Chemoselective Esterification and Amidation of Carboxylic Acids with Imidazole Carbamates and Ureas
摘要:
Imidazole carbamates and ureas were found to be chemoselective esterification and amidation reagents. A wide variety of carboxylic acids were converted to their ester or amide analogues by a simple synthetic procedure in high yields
Highly efficient and environmentally benign preparation of Weinreb amides in the biphasic system 2-MeTHF/water
作者:Vittorio Pace、Laura Castoldi、Andrés R. Alcántara、Wolfgang Holzer
DOI:10.1039/c3ra41262h
日期:——
A straightforward chromatography-free preparation of Weinreb amides starting from acid halides has been achieved in the biphasic medium 2-MeTHF/water. Analytically pure compounds were isolated in excellent yields simply after removal of 2-MeTHF, which absolutely avoids the use of any contaminant organic solvent within the whole process due to its (practically) immiscibility with water.
Chemoselective Esterification and Amidation of Carboxylic Acids with Imidazole Carbamates and Ureas
作者:Stephen T. Heller、Richmond Sarpong
DOI:10.1021/ol1018882
日期:2010.10.15
Imidazole carbamates and ureas were found to be chemoselective esterification and amidation reagents. A wide variety of carboxylic acids were converted to their ester or amide analogues by a simple synthetic procedure in high yields
On the reactivity of imidazole carbamates and ureas and their use as esterification and amidation reagents
作者:Stephen T. Heller、Richmond Sarpong
DOI:10.1016/j.tet.2011.09.057
日期:2011.11
The optimization, substrate scope, and mechanism of esterification and amidation of carboxylic acids mediated by imidazole-based reagents are discussed. The innate reactivity of carbonylimidazole reagents with a range of nucleophiles is also explored. New reagents developed for the synthesis of alpha,beta-unsaturated esters are described, as are reagents for the preparation of tertiary amides directly from carboxylic acids. (C) 2011 Elsevier Ltd. All rights reserved.