Hydrogen-bond-assisted transition-metal-free catalytic transformation of amides to esters
作者:Changyu Huang、Jinpeng Li、Jiaquan Wang、Qingshu Zheng、Zhenhua Li、Tao Tu
DOI:10.1007/s11426-020-9883-3
日期:2021.1
interest in synthetic chemistry, biological process and pharmaceutical industry. Transition-metal, luxury ligand or excess base were always vital to the transformation. Here, we developed a transition-metal-free hydrogen-bond-assisted esterification of amides with only catalytic amount of base. The proposed crucial role of hydrogen bonding for assisting esterification was supported by control experiments
Asymmetric induction in the Michael reaction by means of chiral phase-transfer catalysts derived from cinchona and ephedra alkaloids
作者:Stefano Colonna、Alberto Re、Hans Wynberg
DOI:10.1039/p19810000547
日期:——
Asymmetricinduction in the Michaelreaction has been achieved using alkaloidonium salts in a two-phase system with optical yields of up to 36 and 26% in the addition to αβ-unsaturated ketones of thiols and nitroalkanes respectively. The presence of a hydroxy-group β to the 'onium function is essential to achieve substantial asymmetric syntheses.
Method of synthesizing optically enriched alpha-halo-esters, and product and composition therefrom
申请人:——
公开号:US20030050501A1
公开(公告)日:2003-03-13
A method of synthesizing highly optically enriched &agr;-halo-esters comprises reacting acid halides with a cinchona alkaloid catalyst and a base to form intermediate ketenes. The ketenes are reacted with electrophilic halogenating reagents to produce &agr;-halo-esters with high enantiomeric excess. The base can be an inorganic salt. The thus-formed &agr;-halo-esters have utility in synthesizing other optically-pure materials.
A deuterium‐labelingreaction of nitroalkanes in deuterium oxide and the subsequent nitroaldol reaction have been accomplished under basic and organocatalytic conditions to provide the deuterium‐labeled β‐nitroalcohols in high yields and high deuterium contents. β‐Deuterated β‐nitroalcohols could be smoothly obtained from the reaction of nitroalkanes and various electrophiles using the easily‐removal
The Development of the First Catalyzed Reaction of Ketenes and Imines: Catalytic, Asymmetric Synthesis of β-Lactams
作者:Andrew E. Taggi、Ahmed M. Hafez、Harald Wack、Brandon Young、Dana Ferraris、Thomas Lectka
DOI:10.1021/ja0258226
日期:2002.6.1
resulting from the development of a catalyzed reaction of ketenes (or their derived zwitterionic enolates) and imines. The products of these asymmetric reactions can serve as precursors to a number of enzyme inhibitors and drug candidates as well as valuable synthetic intermediates. We present a detailed study of the mechanism of the beta-lactam forming reaction with proton sponge as the stoichiometric