Electrochemical Regioselective C(sp2)-H Bond Chalcogenation of Pyrazolo[1,5-a]pyrimidines via Radical Cross-Coupling
Abhinay S Chillal1, Rajesh T Bhawale1, Siddharth Sharma2
1Department of Chemistry, Indian Institute of Technology Indore, Khandwa Road, Indore 453552, India.
Abstract:
Herein, we disclose an electrochemical approach for the C(sp2)-H chalcogenation of pyrazolo[1,5-a]pyrimidines. This technique offers an oxidant and catalyst-free protocol for achieving regioselective chalcogenation of pyrazolo[1,5-a]pyrimidines. The procedure uses only 0.5 equiv. of diaryl chalcogenides which underscores the atom economy of the protocol. Key attributes of this methodology include mild reaction conditions, short reaction time, utilization of cheap electrode materials, and eco-friendly reaction conditions. Cyclic voltammetry studies and radical quenching experiments revealed a radical cross-coupling pathway for the reaction mechanism.
More Related Videos
11:44Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-phosphinetriyltripiperidine]}palladium Under Mild Reaction Conditions
Published on: March 20, 2014
09:12[DPEPhosbcpCu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst
Published on: May 21, 2019
Related Concept Videos
Photochemical Electrocyclic Reactions: Stereochemistry
Selection Rules: Photochemical Activation
Thermal Electrocyclic Reactions: Stereochemistry
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Radicals: Electronic Structure and Geometry
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
Thermal and Photochemical Electrocyclic Reactions: Overview
Electrophilic Aromatic Substitution: Chlorination and Bromination of Benzene
Aryldiazonium Salts to Azo Dyes: Diazo Coupling
