,N'-二甲基氨基)乙基]醚(BDMAEE)一起引入,以有效地使其活性失活。因此,由(S)-BINOL-Ti(O i Pr)2催化导致格氏试剂对醛的高度对映选择性烷基化。认为BDMAEE螯合了RMgBr的Schlenk平衡的原位生成的盐MgBr 2和RMgBr与Ti(O i Pr)4的重金属化产生的Mg(O i Pr)Br的螯合作用。镁盐可以积极地促进不希望有的背景反应,生成外消旋体。该螯合作用无疑抑制了Mg盐的催化活性,抑制了不需要的背景反应,并且使得能够被(S)-BINOL-Ti(O i Pr)2催化的高对映选择性加成。因此,与以前的研究相比,没有除去Mg盐的副产物,使用了比RMgBr少的Ti(O i Pr)4,并且在该催化不对称反应中避免了极低的温度。各种烷基格氏试剂中的不对称
Stereospecific Allyl-Aryl Coupling Catalyzed by<i>in situ</i>Generated Palladium Nanoparticles in Water under Ambient Conditions
作者:Jingming Zhao、Jiang Ye、Yong Jian Zhang
DOI:10.1002/adsc.201200704
日期:2013.2.1
practical process for the stereospecific cross-coupling of secondary allylic carbonates with arylboronic acids has been developed. The reaction is catalyzed by in situ generated palladiumnanoparticles (PdNPs) without any ligands and additional stabilizers in waterunderambientconditions and furnishes the allyl–arylcoupling products in high isolated yields with high stereospecificities as well as excellent
An efficient method for Pd-catalyzed stereospecific allyl-aryl coupling of allylic alcohols with arylboronicacids has been described. The reactions proceeded smoothly in the presence of Pd2(dba)3.CHCl3 and racemic BINAP under mild and neutral conditions, affording allyl-aryl coupling products in moderate to high yields with excellent stereospecificities.