Hermann Leuchs

In 1906 Leuchs observed, first on glycine, that iV-carboethoxyamino acid chlorides at temperatures as low as 70 °C are transformed, with the loss of alkyl chloride, to the so called Leuchs schen Korper (Leuchs substances), N carbamoic acid amino acid inner anhydrides. As he noted in the case of the glycine derivative these AT-carboxyanhydrides (NCA-s) readily polymerize. For instance in the presence of a small amount of water they form poly-a-amino acids consisting, as shown by later studies, of several hundred residues. 

Leuchs initial elan, fed by intelligence and power of imagination, which after successful (albeit by Emil Fischer inspired) peptide studies launched him into the difficult chemistry of strychnine alkaloids and also into problems of stereochemistry, diminished later, probably under the influence of some decisive inner experience unknown to us. After a while his life was consumed by work in the laboratory he remained unimpressed by the rich cultural and scientific distractions offered by Berlin, that time in its heydays. After 1908 his principal field became strychnine chemistry and related alkaloids 125 of his 178 publications deal with this topic. 

He led a simple life, more and more isolated in the apartment which he had already occupied as a student and kept for many years. He looked upon the Hitler-movement first with suspicion and later with outright hatred. During the Nazi-era Leuchs witnessed the destruction of Nuremberg, the city where he was born, and of Berlin, where he lived. He sank into deep melancholy and in 1945, in the last days of the war he himself put an end to years of hopeless suffering. 

The Leuchs substances, NCA-s, oxazolidine-2,4-diones, can also be synthesized by the method of Fuchs (1910) from amino acids and phosgene, a method further developed by Farthing (1950). According to Curtius, NCA s can be generated from malonic acid half azides as well, through a-isocyanatocarbonic acids (Curtius degradation. Fig. 4). 

The NCA-s are extremely reactive compounds (see Fig. 5). The inner anhydride grouping is cleaved by nucleophiles the attack preferentially occurs at the CO group of the amino acid. With water an AT-carboxy-amino acid is formed which spontaneously loses CO2. The thus liberated amino group can then attack a second NCA molecule. The NCA-s react with HCI, for instance according to M. 

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In 1906, Hermann Leuchs, one of Emil Fischer s most distinguished associates, made an ingenious step in the direction of... 

Leuchs described the synthesis of several representative anhydrides of type 1 having different substituents. Although the discovery of Hermann Leuchs did not attract much attention at first, it has been expanded into one of the most important synthetic tools in protein research. Emil Fischer, whose institute in Berlin occupied a leading role in the research on sugars and proteins for 30 years, expressed at several occasions the opinion that his own synthetic polypeptides, and by extrapolation natural proteins, would be represented by long chains with the -CO-NH- unit as a recurring bond. 

N-Carboxy anhydrides (NCA), Leuchs s anhydrides, l,3-oxazolidine-2,5-diones, cyclic compounds containing an activated carboxy group and an acyl-protected amino function, first discovered by Hermann Leuchs in 1906. Under carefully controlled conditions, NCAs can be mono-coupled to the nitrogen of an unprotected amino... 

Leuchs, Hermann (1879-1945), German chemist and discoverer of the N-carboxy anhydrides of amino acids. He carried out the work for his doctoral thesis under the direction of Emd Fischer on the synthesis of serine and glucosamine. In 1902, he received his D. Phd. degree and achieved independent status from 1904 onwards, Privatdozent (1910) and associate professor (1914). He turned down offers of frill professorships at the Universities of Graz and Braunschweig, which would have improved his position, in favor of a personal frill professorship at the Berlin Institute. He ended his life in the final days of World War II [F. Krohnke, Hermann Leuchs , Chem. Ber. 1952, 85, LV]. 

Leuchs, Hermann (1879-1945, p. 35, Plate 29) born in 1879 in Nuremberg, studied chemistry in Munich and graduated in 1902, Ph.D. with a thesis guided by E. Fischer in Berlin. He then became associate professor there and, in 1926 Associate Director of the Institute of Chemistry of the University. After his discovery of the Leuchs substances (p. 35) in 1906 and some of their reactions he turned to strychnine chemistry on which he worked until his death in the destroyed Berlin in 1945. 

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