Chemoselective reaction of benz[<i>g</i>]indole dicarboxylate towards hydrazine hydrate: Bisheterocycles: Synthesis and antimicrobial activity of some new 1-[2-hydroxyethyl]-3-ethoxycarbonyl-5-oxadiazolyl/triazolyl/ pyrrolylaminocarbonylmethoxy-2-methylbenz[<i>g</i>]indoles

Abstract

The exclusive formation of 1-[2-hydroxyethyl]-3-ethoxycarbonyl-2-methyl benz[<i>g</i>] indol-5-yloxyacetic acid hydrazide <b style="">6</b> from 1-[2-hydroxyethyl]-3-ethoxycarbonyl-5-methoxycarbonylmethoxy-2-methylbenz[<i>g</i>]indole <b style="">3 </b>revealed the chemo­selectivity of the C₅-ester over C₃-ester towards nucleophilic attack of hydrazine hydrate. This monocarbohydrazide <b style="">6</b> is reacted separately with CS₂/KOH, acetonyl acetone and isothiocyanates to secure the desired 1-[2-hydroxyethyl]-3-ethoxycarbonyl-5-(5-mercapto-1,3,4,-oxadiazl-2-y1)methoxy-2-methylbenz[<i>g</i>]indole <b style="">7</b>, 1-[2-hydroxyethyl]-3-ethoxy-carbonyl-5-(2,5-dimethylpyrrol-1-yl)aminocarbonylmethoxy-2-methylbenz[<i>g</i>]indole <b style="">8</b> and 1-[2-hydroxyethyl]-3-ethoxy­carbonyl-5-(<i>N</i>-substituted thiosemicarbazinocarbonyl)methoxy-2-methylbenz[<i>g</i>]indole <b style="">9a-c</b>. These thiosemicarbazides <b style="">9a-c</b> are reacted with 4% NaOH to produce the 1-[2-hydroxyethyl]2-methybenz[<i>g</i>]indol-5-(4-substituted-5-mercapto-1,2,4-triazol-3-yl)methoxy-3-caboxylic acids <b style="">10a-c</b>. All theses newly synthsised compounds are screened for their antimicrobial activities.