Chemoselectivity of bisindole tetracarboxylate towards hydrazine hydrate:Synthesis and antimicrobial activity of diethyl 5,5'-bis(2,5-dimethylpyrrol-1-ylaminocarbonylmethoxy)-2,2' -dimethyl-1, l' -(ethane-1,2-diyl)di(1<i>H</i>-indole )-3,3'-dicarboxylate

Abstract

Diethyl 5,5' -dihydroxy-2,2'-dimethyl-1,1' -(ethane-1,2-diyl)di(1H-indole)-3,3'-dicarboxylate <b>3</b> has been prepared in one-flask procedure by the condensation of diethyl 3,3'-(ethane-2,2' -diyldiimino )butenoate <b>1</b> with 1,4-benzoquinone <b>2</b> in 1:2 molar ratio. Reaction of <b>3</b> separately with methyliodide and ethyl chloroacetate affords the corresponding <i>O</i>-alkylated derivatives <b>4</b> and <b>5,</b> respectively. Exclusive formation of diethyl 5,5'-bi-(hydrazinocarbonylmethoxy)-2,2' -dimethyl-1,1'(ethane-1,2-diyl)di(1<i>H</i>-indole)-3,3'-dicarboxylate <b>6</b> from <b>5</b> reveals the chemoselectivity of 5,5'-ester function towards nucleophilic attack of hydrazine hydrate. This dicarbohydrazide <b>6</b> on reacting with acetonylacetone furnishes diethyl 5,5-<i>'</i>bis(2,5-dimethylpyrrol-l-ylamino-carbonylmethoxy)-2,2' -dimethyl-1,1'-(ethane-1,2-diyl)di(1H-indo le)-3,3'-dicarboxylate <b>8</b>.Conformations of all these bisindole derivatives have been established. Compounds <b>3, 4, 5, 6</b> and <b>8</b> have also been screened for their antibacterial and antifungal activities.