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Metal-Free, PPA-Mediated Fisher Indole Synthesis via Tandem Hydroamination–Cyclization Reaction between Simple Alkynes and Arylhydrazines

Authors :
Alexander V. Aksenov
Dinara C. Makieva
Rodion A. Arestov
Nikolai A. Arutiunov
Dmitrii A. Aksenov
Nicolai A. Aksenov
Alexander V. Leontiev
Inna V. Aksenova
Source :
International Journal of Molecular Sciences, Vol 25, Iss 16, p 8750 (2024)
Publication Year :
2024
Publisher :
MDPI AG, 2024.

Abstract

A new variant of Fisher indole synthesis involving Bronsted acid-catalyzed hydrohydrazination of unactivated terminal and internal acetylenes with arylhydrazines is reported. The use of polyphosphoric acid alone either as the reaction medium or in the presence of a co-solvent appears to provide the required balance for activating the C–C triple bond towards the nucleophilic attack of the hydrazine moiety without unrepairable reactivity loss of the latter due to competing amino group protonation. Additionally, the formal hydration of acetylenes to the corresponding ketones occurs under the same conditions, making it an alternative approach for generating carbonyl groups from alkynes.

Details

Language :
English
ISSN :
14220067 and 16616596
Volume :
25
Issue :
16
Database :
Directory of Open Access Journals
Journal :
International Journal of Molecular Sciences
Publication Type :
Academic Journal
Accession number :
edsdoj.8eb02c68c4e04646b0fc2a2a35613a72
Document Type :
article
Full Text :
https://doi.org/10.3390/ijms25168750