Synthesis 2020; 52(04): 591-601
DOI: 10.1055/s-0039-1690239
paper
© Georg Thieme Verlag Stuttgart · New York

A Greener Approach for the Chemoselective Boc Protection of Amines Using Sulfonated Reduced Graphene Oxide as a Catalyst in Metal- and Solvent-Free Conditions

Rupali Mittal
,
Anupam Mishra
,
Chemical Biology Laboratory, Department of Chemistry, University of Delhi, Delhi 110007, India   Email: satishpna@gmail.com
› Author Affiliations
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Publication History

Received: 07 August 2019

Accepted after revision: 14 October 2019

Publication Date:
06 November 2019 (online)


This research article is dedicated to Prof. S. Chandrasekaran, Department of Organic Chemistry, Indian Institute of Science, Bangalore, India on the occasion of his 74th birthday

Abstract

Sulfonated reduced graphene oxide (SrGO) has displayed great potential as a solid acid catalyst due to its efficiency, cost-effectiveness, and reliability. In this study, SrGO was synthesized by the introduction of sulfonic acid-containing aryl radicals onto chemically reduced graphene oxide using ultrasonication. The SrGO catalyst was characterized by Fourier Transform Infrared (FTIR) spectroscopy, Raman spectroscopy, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and transmission electron microscopy (TEM). Further, SrGO was effectively utilized as a metal-free and reusable solid acid catalyst for the chemoselective N-t-Boc protection of various aromatic and aliphatic amines under solvent-free conditions. The N-t-Boc protection of amines was easily achieved under ambient conditions affording high yields (84–95%) in very short reaction times (5 min–2 h). The authenticity of the approach was confirmed by a crystal structure. The catalyst could be easily recovered and was reused up to seven consecutive catalytic cycles without any substantial loss in its activity.

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