Synthesis of oxadiazole-thiadiazole fluorochromane hybrids and their antioxidant activity

In this study, we set out to create some new oxadiazole-thiadiazole fluorochromane hybrid compounds 7a-7j and test them for their antioxidant properties. & beta;-blockers drug-based 6-fluorochromane-2-carboxylic acid 1 was used as starting material and was cyclized to 1,3,4-thiadiazole 2 using POCl3 media. Acylation of the amino group of oxadiazole using chloroacetyl chloride yielded the acylated compound 3. The 1,3,4-oxadiazoles 6a-6j were prepared from acid hydrazides on reaction with CS2 in NaOH. A K2CO3 catalyzed coupling of N-acetylated amino-oxadiazole 3 with 1,3,4-oxadiazoles 6a-6j led to the formation of hybrids 7a-7j linked through the amidic bridge. Antioxidant activity (as IC50) was measured for all compounds using ascorbic acid (781.32 & mu;M) as the reference and found that most showed higher potency when compared with the standard. among those, compounds 7c (399.57 & mu;M), 7d (551.85 & mu;M), 7e (565.71 & mu;M), and 7 h (574.48 & mu;M) with isomeric nitro (2-NO2, 4NO2) and fluoro (4-F, 4-CF3) as substituents showed significant activity. The structures of all compounds were proven by mass spectrometry, IR, and NMR spectroscopies.