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Paper | Regular issue | Vol 100, No. 6, 2020, pp.916-933
Published online, 28th April, 2020
DOI: 10.3987/COM-20-14251
Highly Regioselective Synthesis of 1-Acyl-5-hydroxypyrazolines or Synthesis of 3,5-Disubstituted Pyrazoles from (E)-β-Chlorovinyl Ketones and Benzohydrazides or Hydrazine Hydrate

Haotian Wu, Rongrong Hou, Ye Yuan, Jingli Zhang,* Bifeng Chen, and Taolei Sun*

*School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, 122 Luoshi Road,Wuhan,Hubei 430070, China

Abstract

Highly regioselective synthesis of 1-acyl-5-hydroxypyrazolines or synthesis of 3,5-disubstituted pyrazoles have been achieved through the cyclocondensation of (E)-β-chlorovinyl ketones with benzohydrazides/hydrazine hydrate under extremely mild reaction conditions. The mechanistic studies showed that diverse electrophilic pathways of (E)-β-chlorovinyl ketones could be observed by using different nucelophilic species. Moreover, the utility of the tandem reaction is further illustrated by the concise synthesis of 1-acyl-pyrazole and 3-pentyl-5-phenyl-1H-pyrazole.