Novel Synthesis of Pyrano[2,3-d]Thiazole, Thiazolo[3,2-a]Pyridine, and Pyrazolo [3',4':4,5] Thiazolo[3,2-a]Pyridine Derivatives

Author: El-Hag Ali G.A. M.   Abd El-Rahman M.T.   Helal M. H. M.   El-Gaby M. S. A.  

Publisher: Taylor & Francis Ltd

ISSN: 1042-6507

Source: Phosphorus, Sulfur, and Silicon and the Related Elements, Vol.183, Iss.12, 2008-12, pp. : 3023-3036

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Abstract

Cyclocondensation of 2-cyanomethyl-4-thiazolidinone (1) with tetracyanoethylene (2) furnished pyrano[2,3-d]thiazole derivative (4). Benzo[e]pyrano[2,3-d]thiazole derivative (6) was obtained by cyclization of compound (1) with salicylaldehyde. In a similar manner, condensation of compound (1) with 2-hydroxy-1-naphthaldehyde in refluxing ethanol yielded naphtho[e]pyrano[2,3-d]thiazole derivative (7). Interaction of compound (9) with benzylidenemalononitriles (10) (1 : 1 molar ratio) at reflux temperature in ethanol in the presence of piperidine afforded thiazolo[3,2-a]pyridines (12a-c). Treatment of compound (12a) with hydrazines furnished pyrazolo[3',4':4,5] thiazolo[3,2-a]pyridines (14a,b). The reaction of compound (1) with benzyli-denecyanoacetate (16) yielded 5-hydroxythiazolo[3,2-a]pyridine derivative (21). Cyclization of bis(thiazolinone) (23) with benzylidenemalononitriles (10) produced bis(thiazolopyridine) derivatives (25a,b).

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