| 摘要 |
1,221,238. o-Ethyl threonine and derivatives thereof; organomercury compounds. MERCK & CO. Inc. 16 Dec., 1968 [22 Dec., 1967], No. 59680/68. Headings C2C and C2J. Novel o-ethyl threonine derivatives of the Formula I: in which R 2 is H or a substituent cleavable by body processes and R 3 is OH or an unsubstituted or inertly substituted C 1-10 alkoxy, cycloalkoxy, monocyclic aryloxy, amino, hydroxylamino or hydrazino and non-toxic pharmaceutically acceptable salts thereof are prepared by ethoxylating the olefinic double bond of (a) crotonic acid, (b) an ester of 2-nitrocrotonic acid or (c) a readily cleavable N-substituted ester of 2- aminocrotonic acid and treating the intermediates thereby obtained, respectively by (a) halogenation followed by ammonolysis, (b) controlled reduction of the nitro group or (c) hydrolysis, thereby forming o-ethyl threonine which is converted, if desired, into compounds of the above general formula by standard methods. Alternatively o-ethyl threonine is made by reacting 2-ethoxy-propionaldehyde with (a) ammonia and hydrogen cyanide, (b) ammonium chloride and an alkali metal cyanide, (c) ammonium carbonate and hydrogen cyanide, or (d) ammonium carbonate and an alkali metal cyanide, and hydrolysing the intermediate thereby obtained. 2-Bromo-3-ethoxybutyric acid is obtained by brominating 2-acetoxy-mercuric-3-ethoxybutyric acid, resulting from the addition of crotonic acid to a mixture of mercuric acetate and anhydrous ethanol. DL - N - Formyl - O - ethyl threonine is prepared by reacting DL-threo and erythro-2-amino- 3-ethoxybutyric acid with formic acid and acetic anhydride. Veterinary compositions, having activity against pleuropneumonia-like organisms, contain the above compounds of Formula I and suitable diluents or carriers. The compounds may be incorporated into animal feedstuffs, drinking water, boluses, or drenches. The compositions may also be administered by subcutaneous injection. |
