Synthesis and antimicrobial testing of some new S-substituted-thiopyridines, thienopyridines, pyridothienopyrimidines and pyridothienotriazines.

The reaction of 5-acetyl-4-aryl-3-cyano-6-methylpyridine-2(1H)-thiones (1a, b) with 4-methylphenacyl bromide, chloro-N-arylacetamides or chloroacetonitrile gave the corresponding S-substituted thiopyridines 2a-c, 4a-f and 6a-c, respectively. The latter compounds underwent intramolecular Thorpe-Ziegler cyclization to give 2-substituted 5-acetyl-3-amino-4-aryl-6-methylthieno[2,3-b]pyridines 3a-c, 5a-f and 7a-c. Compounds 5a-f and 7b, c are key intermediates in the synthesis of the target compounds. Some compounds showed remarkable antimicrobial activity.

Fluorine-containing heterocycles: synthesis and some reactions of new 3-amino-2-functionalized-6-(2'-thienyl)-4-trifluoromethylthieno [2,3-b]pyridines.

3-Cyano-6-(2'-thienyl)-4-trifluoromethylpyridine-2(1H)-thione (2) was prepared and reacted with chloroacetone or phenacyl bromide to yield the 2-acetyl or benzoyl-3-amino-6-(2'-thienyl)-4-trifluoromethylthieno[2,3-b]pyridines (3a, b). In contrast, the reaction of 2 with chloroacetamide or its N-aryl derivatives gave the corresponding 2-carbamoylmethyl thiopyridines 4a-c. Upon treatment of these educts with K2CO3 or C2H5ONa in ethanol, they underwent intramolecular Thorpe-Ziegler cyclization to afford 3-amino-2-carbamoyl-6-(2'-thienyl)-4-trifluoromethyl-thieno[2,3-b]pyridine (5a) and its N-aryl analogs 5b, c. Compounds 5a-c underwent some reactions to yield new pyrido[3',2':4,5]thieno[3,2-d]pyrimidines and pyrido[3',2':4,5]thieno[3,2-d][1,2,3] triazines.

Synthesis, reactions and antimicrobial activity of new cyclopenta[e]thieno[2,3-b]pyridines and related heterocyclic systems.

Reaction of the arylidene cyanothioacetamides 1a, b with cyclopentanone was proved to give a mixture of 4-aryl-3-cyanocyclopenta[b]pyridine-2(1H)-thiones 2a, b and the corresponding 7-arylidene derivatives 3a, b. Compounds 2a, b were reacted with ethyl chloroacetate or chloroacetamide to give the promising S-substituted thiopyridines 6a-d. On treatment of the latter compounds with sodium ethoxide in boiling ethanol, they underwent intramolecular Thorpe-Ziegler cyclization to yield the corresponding 3-amino-4-aryl-2-functionalized-cyclopenta[e]thieno[2,3-b]pyridines (7a-d). Most of these thienopyridines were reacted with a variety of reagents to produce other new cyclopentathienopyridines as well as numerous of their condensed heterocyclic derivatives. Some of the compounds synthesized were tested in vitro for their antibacterial and antifungal activity.

Synthesis, reactions and biological activity of some new thieno[2,3-f]-1,3-benzodioxoles.

The reaction of 7-chlorothieno[2,3-f]-1,3-benzodioxole-6-carbonyl chloride (2) with some aromatic or heterocyclic amines gave the corresponding 6-(aryl or heterocyclyl) carbamoyl-7-chlorothieno [2,3-f]-1,3-benzodioxoles (3a-c, 4a, b and 5). Compound 2 was also reacted with potassium thiocyanate, ethanol or sodium azide to afford the isothiocyanto compound 6, the ester 7 and the acid azide 9, respectively. Hydrazinolysis of 7 gave the carbohydrazide 8. The compounds 6, 8 and 9 were used as precursors in the synthesis of the target heterocycles, 7-chlorothieno[2,3-f]-1,3-benzodioxoles substituted with a variety of moieties at position-6 (10-15, 17, 19-26, 28-31). Also, 2-methyl-1,3-dixolo[5,6][1]benzothieno[2,3-c]quinolin- 6(5 H)-one (33) was prepared. The antibacterial and antifungal activities of some selected compounds were also reported.

Synthesis and biological screening of new 1,3-diphenylpyrazoles with different heterocyclic moieties at position-4.

1,3-Diphenyl-1 H-pyrazole-4-carboxaldehyde (1) was reacted with barbituric acid, thiobarbituric acid, some activated nitriles and/or acetophenone to give the condensation products 2a, b, 3a-c and 4, respectively. The reaction of 1 with hydrazine hydrate, semicarbazide or thiosemicarbazide afforded the corresponding azomethines 5a-c. The compounds 3a, b, 4 and 5a, c were subjected for different sequence reactions to produce the title compounds. The antibacterial and antifungal activity of some selected derivatives were evaluated.

Synthesis and antimicrobial activities of some new pyrrolylthieno[2,3-b]-quinoline derivatives.

2-Acetyl-4-(p-chlorophenyl)-3-(1-pyrrolyl)-5,6,7,8- tetrahydrothieno[2,3-b]quinoline (4a) and its corresponding 2-carbohydrazide derivative 5 were prepared and used as key intermediates in the synthesis of the title compounds. Some of the synthesized compounds were screened for their antibacterial and antifungal activities.

s-triazole systems. Part IV: Novel substituted thio-s-triazole derivatives.

Interaction of (3-aryloxymethyl-4-phenyl-s-triazol-5-yl)thioacethydrazid e (1a-c) with phenyl isocyanate and/or with methyl/phenyl isothiocyanate gave semicarbazides (2a-c) and thiosemicarbazides (3a-f) respectively. Cyclization of (3a-f) yielded s-triazoles (4a-f). Compounds 4b,d,f were easily alkylated giving S-substituted thio-s-triazoles (5a-e). Furthermore, compounds 4b,d,f underwent a Mannich reaction to give the expected Mannich bases (6a-f). All compounds were fully confirmed by elemental and spectral analyses and have been screened in vitro for antimicrobial activity.