Bisindoles : synthesis and reactions

Abstract: In this thesis, synthesis of various bisindoles have beendeveloped.2,3-Bis-(3-indolyl) succinic acid derivatives wereobtained via iodine promoted coupling of the trianion ofindole-3-acetic acid (IAA) or from the dianion of themethylester of IAA. These compounds were converted to2,3-bis(3-indolyl) maleimides (arcyriarubin analogues) by DDQoxidation. Indolo[2,3-a]carbazoles were obtained by DDQ promoted cyclization/dehydrogenation orviaacid induced cyclization in TFA. Some of thesecompounds were obtained in an isomerically pure form and theirstructures were determined.Indolo[3,2-a]carbazoles were synthesized in one-step from indoleand various maleimides. The mechanism of the reaction isdiscussed.3,3’-Disubstituted 2,2’-biindolyls have beensynthesized from 2,2’-biindolyl by substitution reactionsand by dimerization of IAA and esters of IAA.2:2 Condensation products are obtained when2,2’-biindolyl is reacted with various benzaldehydes,forming ten-membered rings.A bisindole structure containing a cyclopentano ringfused to theb-face of one of the indoles is formed in an acidinduced dimerization/cyclization tandem reaction ofN-benzyl-3-(3-indolyl)maleimide.The synthetic concept which primarily have been utilizedin the synthesic work described here is acid induceddimerization and/or cyclization of an intermediate indoliumion.Keywords:bisindoles, acid-induceddimerization/cyclization, oxidative coupling, indolium ion,indolo[2,3-a]carbazole, indolo[3,2-a]carbazole, 2,2’-biindolyl.