Synthesis and characterisation of new 4-oxo-N-(substituted-thiazol-2-yl)-4H-chromene-2-carboxamides as potential adenosine receptor ligands

• Chromones as potential adenosine receptor ligands.
• Novel 4-oxo-N-(substituted-thiazol-2-yl)-4H-chromene-2-carboxamides were synthesized.
• Compounds were characterised by NMR spectroscopy and X-ray crystallography.

Chromones are 4H-benzopyran-4-one heterocycles that have been thoroughly studied due to their interesting biological activities. Thiazole based compounds have been used in therapeutics as antimicrobial, antiviral and as antifungal agents for a long time but, in the past decades, they have been identified as potent and selective ligands for adenosine receptor. In continuation of our project related to the syntheses of pharmacologically important heterocycles, a new series of chromone–thiazole hybrids have been designed as potential ligands for human adenosine receptors. In this context, new 4-oxo-N-(substituted-thiazol-2-yl)-4H-chromene-2-carboxamides were synthesized from chromone-2-carboxylic acid by two different amidation methods. The development of dissimilar synthetic approaches provided the possibility of working with diverse reaction conditions, namely with conventional heating and/or microwave irradiation. The structure of the compounds has been established on the basis of NMR and MS spectroscopy and X-ray crystallography. Relevant data related to the molecular geometry and conformation of the chromone–thiazole hybrids has been acquired which can be of the utmost importance to understand ligand–receptor binding.

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