Ahmed A. El-Maghraby

Studies of Thiazolopyridines, Part 6: Synthesis and Antimicrobial Evaluation of Some Novel Thiazolo[3,2-a] Pyridine and Thiazolo[2′,3′:6,1]-pyrido[2,3-d]pyrimidine Derivatives

Condensation of thiazolinone 1 with aromatic aldehydes yielded the corresponding methylidene derivatives 2a–f. Cyclization of compounds 2a–f with arylidenemalononitrile 3 (1:1 molar ratio) in ethanol in the presence of piperidine furnished the novel thiazolo[3,2-a]pyridines 5a–v, via Michael adduct 4. Compounds 5p, r were cyclized with malononitrile in the presence of piperidine to yield thiazolo[3,2-a][1,8]naphthryidines 7a, b. Thiazolo-[2′,3′:1,6]pyrido[2,3-d]pyrimidine 9a–cwere obtained by cyclization of compounds 5c, p, r with formic acid. The structure of the synthesized compounds was established by analytical and spectral data. Also, some of the synthesized compounds were screened for antimicrobial activity in vitro.

STUDIES ON THIAZOLOPYRIDINES. PART 5: SYNTHESIS OF HITHERTO UNKNOWN THIAZOLINONE AND THIAZOLO[3,2-a]PYRIDINE DERIVATIVES HAVING IN THEIR STRUCTURE THE MORPHOLIN-4-YL MOIETY

Condensation of thiazolinone 1 with benzaldehydes 2a, b in ethanolic piperidine afforded the methylidene derivatives 3a, b. Cyclocondensation of compound 3b with malononitrile furnished the novel thiazolo[3,2-a]-pyridine 5. Also, compound 3b was condensed with dimethylformamide-dimethylacetal (DMF-DMA) and triethylortho-formate to yield N,N-dimethylamino 6 and ethoxymethylene 7 derivatives respectively. The novel thiazolo[3,2-a]pyridines 10a, b were obtained by cyclocondensation of compounds 3a, b with benzylidene-malononitriles 8a, b. Similarly, cyclocondensation of compound 3b with benzylidenemalononitrile 11 afforded the thiazolopyridines 12a–c. Ternary condensation of compound (12), 4-morpholinobenzaldehyde 2b and malononitrile (1:1:1 molar ratio) produced the thiazolopyridines 14a–c. When compound 10b was subjected to react with malononitrile in dioxane/piperidine under reflux the novel condensed heterocyclic system 18 was obtained. Treatment of ortho-aminocarbonitrile 10b with formic acid, aromatic aldehyde and triethylorthoformate furnished the thiazolo[2′,3′:1,6] pyrido[2,3-d] pyrimidine 20, azomethine 21a, b and ethoxymethylene 22 derivatives respectively. The structure of the synthesized compounds was established by analytical and spectral data.

Heteroaromatization with Sulfonamido Phenyl Ethanone, Part I: Synthesis of Novel Pyrrolo[2,3-D]Pyrimidine and Pyrrolo[3,2-E][1,2,4]Triazolo[1,5-C]Pyrimidine Derivatives Containing Dimethylsulfonamide Moiety

4-(5-Amino-4-cyano-1-p-tolyl-1H-pyrrol-3-yl)-N,N-dimethyl-benzenesulfonamide (4) was prepared and converted to several pyrrolo[2,3-d]pyrimidin-5-yl)-N,N-dimethyl-benzenesulfonamide derivatives (5,7,9, and 13). Cyclocondensation of 13 with different electrophilic carbon reagents afforded several 4-(N,N-dimethylaminosulfonylphenyl)]pyrrolo[3,2-e][1,2,4]triazolo[1,5-c]-pyrimidine derivatives (14–17,19, and 20); IR, 1HNMR, and mass spectra of the newly synthesized compounds were recorded. Most of the obtained compounds were screened against Gram-positive and Gram-negative bacteria and fungi, for which some of these derivatives gave promising results.

Studies on Thiazolopyridines. Part 4: Synthesis of Hitherto Unknown 1,4-Bis(thiazolopyridine)benzene Derivatives

2-Cyanomethyl-4-thiazolinone ( 1 ) was condensed with terephthalaldehyde ( 2 ) (2:1 molar ratio) and produced 1,4-bis(2-cyanomethyl-4,5-dihydro-5-methylidene-4-thiazolinone-5-yl) benzene ( 3 ). Treatment of compound ( 3 ) with benzylidenemalononitrile ( 4 ) (1:2 molar ratio) furnished the novel bisthiazolopyridines ( 6a-e ). Condensation of compound ( 1 ) with aromatic aldehyde yielded the benzylidene derivatives ( 7a-f ), which on treatment with compound ( 8 ) (2:1 molar ratio) afforded the novel bisthiazolopyridines ( 10a-f ). Structures of the synthesized compounds have been established by elemental analyses and spectral data.

Heteroaromatization with Sulfonamido Phenyl Ethanone, Part II: Synthesis of Novel Thiazolyl Acetonitriles and Thiazolyl Acrylonitriles and Their Derivatives Containing Dimethylsulfonamide Moiety

Thiazolyl acetonitrile (2) was prepared and converted to pyrazolo[5,1-c][1,2,4]triazine (5), thiazoline-4-one derivatives (10,12), thiazolo[3,2-a]pyridine (13), coumarin (14), and benzo[f]coumarin (16) derivatives through reactions with a variety of organic electrophiles and nucleophiles. Thiazolyl acrylonitrile derivatives (17, 18, 21, 26–28, 31–33) were also prepared, and their activity with a variety of reagents was investigated. The structure of these compounds was elucidated on the basis of elemental analysis, IR, 1H-NMR, and mass spectra. The antimicrobial and antifungal activities of the prepared compounds are also reported.

Preparation of new derivatives of thiazole, thiazolidine, and thiazol-2-ylpyrazolo[3,4-d]pyrimidine sulfonamido conjugates

Several new thiazoles ( 3–7 ), thiazolylpyrazole carbonitrile ( 10 , 11 ), and Thiazolidine sulfonamido conjugate derivatives ( 19–26 ) were prepared starting with p-Piperidinesulfonylacetophenones ( 1 , 2 ). The structure of these compounds was elucidated on the bases of elemental analysis, IR, PMR, and mass spectra. The antimicrobial activities of some selected compounds are also reported.