Microwave assisted synthesis of 3,6-disubstituted-5,6-dihydro-s-triazolo (3,4-b) (1,3,4)-thiadiazoles and their biological activities

3-Carbethoxy coumarin (1) on treatment with hydrazine hydrate gave coumarin-3-acid hydrazide (2). 2 when treated with CS2/KOH yielded dithiocarbazate derivatives (3) which on treatment with hydrazine hydrate yielded triazole (4). 4 was reacted with various aromatic aldehydes to afford triazolo-thiadiazoles 5(a-j). The structures of the compounds 5(a-j) have been confirmed by IR, H-1 NMR & Mass spectral data. All the compounds have been screened for their antimicrobial, antifungal activity and antioxidant activity.