Synthesis and Biological Activities of Some New 3h-Quinazolin-4-One Derivatives Derived From 3-Phenylamino- 2-Thioxo-3h-Quinazolin-4-One

Reaction of 3-phenylamino-2-thioxo-3H-quinazolin-4-one (1) with methyl iodide, α-chloroethylacetate, and α-bromobenzoylacetophenone in methanol in the presence of KOH with heating resulted in alkylation on the sulfur atom to 2-alkyl thio derivatives 2–4, respectively. Treatment of 1 with α-bromo-α-cyanoethylacetate afforded 3-hydroxy-10-oxo-4-phenyl-4H,10H-1-thia-4,4a,9-triaza-anthrancene-2-carbonitrile (5). Reaction of the ester 3 with hydrazine hydrate afforded hydrazide 6. The hydrazide 6 on reaction with benzoylacetone, dibenzoylmethane, and ethyl acetoacetate furnished the corresponding pyrazoles 7 and 8 and pyrazolone 9 respectively. Treatment of 6 with methanolic KOH and carbon disulphide afforded 1,3,4-oxadiazole-2-thione derivative 10. Compound 1 reacted namely with 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosylbromide, 2,3,4,6-tetra-O-acetyl-α-D-galactopyranosyl bromide, or with 2,3,4-tri-O-acetyl-α-D-xylopyranosyl bromide to yield S-glycoside derivatives 11–13, respectively. Oxidation of S-glucoside 11 with H 2 O 2 afforded the corresponding sulphone; 2-(2′,3′,4′,6′-tetra-O-acetyl-β-D-glucopyranosylsulphonyl)-3-phenlyamino-3H-quinazolin-4-one (14). The synthesized compounds have been screened for their antimicrobial activity.