A One-pot Approach to Ethyl 1,4,5-Triaryl-1<i>H</i>-pyrazole-3-carboxylates via an Improved Claisen Condensation-Knorr Reaction Sequence
作者:Jiaojiao Zhai、Chunhui Gu、Jianan Jiang、Shunli Zhang、Daohua Liao、Lei Wang、Dunru Zhu、Yafei Ji
DOI:10.1002/cjoc.201300776
日期:2013.12
one‐pot approach to ethyl 1,4,5‐triaryl‐1H‐pyrazole‐3‐carboxylates has been developed in moderate to high yields. The tert‐BuOLi‐mediated Claisen condensation of 1,2‐diarylethanones and ethyl oxalyl chloride efficiently provided the enolized lithium salts of ethyl 2,4‐dioxo‐3,4‐diarylbutanoates, which in situ reacted with arylhydrazine hydrochlorides via a hydrochloric acid‐promoted Knorr reaction to produce