Synthesis, structure and antimicrobial evaluation of new 3,3a,4,5-tetrahydro-2H-benzo[g]indazol-2-yl-thiazol-4(5H)-ones

•Synthesis of eight new indazolyl-thiazol-4(5H)-ones have been accomplished.•Stereo chemical assignments were made on the basis of spectroscopic experiments.•X-ray diffraction of one indazolyl-thiazol-4(5H)-one derivative has been reported.•Results of DFT studies on diastereoisomers are correlated with experimental values.•Newly synthesised compounds exhibit promising antimicrobial activities.

The reaction of semicarbazide or thiosemicarbazide with 2-arylidene-1-tetralones under alkaline condition affords 3,3a,4,5-tetrahydro-2H-benzo[g]indazole-2-carbo(thio)amides as a mixture of cis and trans diastereoisomers of 3-H and 3a-H. The synthesis of new indazolyl-thiazol-4(5H)-ones from the condensation of cis isomer and α-halo acids is reported. A DFT study along with X-ray single crystal data of a representative compound is presented. All the eight newly synthesised indazolyl-thiazol-4(5H)-ones were screened for their antibacterial and antifungal activities and some compounds have shown promising activities.

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