One Pot Regioselective Synthesis and Antimicrobial Studies of Some Novel Indazolyl-Thiazole Derivatives

2-Benzylidene-1-tetralones, obtained via Claisen condensation of 1-tetralones with aromatic aldehydes, in one pot condensation with thiosemicarbazide/semicarbazide and -haloketones in the presence of trifluoroethanol and conc. HCl gives rise to a series of new substituted-3,3a,4,5-tetrahydro-2H-benzo[g]indazol-2yl-thiazoles. The condensation was also carried out in two steps, and the intermediates 3-substituted-3,3a,4,5-tetrahydro-2H-benzo[g]indazole-2-carbothioamides/carboxamides, obtained in the first step by the reaction of 2-bezylidene-1-tetralones with thiosemicarbazide/semicarbazide, on reaction with -haloketones gives rise to indazolyl-thiazoles. A detailed X-ray diffractometry of intermediate (3aR)-3-phenyl-3,3a,4,5-tetrahydro-2H-benzo[g]indazole-2-carbothioamide were carried out to establish its crystal structure. Further, density functional theory studies on (3aR)-3-phenyl-3,3a,4,5-tetrahydro-2H-benzo[g]indazole-2-carbothioamide and its regioisomer were carried out. There is good correlation between the theoretical and experimental spectral data. The antibacterial and antifungal activities of the selected compounds were examined, and some are found to exhibit excellent activities.