Regio‐ and Stereoselective Chan‐Lam‐Evans Enol Esterification of Carboxylic Acids with Alkenylboroxines
作者:Luuk Steemers、Linda Wijsman、Jan H. van Maarseveen
DOI:10.1002/adsc.201800914
日期:2018.11.5
Efficient and scalable Cu(II)‐mediated enol esterification methodology of carboxylicacids from alkenyl boroxines and boronic acids is presented. The reaction shows a wide scope in aliphatic and aromatic carboxylicacids in combination with several alkenyl boroxines. In the case of 2‐substituted alkenyl boroxines the double bond configuration was fully retained in the enol ester product. Also N‐hydroxyimides
Dinuclear Zinc-Catalyzed Asymmetric Desymmetrization of Acyclic 2-Substituted-1,3-Propanediols: A Powerful Entry into Chiral Building Blocks
作者:Barry M. Trost、Sushant Malhotra、Takashi Mino、Naomi S. Rajapaksa
DOI:10.1002/chem.200800623
日期:2008.8.28
The asymmetric acylation of meso-2-substituted-1,3-propanediols by using an amphoteric chiraldinuclear zinc catalyst is described. It is has been demonstrated that both 2-alkyl- and 2-aryl-1,3-propanediols can be desymmetrized in high yields and enantioselectivities by using the same family of ligands. Given that both antipodes of the chiral catalyst are available, both enantiomers of the desymmetrized
The vinyl benzoate derivatives were successfully synthesized by the transvinylation reactions that vinyl group transferred from vinylacetate to aromatic carboxylic acids with the recoverable catalyst RhCl3·3H2O. This catalyst features air stable and tolerance of water, good reusable ability, meanwhile, shows high selectivity for aromatic carboxylic acid in the presence of phenolic hydroxyl. With this
Rhodium-Catalyzed β-Selective Oxidative Heck-Type Coupling of Vinyl Acetate via C–H Activation
作者:Hui-Jun Zhang、Weidong Lin、Feng Su、Ting-Bin Wen
DOI:10.1021/acs.orglett.6b03244
日期:2016.12.16
An efficient Rh(III)-catalyzed direct ortho-C–H olefination of acetanilides with vinylacetate was developed. This protocol provides a straightforward pathway to a series of (E)-2-acetamidostyryl acetates, giving access to indole derivatives following a simple hydrolysis/cyclization process.
the first biocatalytic modification of sesquiterpenelactones (STL) found in chicory plants. Regioselective O-acylation of their primary alcohol group is achieved by the immobilized lipase B from Candida antarctica, with various aliphatic vinyl esters as acyl donors. High conversion rates were observed, facilitating the synthesis of novel semi-synthetic STL ester derivatives with promising pharmaceutical
本文报道了在菊苣植物中发现的倍半萜内酯 (STL) 的首次生物催化修饰。其伯醇基团的区域选择性O-酰化是通过来自南极假丝酵母的固定化脂肪酶 B 以各种脂肪族乙烯基酯作为酰基供体实现的。观察到高转化率,促进了具有良好药物应用前景的新型半合成STL酯衍生物的合成。