Ultrasound Assisted Synthesis, X-Ray Diffraction, DFT and Antibacterial Studies of Naphthalenyl-hydrazinyl- and Quinazolinyl-thiazole Derivatives

Naphthalenyl-hydrazinecarbothioamides 2, obtained from reaction of 1-tetralones (1) and thiosemicarbazide, on condensation with ethyl bromopyruvate under ultrasonic conditions furnished thiazole-4-carboxylates (3). Ultrasound assisted synthesis of quinazoline-thiazole hybrids 5 was achieved from reaction of quinazolinyl-thiones (4) with 3-chloropentane-2,4-dione. The structural elucidation of novel compounds was determined with the help of spectral techniques. X-ray crystallographic studies (SCXRD) of single crystal of thiazole-4-carboxtylate 3a along with supramolecular interactions in crystal packing were also reported. In silico studies of regioisomers 5 and 6 were computed to correlate the experimental and theoretical spectral data. Compound 5a has shown good activity against S. aureus (MIC 25 µg/mL) and E. coli (50 µg/mL) bacterial strains.