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Unexpected outcome of the Zn(OTf)2-catalyzed arylhydrazination of alkanoyl propargylamines: Rapid entry into 1-(arylamino)imidazoles

Author:
Vedekhina, Tatiana, Lukin, Alexei, Krasavin, Mikhail
Source:
Tetrahedron letters 2019 pp. 151365
ISSN:
0040-4039
Subject:
Lewis acids, amines, carbon, carboxamides, catalytic activity, chemical reactions, chemical structure, imidazoles, indoles, stoichiometry, sulfonic acids, zinc chloride
Abstract:
When attempting to extend the Zn(OTf)2-catalyzed hydrazination of propargylic amides (en route to Fischer indoles) to alkanoic propargylamides, it was discovered that after the initial hydrazination event, the respective N-anilinoimidazoles are obtained. The use of stoichiometric ZnCl2 as the promoter still gave the Fischer indole product. The unexpected reaction outcome was attributed to the overly high electrophilicity of the alkanoic carboxamide carbon atom.
Agid:
6754625