Abstract
In this paper the synthesis of some substituted 1,3,4-oxadiazoles , 1,3,4-thiadiazoles and 1,2,4-triazoles starting from amino acid and benzoyl chloride is reported. Treatment of glycine or alanine with benzoyl chloride in presence of sodium carbonate gave keto-acid(1,2), which were converted to oxazolinone (3,4) by their reaction with acetic anhydride. Oxazolinone (3,4) were treated with hydrazine hydrate to give acid hydrazides (5,6). Acid hydrazides were converted to substituted thiosemi- carbazides (7,8) by their reaction with phenyl isothiocyanate. Substituted thiosemicarbazides (7,8) were treated with sodium hydroxide and concentrated sulphuric acid give substituted 1,2,4-triazoles (9,10), 1,3,4-thiadiazoles (11,12) respectively while treatment of (7) with mercuric oxide gave 1,3,4-oxadiazoles (13). Treatment of triazoles (9,10) with 4-hydroxybenzaldehyde gave substituted triazoles (14,15). 1-Substituted thiosemicarbazide (16) was obtained from acid hydrazide (5), cyclized with sodium hydroxide to 5-Substituted-1,2,4-triazole-3-thiol (17). The structures of the synthesized compounds were confirmed by physical and spectral means.
Highlights
Five membered ring heterocyclic 1,3,4-oxadiazoles, 1,3,4thiadiazole and 1,2,4-triazoles and their derivatives are considered as an important class of compounds because of their diversified biological applications(1). 1,3,4-oxadiazole derivatives showed antibacterial(2,3), antiinflammatory(4), antitubercular(5), anticonvulsant(6), antimalarial(7) and antifungal agents(8).1,3,4-thiadiazole exhibit various biological activities as anticancer(9), anticonvulsant(10),antibacterial(11),anti-inflammatory(12) and antifungicidal(13). 1,2,4-triazole derivatives showed biological effects, such as antifungal(14), anticancer(15), antibacterial(16), anticonvulsant(17) and anti-inflammatory(18)
The synthesis of substituted 1,3,4-oxadiazoles was achieved by condensation of acyl hydrazine with acetic acid in phosphorous oxychloride to give 2,5-disubstituted 1,3,4-oxadiazole(19). 2Substituted 1,3,4-oxadiazole were synthesized from acid hydrazides by their reaction with carbon disulfide in ethanolic potassium hydroxide20,21). 1,3,4-oxadiazoles were synthesized by cyclization of substituted thiosemicarbazide by phosphoric acid(22), concentrated sulphuric acid(23) or methyl sulfonate(24). 1,3,4-Thiadiazoles (I) and (II) were synthesized from substituted thiosemicarbazide by phosphoric acid(22) and concentrated sulphuric acid(25) respectively
1,2,4-Triazole derivatives were synthesized from thiosemicarbazides by their reaction with sodium hydroxide solution as compound (III)(26). 5alkyl-1,2,4-triazole-3-thiol was treated with alkyl halides to give alkylthio derivative (IV)(27)
Summary
Five membered ring heterocyclic 1,3,4-oxadiazoles, 1,3,4thiadiazole and 1,2,4-triazoles and their derivatives are considered as an important class of compounds because of their diversified biological applications(1). 1,3,4-oxadiazole derivatives showed antibacterial(2,3), antiinflammatory(4), antitubercular(5), anticonvulsant(6), antimalarial(7) and antifungal agents(8). Five membered ring heterocyclic 1,3,4-oxadiazoles, 1,3,4thiadiazole and 1,2,4-triazoles and their derivatives are considered as an important class of compounds because of their diversified biological applications(1). 1,3,4-oxadiazole derivatives showed antibacterial(2,3), antiinflammatory(4), antitubercular(5), anticonvulsant(6), antimalarial(7) and antifungal agents(8). 1,3,4-thiadiazole exhibit various biological activities as anticancer(9), anticonvulsant(10),antibacterial(11),anti-inflammatory(12) and antifungicidal(13). 1,2,4-triazole derivatives showed biological effects, such as antifungal(14), anticancer(15), antibacterial(16), anticonvulsant(17) and anti-inflammatory(18). The synthesis of substituted 1,3,4-oxadiazoles was achieved by condensation of acyl hydrazine with acetic acid in phosphorous oxychloride to give 2,5-disubstituted 1,3,4-oxadiazole(19). 1,3,4-oxadiazoles were synthesized by cyclization of substituted thiosemicarbazide by phosphoric acid(22), concentrated sulphuric acid(23) or methyl sulfonate(24). 1,3,4-Thiadiazoles (I) and (II) were synthesized from substituted thiosemicarbazide by phosphoric acid(22) and concentrated sulphuric acid(25) respectively The synthesis of substituted 1,3,4-oxadiazoles was achieved by condensation of acyl hydrazine with acetic acid in phosphorous oxychloride to give 2,5-disubstituted 1,3,4-oxadiazole(19). 2Substituted 1,3,4-oxadiazole were synthesized from acid hydrazides by their reaction with carbon disulfide in ethanolic potassium hydroxide20,21). 1,3,4-oxadiazoles were synthesized by cyclization of substituted thiosemicarbazide by phosphoric acid(22), concentrated sulphuric acid(23) or methyl sulfonate(24). 1,3,4-Thiadiazoles (I) and (II) were synthesized from substituted thiosemicarbazide by phosphoric acid(22) and concentrated sulphuric acid(25) respectively
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