Über Peptidsynthesen, II. Herstellung und Verwendung der Dicyclohexylammoniumsalze von Acylaminosäuren und Acylpeptiden

Abstract

16, 223 (1947), mit ihren ersten drei Buchstaben benannt. I ) F. WEYGAND und M. REIHER, Chem. Ber. 88, 26 (1955).

Recognition of quaternary ammonium salts with tetrapeptides containing α-aminoisobutyric acid as a conformational constraint

“…Guests studied included phenyltrimethylammonium chloride (3), benzyltrimethylammonium chloride (4), dodecyltrimethylammonium chloride (5), acetylcholine chloride (6), N-butylpyridinium chloride (7) and N-methylisoquinolinium iodide (8) as quaternary ammonium salts, and tert-butylbenzene (9) and N,N-dimethylaniline (10) as structurally similar but non-ionic guests. The complexation of the peptide host and ammonium guest in CDCl 3 was clarified by monitoring the host-induced upfield shifts of the guest 1 H signals in response to the ring current effect of the benzene and indole rings of the host.…”

N-Methylamino Acids in Peptide Synthesis. III. Racemization during Deprotection by Saponification and Acidolysis

“…T h e resulting oil was extracted into ethyl acetate (2 x 30 ml), the extract was dried and evaporated to an oil. The oily 2-Ala-Leu was converted to the dicyclohexylarnmoniuni salt as described (24), recrystallized, m.p. 162-163", lit.…”

Immunochemical Studies on the Poly-γ-D-glutamyl Capsule of Bacillus anthracis. II. The Synthesis of Eight Dipeptides and Four Tripeptides of Glutamic Acid*

“…iV-Carbobenzoxy-T-benzyl-D-glutamic acid dicyclohexylamine salt (Hanby et al, 1950;Klieger et al, 1961) was transformed to the free acid by adding 32 g (57 mmoles) of the salt to a separatory funnel containing 750 ml of 1 n hydrochloric acid and 2 1. of ethyl acetate and shaking vigorously. An emulsion containing some solid was formed between the two layers.…”

“…All these blocking groups were removed in a single step by catalytic hydrogenolysis. For the synthesis of a-dipeptides, the appropriate carbobenzoxyglutamic acid -benzyl ester (Hanby et al, 1950), freed from its dicyclohexylamine salt (Klieger et al, 1961), and dibenzyl glutamate, liberated from its p-toluenesulfonic acid salt (Bose and Strube, 1963), were employed. The protected a-dipeptides were found to be gelatinous solids and could not be purified effectively by crystallization; they were subjected to purification by countercurrent distribution.…”