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Six new salts of an API intermediate 2-aminothiazole with different carboxylic acid coformers were synthesized and characterized by IR (Infrared spectroscopy), 1H-NMR, DSC (Differential scanning calorimetry), XRPD (X-ray powder diffraction) and single crystal XRD. The crystal structure of the salts with benzoic acid, 2,3-, 2,4-, 2,5-, 2,6- dihydroxybenzoic acids and 2,4-dinitrobenzoic acid were determined. The thiazole moiety exhibited solvent (polarity) assisted tautomerism in all reported salts and proton transfer was noticed to the ring N of thiazole due to which two point supramolecular synthon N+−H(thiazole)⋯O−(acid), N−H(amine)⋯O−(acid) was observed. The crystal structures were studied with respect to the positional effect of the competing functional groups like hydroxyl (−OH) and nitro (−NO2) as well as their donor and acceptor abilities for hydrogen bonding. The presence of the non-conventional hydrogen bond (C−H⋯O) has been found to play a critical role in the formation of secondary supramolecular architectures.

A series of 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-ones have been synthesized by the multicomponent reaction (MCR) of β-naphthol, aryl aldehydes, and dimedone by using BF3:OEt2 as a catalyst. The derived compounds have been analyzed by IR, NMR (1D and 2D), and mass spectra. The single crystal X-ray structural analysis of 9,9-dimethyl-12-(2-nitrophenyl)-8,9,10,12-tetrahydrobenzo[a]-xanthen-11-one evidences the envelope conformation of the cyclohexane ring and the pyran ring tends to adopt flattened-boat conformation.