The synthesis of glyoxaline derivaties allied to pilocarpine / by Frank Lee Pyman.

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

Licence: In copyright

Credit: The synthesis of glyoxaline derivaties allied to pilocarpine / by Frank Lee Pyman. Source: Wellcome Collection.

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    *~7 LXI. The Synthesis of Glyoxaline Derivatives Allied to Pilocarpine. By Fkank Lee Pyman. The idea of preparing glyoxalines containing acidic groups anaio- gous to the homopilopic complex in pilocarpine by condensing a suitable bromoglyoxaline with substances such as ethyl sodio- malonate was put forward by Jowett in 1905 (Trans,, 87, 405). Owing, however, to the difficulty of obtaining at the time suitable bromoglyoxalines in good yield, no condensation experiments were actually carried out. Since then the present author—continuing this line of work at Dr. Jowett’s request—has prepared and charac¬ terised the bromo- and dibromo-derivativea of 4(or 5)-methylglyoxa- line, 1:4-dimethylglyoxaiine, and 1:5-dimethylglyoxaline (Trans., 1910, 97, 1814). A number of bromoglyoxalines being thus avail¬ able, attempts were made to bring them into reaction in various ways, but in every case unsuccessfully. In the first place, it v as found that these compounds were quite unaffected when heated with ethyl sodiomalonate or ethyl sodio- acetoacetate under various conditions, for in each case the bromo¬ glyoxaline was recovered unchanged, and no bromide could be detected in the reaction mixture by means of silver nitrate. The stability of the bromoglyoxalines indicated by these results is comparable with that of bromobenzene. This compound may be readily brought into reaction by Grignard’s method, and attempts were theiefoie made to convert bromoglyoxalines into magnesium glyoxalyl bromides, which might then be used for the preparation of derivatives in the usual manner. All attempts, however, to effect the combination of bromoglyoxa¬ lines with magnesium, whether by adding traces of iodine or methyl iodide or by using “ active ” magnesium (Baeyer, Ber., 1905, 38, 2759), were unsuccessful. Finally, it was thought that bromoglyoxalines might possibly be brought into reaction by heating them with magnesium alkyl halides at high temperatures, a method employed by Grignard (Conipt. rend., 1904, 138, 1048), and subsequently by Wohl and Berth old {Ber., 1910, 43, 2177), for the preparation of derivatives of co-bromo- phenetole. This method was also unsuccessful, for on heating 2 :4-dibromo-l: 5-dimethylglyoxaline with magnesium methyl iodide or magnesium phenyl bromide for several hours in boiling xylene, the bromine atoms were to some extent replaced, not by alkyl groups, but by hydrogen, 2(or 4)-bromo4 :5-dimethylglyoxaline and