The Synthesis of Tryptophan Peptides

Abstract

overnight at 100°under oil pump vacuum it lost 0.97% water and melted at 240-241°with a sinter at 201°.

Carbon‐14 labeling of K777•HCl, a therapeutic agent for Chagas disease

“…K777 can be disconnected retrosynthetically (Scheme ) into N ‐methylpiperazine, phosgene (or a synthetic equivalent), ( l )‐phenylalanine, and chiral amine 1 , as was described previously by Somoza . The choice of site for radiolabeling was twofold: (1) the phenylalanine unit is metabolically stable; and (2) phenylalanine uniformly labeled with carbon‐14 is commercially available.…”

Structural Biochemistry XIII: Synthesis of Luteinizing Hormone - Releasing Hormone Modification [ Trp8]- LH - RH

“…solution prepared from NimHzl-Roc-His (5.10 g, 14.8 mmoles) (26), Trp-ORzl hydrochloride (4.87 g, 14.8 mmoles) (27), 1 -hydroxyhenzotriazole (3.95 g, 29.6 mmoles), Nmethylmorpholine (1.66 ml, 14.8 mnioles), and dimethylformamide (100 ml) was cooled to O", and dicyclohexylcarl)odiimide (3.34 g. 16.3 mmoles) was added. The mixture was stirred a t 0" for 1 hr and a t 23" for 16 hr.…”

Configuration of echinulin. II. Optical rotatory dispersion of echinulin, hydroechinulin, and the stereoisomeric 3-methyl-6(indolyl-3-methyl)-piperazine-2,5-diones

“…If free peptide precipitated during hydrogenolysis it was dissolved by addition of water. The reaction mixture was filtered and the filtrate evaporated to dryness under reduced pressure at 50" to give tryptophylalanine as a white solid (90-95 %) which was chromatographically pure (23). The tryptophylalanine tended to decompose (judged by the development of a yellow-brown color) when subjected to recrystallization procedures and the product obtained from hydrogenolysis was used directly in the following step.…”