Katsuhiro Hosoya

Polymerisation of indole. Part 2. A new indole trimer

Treatment of indole (1) with toluene-p-sulphonic acid in benzene provided the 2,3′-indole trimer (4), a positional isomer of the well known 3,3′-indole trimer (3). The structure of the new trimer (4) was established by comparative studies with the trimers (3) and (4).

Fischer indolization and its related compounds—VII : Development of abnormal fischer indolization of ortho-methoxyphenylhydrazone to provide a synthetic method for useful indole derivatives possessing an active methine group at C6 and novel 3,6′-biindole derivatives☆☆☆

Abstract Fischer indolization of ethyl pyruvate 2-methoxyphenylhydrazone ( 1 ) with p -toluene-sulfonic acid in benzene in the presence of an enolizable dicarbonyl or an indolic compound gave either an indole product having an active methine group at C 6 or a novel type of 3,6′-biindole compound. Structures of the products were established by NMR spectra and chemical evidence.