Strategy To Prepare 3-Bromo- and 3-Chloropyrazoles
作者:Richard J. Fox、Michael A. Schmidt、Martin D. Eastgate
DOI:10.1021/acs.joc.7b03282
日期:2018.3.2
A general strategy to prepare substituted 3-bromo- and 3-chloropyrazoles is described. The three-step method involves condensation of crotonates or β-chloro carboxylic acids with hydrazines, followed by halogenation and oxidation. Several condensation and oxidation protocols were developed to enable preparation of a wide variety of 3-halopyrazoles with good to excellent yields and regiocontrol.