Azoniaallene salts as versatile building blocks in the synthesis of antibacterial and antifungal heterocyclic compounds

Abstract

Substituted 2-azoniaallene salts 1 are strong bifunctional electrophiles, undergo cyclization reactions furnish many series of heterocyclic compounds, where reacted with p-tolyl urea, phenyl thiourea and thiosemicarbazone derivatives to afford triazinium salts, and converted to corresponding free bases 3, 5, 7 under treatment with Na 2 CO 3 . While triazole derivatives 8 and 9 were obtained by the reaction 2-azoniaallene salts 1 with benzohydrazide and phenyl hydrazine, respectively. Benzoxazinium salts 10 and 11 were acquired when asymmetric 2-azoniaallene salt reacted in (1:1) ratio with p-cresol and 3-methyl-1-phenyl-5-pyrazolone, respectively. The reaction of 2-azoniaallene salt with malononitrile furnished the primidinium salt 12 which underwent neutralization with Na 2 CO 3 followed by heterocyclization with hydrazine hydrate afforded the bicyclic compound 3-aminopyrazolo[3,4-d]pyrimidine 14, which is highly reactive for nucleophilic addition to phenyl isothiocyanate to furnish thiourea derivative 15. Moreover, 14 undergo condensation with aldehydes to give imine derivatives 16a,b. All free base compounds were screened for their antimicrobial activities.