Cryochemistry: freezing effect on peptide coupling in different organic solutions

✍ Scribed by Tamás Vajda; Gyula Szókán; Miklós Hollósi

• Book ID: 101283280
• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 75 KB
• Volume: 4
• Category: Article
• ISSN: 1075-2617
• DOI: 10.1002/(sici)1099-1387(199806)4:4<300::aid-psc148>3.0.co;2-i

✦ Synopsis

The freezing effect on peptide coupling in organic solutions of different polarity has been investigated and compared with the results obtained in liquid phase. The model reaction of DCC-activated coupling of Boc-Ala-Phe-OH with H-Ala-OBu t has been carried out in dioxane, dimethylsulfoxide and formamide, as well as in mixtures (90%/10%, v/v) of dioxane with acetonitrile, dimethylformamide, dimethylsulfoxide and formamide.

The reactions have been traced and evaluated by RP-HPLC analysis. Freezing the reaction mixture resulted in all cases in a significant suppression of the N-dipeptidylurea side-product formation together with a slight decrease of tripeptide epimerization. The coupling yields and the side effects depended on the solvent, with the dioxane and dioxane/acetonitrile mixture produced the best results. The role of freezing and solvent in the improved results is discussed.