STUDIES ON THIAZOLOPYRIDINES. PART 2. SYNTHESIS AND ANTIMICROBIAL ACTIVITY OF NOVEL  THIAZOLO[3,2a] PYRIDINE AND THIAZOLO[3,2 a] [1,8] NAPHTHYRIDINE DERIVATIVES HAVING TWO DIFFERENT ARYL MOIETIES

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[3,2a]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[2,3d]pyrimidines 8ac. 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.