Construction of Multifunctionalized Azopyrazoles by Silver- Catalyzed Cascade Reaction of Diazo Compounds

A variety of multisubstituted azopyrazoles were synthesized in good yield from an efficient one‐pot silver trifluoromethanesulfonate (AgOTf)‐catalyzed cascade reaction of α‐diazo‐β‐keto esters with two arylhydrazines or two arylhydrazine hydrochlorides. This cascade reaction included pyrazolone form...

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Bibliographic Details
Published in:Advanced synthesis & catalysis 2015-08, Vol.357 (12), p.2657-2664
Main Authors: Pandit, Rameshwar Prasad, Lee, Yong Rok
Format: Article
Language:English
Subjects:
activation
Aromatic compounds
Bearing
Cascades
coupling
Esters
ethers
Hydrochlorides
Insertion
multifunctionalized azopyrazoles
palladium
Pyrazolones
radicals
Synthesis
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Summary:A variety of multisubstituted azopyrazoles were synthesized in good yield from an efficient one‐pot silver trifluoromethanesulfonate (AgOTf)‐catalyzed cascade reaction of α‐diazo‐β‐keto esters with two arylhydrazines or two arylhydrazine hydrochlorides. This cascade reaction included pyrazolone formation, NH insertion, and oxidation. For the synthesis of more diverse azopyrazoles bearing two different aromatic rings, the silver(I)‐catalyzed cascade reaction of 4‐diazopyrazol‐3‐one with arylhydrazine hydrochlorides was also developed. The advantages of these methodologies are easy handling, mild reaction conditions, and an effective and non‐toxic catalyst usage.
ISSN:1615-4150
1615-4169
DOI:10.1002/adsc.201500197