Síntesis de Aminoácidos Marcados. I. Síntesis de DL-Valina-1-C14 y DL-Leucima-1-C14

Abstract

The preparation of DL-Valine-1-C14 and DL-Leucine-1-C14 is described. The starting materials are isobutjdbromide and isoamylbromide respectively, and the synthesis goes through the carbonation of the corresponding Grignard conipound with C14 02, bromination of the carboxylic acid obtained and ainmonolysis of the a-bromoacid. Desalting is aocomplished by means of an ion exohange resin (Dowex 50) and th e final purification, by recrystanization from an ethanol-water niisxture. The isotopic purity of the products obtained is established by paper ehromatography and autoradiography. In the case of the purification of vahn e-l-C14 it is necessary to make use of cellulose column chrom atography in order to get rid of an active impurity whieh behaves hke an active a-aininoacid. It is quite cerlain th a t the active impurity takes its origin in the bromination stage of the synthesis.