An efficient, one-pot, regioselective synthesis of 2-aryl/hetaryl-4-methyl-5-acylthiazoles under solvent-free conditions

Abstract

In this article, we present an efficient, one-pot regioselective approach towards the synthesis of 2-aryl/hetaryl-4-methyl-5-acylthiazoles obtained during the reaction of α-bromo-1,3-diketones generated in situ by triturating unsymmetrical 1,3-diketones with N-bromosuccinimide, with various thioamides under solvent-free conditions. This environmentally benign protocol showed large functional group tolerance, resulted in the exclusive formation of a single isomer, out of the two possible regioisomers in admirable yields. The structure of the isomeric thiazole was assigned unambiguously on the basis of multinuclear NMR [(¹H-¹³C) HMBC, (¹H-¹³C) HMQC, (¹H-¹⁵N) HMBC] and X-ray crystallographic studies. The entire protocol is ecologically desirable as it employs no organic solvent.

GRAPHICAL ABSTRACT

KEYWORDS:

• Unsymmetrical 1,3-diketones
• N-bromosuccinimide
• thioamides
• 2-aryl/hetaryl-4-methyl-5-acylthiazoles
• multinuclear 2D NMR

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

We are thankful to the Council of Scientific and Industrial Research, India for providing financial assistance (SRF) to Mona Hooda. We are also thankful to Haryana State Council for Science and Technology (HSCST), Haryana for providing financial support to project fellow Namam Jain. Dionisia Sanz and Rosa M. Claramunt thank the Spanish Ministerio de Econonomia, Industria y Competitividad (Ministerio de Economia, Industria y Competitividad, Gobierno de Espana) [CTQ 2014-56833-R] for financial support.