Related Experiment Video
Updated: Jun 4, 2026

Facile Preparation of 4-Substituted Quinazoline Derivatives
Published on: February 15, 2016
An straightforward entry to new pyrazolo-fused dibenzo[1,4]diazepines
Susana Hernández1, Isabel Moreno, Raul SanMartin
1Kimika Organikoa II Saila, Zientzia eta Teknologia Fakultatea, Euskal Herriko Unibertsitatea, PO Box 644, 48080, Bilbao, Spain.
Abstract:
A series of novel pyrazolodibenzo[1,4]diazepines has been synthesized with good overall yields. The diarylpyrazole intermediates, with structure similarity to biologically relevant compounds such as currently marketed drugs like rimonabant or celecoxib, were prepared by a tandem sequence amine-exchange/heterocyclization starting from readily available enaminones and arylhydrazines. The key step of this efficient methodology was C(aryl)-N bond construction, accomplished by a palladium-catalyzed intramolecular N-arylation reaction, which was conducted in both homogeneous and polymer-supported versions. Reaction scope of such protocols and recycling of the heterogeneous catalyst were also examined.
Related Concept Videos
Diazonium Group Substitution with Halogens and Cyanide: Sandmeyer and Schiemann Reactions
Nucleophilic Aromatic Substitution of Aryldiazonium Salts: Aromatic SN1
In the Sandmeyer reaction, for example, the diazonio group is replaced by a chloro, bromo, or cyano...
Aryldiazonium Salts to Azo Dyes: Diazo Coupling
Diazonium Group Substitution: –OH and –H
1° Amines to Diazonium or Aryldiazonium Salts: Diazotization with NaNO2 Overview
The nitrous acid is unstable. Hence, it is formed in situ from a solution of sodium nitrite and cold aqueous acids such as hydrochloric or sulfuric acid. In an acidic solution, the –OH group of nitrous acid undergoes protonation to give oxonium ion, followed by water loss...
1° Amines to Diazonium or Aryldiazonium Salts: Diazotization with NaNO2 Mechanism

