Chemoselective reaction of benz(<i>g</i>)indole based bisheterocycle dicarboxylate towards hydrazine hydrate: Synthesis and antimicrobial activity of new triheterocycles-5-pyrrolylaminocarbonyl/ mercaptooxadiazolyl/4-allyl-5-mercaptotriazolylmethoxy-1-furfuryl-2-methylbenz(<i>g</i>)indoles

1470-1475Chemoselectivity of C5-ester over that of C3-ester function of the benz(g)indole based bisheterocycle dicarboxylate towards the nucleophilic attack of hydrazine hydrate has been evidenced by the exclusive formation of 1-furfuryl-3-ethoxycarbonyl-5-hydroxy-2-methylbenz(g)indole-5-yloxyacetic acid hydrazide 5 which is reacted separately with acetonyl acetone, carbon disulphide in boiling ethanolic potassium hydroxide and allyl isothiocyanate to produce respectively 1-furfuryl-3-ethoxycarbonyl-5-(2,5-dimethylpyrrol-1-yl)aminocarbonylmethoxy-2-methylbenz(g)indole 7, 1-furfuryl-3-ethoxy-carbonyl-5-(5-mercapto-1,3,4-oxadiazol-2-yl)methoxy-2-methylbenz(g) indole 8, and 1-furfuryl-3-ethoxycarbonyl-5-(N-allylthiosemicarbazinocarbonyl)methoxy-2-methylbenz(g)indole 9. The thiosemicarbazide 9 when heated with 4% NaOH undergoes cyclisation with concomitant hydrolysis of C3-ester group to yield 1-fufuryl-5-(4-allyl-5-mercapto-1,2,4-triazol-3-yl)methoxy-2-methylbenz(g)indole-3-carboxylic acid 10. The structures of newly synthesized compounds are confirmed on the basis of their spectral and analytical data and the compounds are also screened for their antibacterial and antifungal activities