Abstracts Chemistry

The synthesis and cyclization of 2,4-diaminobutyric acid

by Chun-wing Li

The objectives of this study were to isolate 2, 4-diaminobutyric acid and to attempt cyclizing the acid and its disulfonamide derivative. The original synthetic method by Adamson was followed but a modified isolation procedure for the acid was employed. Following the synthesis, the acidic solution was passed through Dowex-3 ion-exchange column twice to remove sulphuric acid and any unreacted glutamic acid completely. The eluate was then concentrated to obtain the 2, 4-diaminobutyric acid or excess hydrochloric acid was added to ensure obtaining the dihydrochloride salt. Excess acid, which was used for the isolation however, left an unknown residue in the alcohol, possibly as the ethyl ester of the dihydrochloride. The 2, 4-diaminobutyric acid was characterized by preparation of the dipicrate. Cyclization of the free acid was attempted with thionyl chloride and phosphorus oxychloride respectively. However, the resulting dark and sticky resin did not give any cyclization product. Nevertheless, when acetic anhydride was employed, I-acetyl-3-acetamido-2-pyrrolidone was obtained in very low yield. The disulfonamide derivative was synthesized. Treating this compound with either thionyl chloride or phosphorus pentachloride gave the lactam, 1-p-toluene sulfonyl-3-(p-toluenesulfonamido)-2- pyrrolidone.