94 SCIENCE PROGRESS 
acid prepared by synthesis before Fischer commenced his re- 
searches was diaminopropionic acid, which was obtained by 
Klebs in 1894 by the action of ammonia on dibrompropionic acid. 
The similar reaction with a-6-dibromvalerianic acid did not lead 
to the synthesis of the expected diamino acid, but to the forma- 
tion of a-pyrrolidine carboxylic acid (Willstatter, 1900). 
By making use of Gabriel’s phthalimide method for synthesis 
with a slight modification Fischer prepared a-6-diaminovalerianic 
acid. The series of reactions occurring in the process are as 
follows: 
CH,<EQNK + Br. CH, CH. CH, Br + Na. CHE 9 9c 
COOC.H, 
= NaBr + KBr + Glico N.CH,. CH. CH. CH< C997? 
Bromination then gives 
ae COOC.H; 
CH.<é9>.N = CH,. CH,. CH. C <Br 
COOC,H; 
which, on hydrolysis and loss of carbon dioxide on heating, 
passes into phthalimidobromvalerianic acid: 
CGH,< CoN CH; CH, .Chae oe 
COOH 
This acid, on treatment with ammonia, whereby Br is exchanged 
for NH., and subsequent hydrolysis, yields a-é-diaminovalerianic 
acid : 
CoH, <COOH + H.N.CH,.CH;. CH, . CH(NH,). COOH 
The benzoyl derivative of this diamino acid only differed 
from Jaffe’'s ornithuric acid in optical activity; unfortunately, 
owing to lack of material, the separation of ornithine, as this 
diamino acid is called, into its stereoisomerides could not be 
carried out. Sorensen, however, some years later was able 
to accomplish this, and thus the synthesis of natural ornithine 
was completed. Ornithine is a product of the hydrolysis of 
arginine together with urea, and arginine was synthesised by 
Schulze and Winterstein in 1899 by the addition of cyanamide 
to ornithine. 
By the above series of reactions Fischer prepared a-y-di- 
aminobutyric acid, and the same reactions would lead to the 
synthesis of lysine, which Fischer and Weigert obtained by a 
simpler and better method, consisting of the following reactions: 
