Direct synthesis of esters and amides from unprotected hydroxyaromatic and -aliphatic carboxylic acids.
A facile method for the activation of hydroxy-substituted carboxylic acids using benzotriazole chemistry without prior protection of the hydroxy substituents is presented. The N-acylbenzotriazole intermediates 2a-g, 6a-d, and 9a-c have been used for high-yielding synthesis of both aliphatic (3a-l) and aromatic (7a-h, 10a-f) hydroxy carboxamides. High yields of aromatic hydroxy esters 12a-h and 13a-i were obtained using either neat alcohols in neutral microwave conditions or nucleophilic alkoxides and the intermediate N-(arylacyl)benzotriazoles. Moderate yields were obtained in the case of aliphatic hydroxy esters 11a,b and thiolesters 11e-g from the intermediates 2a-c.
Katritzky
Alan R
AR
Center for Heterocyclic Compounds, University of Florida, Department of Chemistry, Gainesville, Florida 32611-7200, USA. katritzky@chem.ufl.edu
Singh
Sanjay K
SK
Cai
Chunming
C
Bobrov
Sergey
S