Development and application of versatile bis-hydroxamic acids for catalytic asymmetric oxidation
作者:Allan U. Barlan、Wei Zhang、Hisashi Yamamoto
DOI:10.1016/j.tet.2007.03.071
日期:2007.7
preliminary results of our new designed C(2)-symmetric bis-hydroxamic acid (BHA) ligands and the application of the new ligands for vanadium-catalyzed asymmetric epoxidation of allylic alcohols as well as homoallylic alcohols. From this success we demonstrate the versatile nature of BHA in the molybdenum catalyzed asymmetric oxidation of unfunctionalized olefins and sulfides.
Chemoenzymatic synthesis of monocyclic arene oxides and arene hydrates from substituted benzene substrates
作者:Derek R. Boyd、Narain D. Sharma、Vera Ljubez、Peter K. M. McGeehin、Paul J. Stevenson、Marine Blain、Christopher C. R. Allen
DOI:10.1039/c3ob40166a
日期:——
Reduction of a substituted areneoxide to yield a racemicarene hydrate was observed. Arene hydrates have also been synthesised, in enantiopure form, from the corresponding dihydroarene oxide or trans-bromoacetate precursors. Biotransformation of one arene hydrate enantiomer resulted in a toluene-dioxygenase catalysed cis-dihydroxylation to yield a benzene cis-triol metabolite.
Enantioselective, Stereoconvergent Resolution Copolymerization of Racemic
<i>cis</i>
‐Internal Epoxides and Anhydrides
作者:Guang‐Hui He、Bai‐Hao Ren、Shi‐Yu Chen、Ye Liu、Xiao‐Bing Lu
DOI:10.1002/anie.202011259
日期:2021.3.8
unreacted epoxide at various conversions. Catalytic activity and copolymer enantioselectivity are strongly influenced by the phenolate ortho‐substituents of the ligand set, as well as the axial linker and its chirality. An enantiopure binaphthol‐linked bimetallic AlIII complex allows stereoconvergent access to the stereoregular semi‐crystalline polyesters and a concomitant kinetic resolution of the
外消旋的顺式-内部环氧化物和酸酐的前所未有的对映选择性拆分共聚反应,是由具有多个手性的双核铝配合物介导的,提供了具有两个连续立体中心的旋光聚酯,以及未反应的底物具有良好的对映选择性。在该拆分共聚中观察到了意外的立体收敛,其中共聚物的对映选择性形成的选择性因子大大超过了在各种转化率下基于未反应的环氧化物的动力学拆分系数。催化活性和共聚物的对映选择性受配体组的酚酸酯邻位取代基,轴向连接基及其手性的影响很大。对映纯联萘酚双金属Al III 配合物可以使立体收敛地接触到有规立构的半结晶聚酯,并伴随着环氧底物的动力学拆分。
Regioselective SN2 Opening of Vinylic Epoxides with Trialkylzincates and Trialkylaluminates
The use of trialkylorganozincates and tetraalkylaluminates allows regioselective SN2 nucleophilic opening of vinylic epoxides. The reaction occurs with an anti-substitution pattern and can be applied to a wide range of substrates. We also show that the solvent and the structure of the epoxide have an influence on the substitution products ratio.
Conversion of racemic allylic hydroperoxides into corresponding chiral 1/2,3-triols by using catalytic OsO$_{4}$ and chiral cinchona ligands in the absence of co-oxidant
作者:Haydar GÖKSU、Mehmet Serdar GÜLTEKİN
DOI:10.3906/kim-1411-68
日期:——
For the first time, removal of oxygen atoms from allylic hydroperoxide functionality and reintroduction to the double bond was achieved using catalytic OsO$_4}$ and chiral cinchona alkaloid derivatives in an acetone-water mixture to give corresponding chiral 1/2,3-triol with an enantioselectivity up to 99% ee. The hydroperoxide group was used as both a co-oxidant and a source of hydroxyl groups. This protocol is thought to have potential to provide opportunities for chiral synthesis of 1/2,3-triols from corresponding allylic hydroperoxides in the absence of co-oxidant in one stage for the first time in the literature.