Synthesis and Antibacterial Activity of Novel (4-Methoxyphenyl)-tetrahydropyranyl-substituted 1,3,4-Oxadiazoles

Condensation of 4-(4-methoxyphenyl)tetrahydro-2H-pyran-4-carbonyl chloride with hydrazine hydrate, furan-2- and 2,5-dimethylfuran-2carbohydrazides gave disubstituted hydrazides, whose cyclization formed symmetrical and unsymmetrical 2,5-disubstituted 1,3,4-oxadiazoles. Ethyl 4-[4-(4-methoxyphenyl)-tetrahydro-2H-pyran-4-carboxamido]benzoate was reacted with hydrazine to obtain N-[4-(hydrazinocarbonyl)-phenyl]-4-(4-methoxphenyl)tetrahydro-2H-pyran-4-carboxamide. Treatment of the latter with triethyl orthoformate gave a monosubstituted 1,3,4-oxadiazole, and with carbon disulfide, a 5-sulfanyl-1,3,4-oxadiazole derivative was obtained. The subsequent alkylation of this derivative with 5-metoxyfuran-2-methyl and benzylaminocarbonylmethyl chlorides substituted chlorides resulted in the synthesis of the corresponding novel S-substituted oxadiazole derivatives. The synthesized compounds were tested for antibacterial activity.