PPh<sub>3</sub>
/Selectfluor-Mediated Transformation of Carboxylic Acids into Acid Anhydrides and Acyl Fluorides and Its Application in Amide and Ester Synthesis
An efficient synthesis of acid anhydrides or acyl fluorides mediated by PPh3/Selectfluor synstem is reported. Mechanistic studies show that the reaction proceeds through active species of acyloxyphosphonium ions, which can be quickly converted into the final products in situ by a second carboxylicacid or F–.
Experimental evidence is presented indicating that hydrolysis of an ester by superoxide in an aprotic solvent does not proceed via the corresponding acyl peroxide, although the peroxycarboxylate anion is involved.
Size-Driven Inversion of Selectivity in Esterification Reactions: Secondary Beat Primary Alcohols
作者:Stefanie Mayr、Marta Marin-Luna、Hendrik Zipse
DOI:10.1021/acs.joc.0c02848
日期:2021.2.19
alcohols carrying large aromatic side chains with anhydrides differing in size and electronic structure have been measured. While primary alcohols react faster than secondary ones in transformations with monosubstituted benzoic anhydridederivatives, relative reactivities are inverted in reactions with sterically biased 1-naphthyl anhydrides. Further analysis of reaction rates shows that increasing substrate
Annelated Pyridine Bases for the Selective Acylation of 1,2‐Diols
作者:Stefanie Mayr、Hendrik Zipse
DOI:10.1002/ejoc.202101521
日期:2022.8.5
The acylation of primary over secondary hydroxyl groups in 1,2-ethanediols depends strongly on size effects and noncovalent interactions between the alcohol side chains and the catalysts surface.
Redesign of Rifamycin Antibiotics to Overcome ADP‐Ribosylation‐Mediated Resistance
作者:Tian Lan、Uday S. Ganapathy、Sachin Sharma、Yong‐Mo Ahn、Matthew Zimmerman、Vadim Molodtsov、Pooja Hegde、Martin Gengenbacher、Richard H. Ebright、Véronique Dartois、Joel S. Freundlich、Thomas Dick、Courtney C. Aldrich
DOI:10.1002/anie.202211498
日期:2022.11.7
The first antibiotics with low nanomolar activity against the multidrug-resistant Mycobacterium abscessus are achieved by rational redesign of rifamycins. Structure-based modification on the rifamycin ansa-chain, together with microbiological, biochemical, biophysical and in vivo characterizations, provides novel candidates that are 300-fold more active than rifampicin, completely bypass the resistance