The synthesis of 3-[beta]-aminoethylindole / by Arthur James Ewins.

  • Ewins, Arthur James.
Date:
1911
Catalogue details

Licence: In copyright

Credit: The synthesis of 3-[beta]-aminoethylindole / by Arthur James Ewins. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    mann and Kutscher, Zeit&cli. Biol., 1910, 54, 387; Barger and Dale, Trans., 1910. 97, 2592; Dale and Laidlaw, J. Physiol., 1910, 41, 318). Of the amino-acids known to occur in proteins for which the corresponding amine remained unknown, tryptophan is the most important. This amino-acid was first isolated by Hopkins and Cole (./. Physiol., 1901-1902, 27. 418), and afterwards synthesised by Ellinger and Flamand (Her., 1907, 40. 3029). The amine derived from this amino-acid has now been obtained both synthetically and by the action of putrefactive bacteria on tryptophan itself (Ewins and Laidlaw. Proc., 1910, 26, 343), and the method of synthesis forms the subject of the present communication. (The action of putrefactive bacteria on tryptophan had previously been studied, but the isolation of the base was achieved only when its synthesis had revealed the properties of the amine.) It was at first hoped that by heating tryptophan under very greatly diminished pressure, carbon dioxide might be split off, as in the case of tyrosine. This experiment was carried out at Dr. G. Barger s suggestion but the only product that could be isolated from the sublimate was a very small quantity of unchanged tryptophan. The method employed by Windaus and Vogt (lor. rit.) in the synthesis of 4-0-aminoethylglyoxaline from /3-glyoxaline- 4-propionic acid derived from histidine cannot here be employed, owing to the action of nitrous acid on the indole nucleus. The method ultimately adopted was a modification of Fischer’s method of synthesising indole derivatives, in which the phenyl- hydrazone of the suitable aldehyde is heated with zinc chloride. In this instance, the requisite aldehyde cannot be isolated in the free state on account of the readiness with which condensation takes place with formation of cyclic compounds (Wohl and Schafer, Brr., 1905, 38, 4157). It was found, however, that the corresponding acetal (y-aminobutyrylacetal) could be employed in place of the aldehyde, and that by heating with zinc chloride and phenyl- hvdrazine, condensation was effected, alcohol and ammonia being eliminated, and a good yield of the desired base thus obtained. The reaction must be represented thus: /\ NH-NHj NH The picrate of the base was found to be identical in all respects.