不对称羟基羰基化是合成羧酸的最基本但最具挑战性的方法之一。在此,我们报道了钯催化的乙烯基芳烃与 CO 和水的高度对映选择性马尔可夫尼科夫羟基羰基化的发展。单齿亚磷酰胺配体L6反应中起重要作用。该反应耐受一系列官能团,并为一系列 2-芳基丙酸(包括几种常用的非甾体抗炎药)提供了一种简便且原子经济的方法。该催化体系还使乙烯基芳烃与醇发生不对称马尔科夫尼科夫氢烷氧基羰基化反应,得到 2-芳基丙酸酯。机理研究表明,氢化钯是不可逆的,是区域和对映体决定步骤,而水解/醇解可能是限速步骤。
n of alkenes with anilines has been developed for the atom-economical synthesis of 2-substituted propanamides bearing an α-stereocenter. A novel phosphoramidite ligand L16 was discovered which exhibited very high reactivity and selectivity in the reaction. This asymmetric Markovnikov hydroaminocarbonylation employs readily available starting materials and tolerates a wide range of functional groups
TCFH–NMI: Direct Access to <i>N</i>-Acyl Imidazoliums for Challenging Amide Bond Formations
作者:Gregory L. Beutner、Ian S. Young、Merrill L. Davies、Matthew R. Hickey、Hyunsoo Park、Jason M. Stevens、Qingmei Ye
DOI:10.1021/acs.orglett.8b01591
日期:2018.7.20
Challenging couplings of hindered carboxylic acids with non-nucleophilic amines to form amide bonds can be accomplished in high yields, and in many cases, with complete retention of the adjacent stereogenic centers using the combination of N,N,N′,N′-tetramethylchloroformamidinium hexafluorophosphate (TCFH) and N-methylimidazole (NMI). This method allows for in situ generation of highly reactive acyl imidazolium
Reaction of azides and enolisable aldehydes under the catalysis of organic bases and Cinchona based quaternary ammonium salts
作者:Dario Destro、Sandra Sanchez、Mauro Cortigiani、Mauro F. A. Adamo
DOI:10.1039/c7ob00799j
日期:——
preparation of amides starting from azides and enolisable aldehydes. The reaction proceeded via the formation of triazoline intermediates that were converted into amides via Lewis acid catalysis. Preliminary studies on the preparation of triazolines under chiral phasetransfercatalysis are also presented, demonstrating that enantioenriched amides could be prepared from achiral aldehydes in moderate to low
The highly enantioselective synthesis of chiral amides was achieved by an asymmetric Wolff rearrangement. A bifunctional phosphoric acid catalyst not only expedited the transformation but also controlled the enantioselectivity. The developed method enables the asymmetric addition between potent nucleophilic reagents and ketene species and provides a new approach to chiral amides.