282529-05-9Relevant articles and documents
Application of nim-2,6-dimethoxybenzoyl histidine in solid-phase peptide synthesis
Zaramella, Simone,Stroemberg, Roger,Yeheskiely, Esther
, p. 2454 - 2461 (2003)
Fmoc-histidine derivatives protected with 2,6-dimethoxybenzoyl (2,6-Dmbz) units, either on the τ- (1) or on the π-position (2) of the imidazole residue, have been prepared and applied to the synthesis of the dipeptide Fmoc-His(2,6-Dmbz)-Val-OMe, with high coupling efficiencies (99 and 95%, respectively) and low racemization (0.3 and 0.1%, respectively), as ascertained by HPLC analysis on the fully protected dipeptides. In addition, the hexapeptide H-Ala-Ser-Val-His-Val-Phe-OH (I) has been synthesized on a solid support employing the novel building blocks 1 and 2 as well as commercially available Fmoc-His(t-Trt)-OH (3). The crude deprotected products were analyzed by reverse-phase HPLC and mass spectrometry, which indicated that when the τ-protected derivatives 1 and 3 were employed the products were of comparable quality (93-94% major peak). The hexapeptide synthesized with the π-protected histidine 2 was contaminated with a product corresponding to 2,6-Dmbz-His-Val-Phe-OH (12), which was probably formed through the intramolecular acyl transfer of a 2,6-Dmbz unit from the π-nitrogen atom to the α-amino group of the N-terminal histidine unit upon removal of the Fmoc group. This side reaction was insignificant (less than 0.5%) when using the τ-protected derivative 1. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).
