Easily Accessible and Highly Tunable Bisphosphine Ligands for Asymmetric Hydroformylation of Terminal and Internal Alkenes
作者:Kun Xu、Xin Zheng、Zhiyong Wang、Xumu Zhang
DOI:10.1002/chem.201304684
日期:2014.4.7
An efficient methodology for synthesizing a small library of easily tunable and sterically bulky ligands for asymmetric hydroformylation (AHF) has been reported. Five groups of alkene substrates have been tested with excellent conversions, moderate‐to‐excellent regio‐ and enantioselectivities. Among the best result of the reported literature, application of ligand 1 c in the highly selective AHF of
Asymmetric Dehydrative Cyclization of ω-Hydroxy Allyl Alcohols Catalyzed by Ruthenium Complexes
作者:Shinji Tanaka、Tomoaki Seki、Masato Kitamura
DOI:10.1002/anie.200904671
日期:2009.11.9
New axially chiral ligands and their allyl esters have been designed and synthesized. The combination of these ligands with [CpRu(CH3CN)3]PF6 has realized highly efficient intramolecular dehydrative cylization of ω‐hydroxy allylalcohols, to give α‐alkenyl‐substituted cyclic ethers with up to greater than 99:1 enantiomeric ratio without activation of the allylic moieties (see scheme; Cp=cyclopentadienyl
1-Alkoxyallene as an Effective Precursor for Regio- and Stereocontrolled Allylation Reactions with Aliphatic Aldehydes via Bis-Stannylation
作者:David R. Williams、Micheal W. Fultz
DOI:10.1021/ja054201k
日期:2005.10.1
Bis-stannylation of 1-(methoxy)methoxyallene yields (E)-(3-(methoxymethoxy)prop-2-ene-1,2-diyl) bis-tributylstannane (2) as a highly reactive allylation reagent. Stereoselectivereactions of functionalized stannane 2 with a variety of aldehydes provide good yields of 1,2-diol derivatives. Reactions with alpha-alkoxyaldehydes proceed with chelation-controlled addition to afford efficient constructions
1-(甲氧基)甲氧基丙二烯的双-甲锡烷基化产生(E)-(3-(甲氧基甲氧基)丙-2-烯-1,2-二基)双-三丁基锡烷(2)作为高反应性烯丙基化试剂。官能化锡烷 2 与各种醛的立体选择性反应提供了良好的 1,2-二醇衍生物产率。与 α-烷氧基醛的反应通过螯合控制加成进行,以在带有三个不同氧(烷氧基和羟基)取代基的立体三联体中有效构建 3,4-反-4,5-syn-关系。提出了机械方面的考虑,核磁共振实验的衍生物支持立体化学分配。包括 X 射线衍射研究。
Zirconium(IV)- and Hafnium(IV)-Catalyzed Highly Enantioselective Epoxidation of Homoallylic and Bishomoallylic Alcohols
作者:Zhi Li、Hisashi Yamamoto
DOI:10.1021/ja100951u
日期:2010.6.16
enantioselective epoxidation of homoallylic alcohols and bishomoallylic alcohols, which used to be quite difficult substrates for other types of asymmetricepoxidation reactions. The performance of the catalyst was improved by adding polar additive and molecular sieves. For homoallylic alcohols, the reaction could provide epoxy alcohols in up to 83% yield and up to 98% ee, while, for bishomoallylic alcohols, up
Libraries of Bisdiazaphospholanes and Optimization of Rhodium-Catalyzed Enantioselective Hydroformylation
作者:Tyler T. Adint、Gene W. Wong、Clark R. Landis
DOI:10.1021/jo400525w
日期:2013.5.3
is generally most effective. However, optimal regio- and enantioselectivehydroformylation of 2,3-dihydrofuran (up to 3.8:1 α-isomer/β-isomer ratio and 90% ee for the α-isomer) and 2,5-dihydrofuran (up to <1:30 α-isomer/β-isomer ratio and 95% ee for the β-isomer) arises from bisdiazaphospholanes containing tertiary carboxamides. Hydroformylation of either 2,3- or 2,5-dihydrofuran yields some of the β-formyl