Studies on Amino Acids and Peptides, 13 Improved Synthesis of 5-Thioxo-L-proline and of SomeN-Acyl andS-Alkyl Derivatives as Building Blocks in Peptide Synthesis

✍ Scribed by Larsen, Claus ;Kragh, Henrik ;Rasmussen, Preben B. ;Andersen, Torben P. ;Senning, Alexander

• Publisher: John Wiley and Sons
• Year: 1989
• Tongue: English
• Weight: 514 KB
• Volume: 1989
• Category: Article
• ISSN: 0947-3440
• DOI: 10.1002/jlac.198919890231

✦ Synopsis

L-Proline, S-alkyl-5-thioxo-, N-acyl-5-thioxoj Peptide building blocks ,/ 5-Thioxo-~-proline graphic purifications with different eluents were necessary to obtain a pure product. Compound 2 is synthesized by thionation of the lactam function with 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide (Lawesson's reagent, 3). When the reaction is carried out in 1,2-dimethoxyethane (DME) at room temperature, nucleophilic attack on 3 does not occur, and protection of the carboxy group of 1 is therefore not necessary. After introduction of a washing procedure a pure sample of 2 was obtained either by recrystallization or by simple column chromatography. This workup procedure is not restricted to small amounts of material, but can be scaled up as required. Several recrystallizations may, however, be needed.