Synthesis 2023; 55(07): 1150-1158
DOI: 10.1055/s-0042-1751770
paper

Copper(I)-Catalysed Reaction of Hydrazonyl Chlorides with Homopropargylic Alcohols: Regioselective Synthesis of 5-Substituted Pyrazoles

Alessandra Silvani
,
Marco Manenti
,
Giorgio Molteni
The authors were financially supported by the Department of Chemistry of the Università degli Studi di Milano (PSR2020_DIP_005_PI).


In memory of Professor Geatano Zecchi. With admiration and gratitude, G.M. remembers his depth of thinking and immense knowledge of heterocyclic chemistry.

Abstract

Fully regioselective synthesis of 5-hydroxyethylpyrazoles was exploited by reacting hydrazonoyl chlorides with homopropargylic alcohols in the presence of catalytic amounts of copper(I) chloride. Good yields of pyrazolic products and mild reaction conditions were experienced notwithstanding the known, poor reactivity of homopropargylic alcohols towards hydrazonoyl chlorides. The role of copper(I) ion and some mechanistic insights for the formation of reaction products are also discussed.

Supporting Information



Publikationsverlauf

Eingereicht: 07. Oktober 2022

Angenommen nach Revision: 14. November 2022

Artikel online veröffentlicht:
28. November 2022

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