A ruthenium(II)-catalyzed highly selective Markovnikov hydrogenation of terminal epoxides to secondary alcohols is reported. Diverse substitutions on the aryl ring of styrene oxides are tolerated. Benzylic, glycidyl, and aliphatic epoxides as well as diepoxides also underwent facile hydrogenation to provide secondary alcohols with exclusive selectivity. Metal-ligand cooperation-mediated ruthenium trans-dihydride
Selective Monoacetylation of Symmetrical Diols and Selective Monodeacetylation of Symmetrical Diacetates Using HY-Zeolite as Reusable Heterogeneous Catalyst
作者:Biswanath Das、K. V. Srinivas、I. Mahender
DOI:10.1055/s-2003-42468
日期:——
HY-Zeolite has been found to be an efficient and reusable catalyst for selective monoacetylation of symmetrical diols and selective monodeacetylation of symmetrical diacetates to form the products in high yields.
The present invention provides crosslinked amine polymers effective for binding and removing bile salts from the gastrointestinal tract. These bile acid binding polymers or pharmaceutical compositions thereof can be administered to subjects to treat various conditions, including hypercholesteremia, diabetes, pruritus, irritable bowel syndrome-diarrhea (IBS-D), bile acid malabsorption, and the like.
Biocatalytic synthesis of non-vicinal aliphatic diols
作者:Ana C. Ebrecht、Jasmin C. Aschenbrenner、Martha S. Smit、Diederik J. Opperman
DOI:10.1039/d0ob02086a
日期:——
Biocatalysts are receiving increased attention in the field of selective oxyfunctionalization of C–H bonds, with cytochrome P450 monooxygenases (CYP450s), and the related peroxygenases, leading the field. Here we report on the substrate promiscuity of CYP505A30, previously characterized as a fatty acid hydroxylase. In addition to its regioselective oxyfunctionalization of saturated fatty acids (ω-1
Iterative Tandem Catalysis of Secondary Diols and Diesters to Chiral Polyesters
作者:Bart A. C. van As、Jeroen van Buijtenen、Tristan Mes、Anja R. A. Palmans、E. W. Meijer
DOI:10.1002/chem.200700818
日期:2007.10.5
The well-known dynamickineticresolution of secondary alcohols and esters was extended to secondary diols and diesters to afford chiralpolyesters. This process is an example of iterative tandem catalysis (ITC), a polymerization method where the concurrent action of two fundamentally different catalysts is required to achieve chain growth. In order to procure chiralpolyesters of high enantiomeric
众所周知的仲醇和酯的动态动力学拆分扩展到仲二醇和二酯,得到手性聚酯。此过程是迭代串联催化(ITC)的示例,它是一种聚合方法,其中需要两种根本不同的催化剂的同时作用才能实现链增长。为了获得高对映体超值(ee)和良好分子量的手性聚酯,所用的催化剂在聚合反应期间需要是互补的和相容的。我们在这里表明Shvo的催化剂和Novozym 435可以满足这些要求。1,0.5'-(1,3-亚苯基)二乙醇(1,3-二醇)和己二酸二异丙酯的最佳聚合条件要求在0.5 M 2存在下每摩尔醇基含2 mol%Shvo's催化剂和12 mg Novozym 435 ,4-二甲基-3-戊醇作为氢供体。在这些条件下,获得的手性聚酯的峰值分子量高达15 kDa,ee值高达99%,酮端基为1-3%。同样,通过结构异构体1,4-二醇,获得了手性聚酯,尽管具有较低的分子量(8.3kDa)和较低的ee(94%)。脂肪族仲二醇也产生了对