A Phosphetane Catalyzes Deoxygenative Condensation of α-Keto Esters and Carboxylic Acids via P<sup>III</sup>/P<sup>V</sup>═O Redox Cycling
作者:Wei Zhao、Patrick K. Yan、Alexander T. Radosevich
DOI:10.1021/ja511889y
日期:2015.1.21
A small-ring phosphacycle is found to catalyze the deoxygenative condensation of α-keto esters and carboxylic acids. The reaction provides a chemoselective catalytic synthesis of α-acyloxy ester products with good functional group compatibility. Based on both stoichiometric and catalytic mechanistic experiments, the reaction is proposed to proceed via catalytic P(III)/P(V)═O cycling. The importance
Tropylium-Catalyzed O–H Insertion Reactions of Diazoalkanes with Carboxylic Acids
作者:Claire Empel、Thanh Vinh Nguyen、Rene M. Koenigs
DOI:10.1021/acs.orglett.0c04069
日期:2021.1.15
describe the application of a nonbenzenoid aromatic carbocation, namely tropylium, as an organic Lewis acid catalyst in O–H functionalization reactions of diazoalkanes with benzoic acids. The newly developed protocol is applicable to a wide range of diazoalkane and carboxylic acid substrates with excellent efficiency (43 examples, up to 99% yield).
Hydroacylation of Activated Ketones Catalyzed by <i>N</i>-Heterocyclic Carbenes
作者:Audrey Chan、Karl A. Scheidt
DOI:10.1021/ja060833a
日期:2006.4.1
N-heterocyclic carbenes derived from triazolium salts are effective catalysts between 10 and 15 mol % for the hydroacylation of activated ketones. The reducing equivalent is generated via the interaction of a nucleophilic carbene species and an aromatic aldehyde. The subsequent alcohol product can undergo an acylation event with the resulting acyl heteroazolium intermediate formed in situ between the NHC and the aldehyde. This unprecedented multiple bond-forming reaction can accommodate aromatic aldehydes as the hydride source and various electron-deficient ketones. Preliminary mechanistic evidence indicates that the reduction and acylation steps are sequential operations. The intramolecular variant of this organocatalytic reaction affords benzofuranones in good yield.
Carboxylic Acid Functionalization Using Sulfoxonium Ylides as a Carbene Source
作者:Fathima Febin Koothradan、Anusree Suresh Babu、Krishnendu P. Pushpakaran、Arumugam Jayarani、Chinnappan Sivasankar