Synthesis and Antimicrobial Activity of New 2,5-Disubstituted 1,3,4-Oxadiazoles and 1,2,4-Triazoles and Their Sugar Derivatives

A series of new 2,5-disubstituted-l,3,4-oxadiazole and 1,2,4-triazole derivatives were synthesized by hetero- cyclization of acid hydrazide I and thiosemicarbazide derivative 2. Furthermore, the acyclic C-nucleoside analogs were prepared by cyclization of their corresponding sugar hydrazones by reaction with acetic anhydride. The antimicrobial activity of the prepared compounds was evaluated and some of the synthesized compounds revealed good activities against fungi.

Synthesis of ribonucleoside analogues containing thio-substituted 1,3,4-triazole as heterocyclic base

New ribonucleoside analogues containing thio-substituted 1,3,4-triazole as heterocyclic base have been synthesized via condensation of the central intermediate 1 with various acids, esters, amides, and anhydrides in anhydrous solvent followed by deprotection.

Structure and Biological Activities of Novel Triazole Compounds Containing 1,3,4-Oxadiazole Ring

Eighteen novel triazole compounds containing 1,3,4-oxadiazole groups were synthesized from 2-（1H-1,2,4-triazol-1-yl）acetohydrazide and carbon disulfide by several step reactions. The target compounds were characterized by elemental analysis, 1H NMR, 13C NMR, IR, MS, and X-ray crystallography. The results of preliminary biological tests show that all the compounds exhibit certain fungicidal activities.

Synthesis of heierocyclic compounds from 2-phenyl-1, 2,3-triazole-4-formylhydrazine

2-Phenyl-1, 2, 3-triazole-4-formylhydrazine (2) was prepared by hydrazinolysis of the corresponding ester 1. Reaction of 2 with CS2/KOH gave the oxadiazole derivatives (3) which via, Mannich reaction with different dialkyl amines furnished 3-N, N-dialkyl derivatives (4a-c). Also, condensation of 2 with appropriate aromatic acid in POCl3 yielded oxadiazole derivatives (5a-c), or with aldehydes and ketones afforded hydrazones (6a-c). Cyclization of (6a-c) with acetic anhydride gave the desired dihydroxadiazole derivatives (7a-c). On the other hand, reaction of dithiocarbazate (8) with hydrazine hydrate gave the corresponding triazole derivative (9) which on treatment with carboxylic acids in refluxing POCl3 yielded s-triazole[3,4-b]-1, 3, 4-thiadiazole derivatives (10a-b). The structures of all the above compounds were confirmed by means of IR, 1H NMR, MS and elemental analysis.

Triheterocyclic Thiadiazepine Derivatives of Pharmacological Interest： Synthesis of 2-Aryl-4-[ρ-（2,3-dihydro-5-methyl-2-oxo-1,3,4-oxadiazol-3-yl）phenyl]-6-（u n）su bstituent-1 ＂,2＂ ,4＂- triazolo[3＂,4＂-b]-1 ＇,3＇,4＇-thiadiazepine

Synthesis of novel thiadiazepine derivatives based on the reactivity of 4-acetylphenylsydnone （1） was reported. The structures of the newly synthesized compounds have been proved by their physical, analytical, IR, 1^H NMR, 13^C NMR and mass spectral data.

Synthesis and Antimicrobial Activity of Some Condensed [4-（2,4,6-Trimethylphenyl）-1 （2H）-oxo-phthalazin-2-yl]acetic Acid Hydrazide

Some new 1,2,4-triazolo-, 1,3,4-oxadiazolo-, 1,3,4-thiadiazol-, and pyrazolo-2,4,6-trimethylphenyl-1（2H）-oxo- phthalazine derivatives were synthesized and identified by IR, ^1H NMR, ^13C NMR, MS and elemental analysis. The new compounds were synthesized with the objective of studying their antimicrobial activity.

Synthesis of some heteroaryl pyrazole derivatives and their biological activities

In order to search for novel fungicides with high activity, a series of heteroaryl pyrazoles were synthesized from 5-pyrazole formhydrazide. The structures of all new compounds were confirmed by spectroscopic methods and microanalyses. Preliminary bioassays indicated that some compounds showed fungicidal activity against Puccinia tritinia and PGR activity as well.