ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Regioselective C₃-N alkylation of coumarins under solvent-free conditions: a graphene oxide nanosheet promoted novel strategy for C-N bond formation via azide-alkene 1,3-dipolar cycloaddition reaction

Nazia Kausar, Mohd Afzal, Abdullah Alarifi, Somdatta Maiti, and Abdulla Al Masum

Department of Chemistry, Government General Degree College, Kaliganj, Debagram, Nadia, India

E-mail: naziakausar54@gmail.com

Received: 19 September 2024  Accepted: 26 January 2025

Abstract:

A carbocatalytic, regioselective synthesis of C₃-N alkylated coumarins has been reported under solvent-free conditions. This synthetic protocol provides a series of C₃-N alkylated coumarins in good yields starting directly from coumarins and azides in the presence of GO nanosheets without any additives or ligands needed. In contrast to the frequently applied synthetic strategy that involves nucleophilic substitution of benzylamine/benzyl alcohol with halogenated coumarins in the presence of Pd or Cu catalyst for the generation of N-alkylated coumarins, here, coumarins directly reacts with azides via azide-alkene 1,3-dipolar cycloaddition/ring cleavage/1,2-H migration/denitrogenation, followed by 1,3-H migration to afford C₃-N alkylated coumarins.

Keywords: Azides; C3-N substituted coumarins; C-N bond formation; Coumarins; Regioselective synthesis; Solvent-free; 1,3-dipolar cycloaddition

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-025-03929-5

Chemical Papers 79 (4) 2347–2356 (2025)