Ornithine Sorensen

By a very similar series of reactions Sorensen has also synthesised ornithine he first introduces the phthalimide group into the sodium... 

Alanine, aspartic acid, glutamic acid, tyrosine, leucine, phenylalanine and also a-amino-n-caproic acid and a-aminobutyric acid have in this way been separated by Fischer into their optically active isomers. To these must be added ornithine which was synthesised by Sorensen in 1903, and separated into d- and 1-ornithine in 1905. 

L-Arginine (precipitated as silver salt, lat. argentum) from seedlings of Lupinus by E. Schulze and E. Steiger. Recognized as a protein component 1895 by S.G. Hedin. Structure E. Schulze and E. Winterstein, 1897. Synthesis S.P.L. Sorensen, via L-ornithine, 1910. 

Scheme 12.35. An early synthesis of ornithine (after Sorensen, S. P. L. Chem. Ber.y 1910,43, 643) making use of phthalimide. Ornithine was prepared on the way to arginine (Arg, R) as shown in Scheme 12.36.

Synthesis. Schulse and Winterstein (706, 708) prepared 1 g. of arginine nitrate by allowing a solution of cyanamide and ornithine to evaporate over sulfuric acid for three weeks while Sorensen et al. (747, 750) synthesized arginine nitrate by the reaction of cyanamide and a-benzoylamino-S-amino-n-valeric acid. Ornithine is readily synthesized from cyclopentanone by the methods described by Fox et al. (328) and Albertson and Archer (47) and ornithuric acid ( , -dibenzoylamino-n-valeric acid) is easily prepared by the benzoylation of ornithine. The other steps in the described syntheses of arginine are less satisfactory since they involve either tiie selective reaction of cyanamide with the 8-amino group of ornithine or the selective hydrolysis of the 8-benzoyl group of ornithuric acid. 

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