G. A. M. El-Hag Ali, A. H. A. Ahmed
Chemistry Department, Faculty of Science, Al – Azhar universitY, Nasr City, Cairo, Egypt.

A. Khalil,
Chemistry Department, Faculty of Science, Ain Shams university, Cairo, Egypt.

M. S. A. El-Gaby
Chemistry Department, Faculty of Science, Al -Azhar university, at Assuit, Assuit 71524 , Egypt.
 

Abstract
Condensation of thiazolinone 1 with aromatic aldehydes in ethanol / piperidine solution furnished the novel thiazolidinone derivatives 2a-e. Ternary condensation of 2, malononitrile and aromatic aldehydes (1: 1: 1 molar ratio) in absolute ethanol containing a catalytic amount of piperidine yielded the thiazolo[3,2–a]pyridines 3a-h in good yields. Thiazolo[3,2 – a][1,8]naphthyridines 6a-c were obtained by treatment of  3a, d,h with malononitrile in ethanol in the presence of piperidine as a basic catalyst. Refluxing of compounds 3b, g, h in formic acid furnished the novel thiazolo[2`,3`:1,6] pyrido[2,3–d]pyrimidines 8a–c. Interaction of 8c with malononitrile in ethanol / piperidine solution produced the pyrano[2`,3`:4,5]thiazolo[3`,2:1,6]pyrido[2,3-d]pyrimidine 9. Structures of the synthesized compounds have been established by elemental analyses and spectral data. Compounds 3a-h, 6a-c and 8a-c have been screened for antimicrobial activity.