SYNTHESIS, CHARACTERIZATION, ANTICANCER, ANALGESIC, AND ANTIINFLAMMATORY ACTIVITIES OF HITHERTO UNKNOWN THIAZOLO[3,2-A] PYRIDINE AND THIAZOLO [3,2-A] 1,8-NAPHTHYRIDINE DERIVATIVES

Ethyl-5-(arylmethylene)-4-oxothiazolidin-2-ylidene)acetate (2)was synthesized by refluxing of 2,4- dichlorobenzaldehyde with 4- thiazolidinone derivative (1) which further underwent cyclization with different α-substituted cinnamonitriles to afford thiazolo [3,2-a] pyridines (3,4,5)a-e , respectively. Reaction of 3a with Ac2O gave the corresponding N-acetyl amino thiazolo[3,2- a]pyridine (6), together with 1,8-naphthyridine derivative (7) depending on the time of the reflux . Also ,treatment of 3a with HCO2H and/or p-chlorobenzoyl chloride gave the corresponding 1,8- naphthyridine derivatives (8,9),respectively. Thi-azolo[3,2a] pyridine (3a), reacted with chloroacetonitrile to give amidine derivative (10) , while upon treatment with malononitrile undergoes concerted addition to give the corresponding thiazolo [3,2-a] 1,8-naphthyridine derivative (11), Also, 3a reacted with ethylisothiocyanate to afford the corresponding thiourea derivative (12).Finally;Where 3a refluxed with hydrazines (as binucleophile) in ethanol and gave pyrazolo [3',4'?4,5] thiazolo [3,2-a] pyridine derivatives (13a-c), through cyclocondensation and oxidation reactions with α-β unsaturated carbonyl system