The tautomerism of glyoxalines and the constitution of pilocarpine / by Frank Lee Pyman.

  • Pyman, Frank Lee.
Date:
[between 1910 and 1919?]
Catalogue details

Licence: In copyright

Credit: The tautomerism of glyoxalines and the constitution of pilocarpine / by Frank Lee Pyman. Source: Wellcome Collection.

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    ! CXCV.—The Tautomerism of Glyoxalines and the Constitution of Pilocarpine, By Frank Lee Pyman. Since the suggestion of Pinner and Schwarz {Ber.y 1902, 35, 2441), followed by the experimental proof adduced by Jowett (Trans., 1903, 83, 438), that the glyoxaline radicle is contained in the alkaloid pilocarpine, and later the discovery by Pauly {Zeitsch. 'physiol. Gliem., 1904, 42, 508) of this radicle in histidine, synthetic experiments with glyoxalines have attracted the attention of a number of chemists. Quite recently an added stimulus has been given to the work through the discovery by Barger and Dale (Proc., 1910, 26, 128) that j8-iminazolylethylamine, a compound which was recently synthesised by Windaus and Vogt (Ber., 1907, 40, 3691), is one of the active principles of ergot. Some years ago Dr. Jowett (Jowett and Potter, Trans., 1903, 83, 464; Jowett, Trans., 1905, 87, 405), with a view to syntheses in this field, commenced a series of investigations, which will be referred to in detail later, and more recently, being unable to resume the work personally, requested the present author to continue it. The most important result of the present investigation is the proof that glyoxalines, containing a free imino-hydrogen atom, are tautomeric, a fact which previous research on the subject had already made probable. Thus, Janecka {Ber., 1899, 32, 1098) pre¬ pared, by the oxidation of the mercaptan formed by the action of potassium thiocyanate on a-aminodiethyl ketone (I), the same methylethylglyoxaline (II or III) which Gabriel and Posner (Ber., 1894, 27, 1037) had previously obtained in a similar manner from a-aminopropyl methyl ketone (IV) : CHMe-NHg COEt (h) CMe*NH CEt—N (II.) >CH, or CMe—N. COMe CEt-NH-^ CHEi-KHg '(HI.) (IV.) This method of synthesis does not enable any conclusion to be drawn as to which of the two isomerides, 5-methyl-4-ethylglyoxaline (II) and 4-methyl-5-ethylglyoxaline (III), is to be expected in each case, but it was inferred that a different one of the two would be expected in the two cases; the fact that the same methylethyl¬ glyoxaline was actually obtained in each case consequently showed either that this compound is tautomeric, or that one of the two forms (II) and (III) is the more stable. Janecke thought the former