Molecules 2008, 13(8), 1846-1863; doi:10.3390/molecules13081846
Article

Oligomerization of Indole Derivatives with Incorporation of Thiols

Received: 10 June 2008; in revised form: 18 August 2008 / Accepted: 19 August 2008 / Published: 26 August 2008
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: Two molecules of indole derivative, e.g. indole-5-carboxylic acid, reacted with one molecule of thiol, e.g. 1,2-ethanedithiol, in the presence of trifluoroacetic acid to yield adducts such as 3-[2-(2-amino-5-carboxyphenyl)-1-(2-mercaptoethylthio)ethyl]-1Hindole-5-carboxylic acid. Parallel formation of dimers, such as 2,3-dihydro-1H,1'H-2,3'-biindole-5,5'-dicarboxylic acid and trimers, such as 3,3'-[2-(2-amino-5-carboxyphenyl) ethane-1,1-diyl]bis(1H-indole-5-carboxylic acid) of the indole derivatives was also observed. Reaction of a mixture of indole and indole-5-carboxylic acid with 2-phenylethanethiol proceeded in a regioselective way, affording 3-[2-(2-aminophenyl)-1-(phenethylthio)ethyl]-1H-indole-5-carboxylic acid. An additional product of this reaction was 3-[2-(2-aminophenyl)-1-(phenethylthio)ethyl]-2,3-dihydro-1H,1'H-2,3'-biindole-5'-carboxylic acid, which upon standing in DMSO-d6 solution gave 3-[2-(2-aminophenyl)-1-(phenethylthio)ethyl]-1H,1'H-2,3'-biindole-5'-carboxylic acid. Structures of all compounds were elucidated by NMR, and a mechanism for their formation was suggested.
Keywords: Side reaction; oligomerization of indole derivatives; incorporation of thiols; regioselectivity; NMR study
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MDPI and ACS Style

Mutulis, F.; Gogoll, A.; Mutule, I.; Yahorava, S.; Yahorau, A.; Liepinsh, E.; Wikberg, J.E. Oligomerization of Indole Derivatives with Incorporation of Thiols. Molecules 2008, 13, 1846-1863.

AMA Style

Mutulis F, Gogoll A, Mutule I, Yahorava S, Yahorau A, Liepinsh E, Wikberg JE. Oligomerization of Indole Derivatives with Incorporation of Thiols. Molecules. 2008; 13(8):1846-1863.

Chicago/Turabian Style

Mutulis, Felikss; Gogoll, Adolf; Mutule, Ilze; Yahorava, Sviatlana; Yahorau, Aleh; Liepinsh, Edvards; Wikberg, Jarl E. 2008. "Oligomerization of Indole Derivatives with Incorporation of Thiols." Molecules 13, no. 8: 1846-1863.

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