An elegant microwave assisted environmentally benign approach to the synthesis of novel 3’- [4’-N-{ 4-methyl-2-pyrimidinyl }-benzene suphonamido]-spiro-(3H-indol-3,2’-thiazolidin)-1H- 2,4’ (5H) dione (5) and their Mannich’s bases 6( a-g) has been described. Treatment of isatin (1) with sulphamerazine (2) yielded 4-[1, 2-dihydro-2-oxo-3H-indol-3-ylidene] amino]-N (4-methyl- 2-pyrimidinyl) benzene sulfonamide (3). Cyclocondensation of its azomethine function with mercaptoacetic acid (4) over basic alumina afforded 3,-[4-N {4-methyl-2-pyrimidinyl}-benzene sulphonamido]-spiro-(3H-indol-3, 2’-thiazolidin)-1H-2, 4’ (5H’) dione) (5) which reacted smoothly with secondary amines and formaldehyde to give Mannich’s bases 6(a-g) in excellent yield. Mannich’s bases of sulphamerazinyl substituted [spiro-indolo-4-thiazolidinone] 6(a-g) were screened for their in-vitro antimicrobial activities against bacterial species (E.coli and B.substilis) and fungal species (A.niger and A.flavus) by Agar-well assay method against the standard drugs (ciprofloxacin for bacteria and flucanazol for fungi).
