A regio- and stereoselective 1,3-dipolar cycloaddition for the synthesis of novel spiro-pyrrolothiazolyloxindoles and their antitubercular evaluation.

The 1,3-dipolar cycloaddition of azomethine ylides derived from substituted isatins and 1,3-thiazolane-4-carboxylic acid to a series of 2-(arylmethylene)-2,3-dihydro-1H-inden-1-ones afforded twenty nine novel spiro-pyrrolothiazolyloxindoles regio- and stereoselectively in moderate yields. These compounds were screened for their in vitro activity against Mycobacterium tuberculosis H37Rv (MTB) using agar dilution method. Among 29 compounds screened, spiro[5.3']-5'-nitrooxindole-spiro-[6.3″]-2,3-dihydro-1H-inden-1″-one-7-(2,3-dichlorophenyl)tetrahydro-1H-pyrrolo[1,2-c][1,3]thiazole, was found to be the most active compound with MIC of 2.8 μM against MTB, being 1.67 and 2.70 times more active than ciprofloxacin and ethambutol respectively.