Solid-phase synthesis of Phakellistatin 13 based on photolabile protecting strategy

Objective Preparation of the Phakellistatin 13 by using of solid-phase peptide synthesis method and photolabile protecting group. Methods By using of the DHP resin as the solid-phase supporter,a threonine derivative which was protected by the self-prepared photolabile protecting group was anchored to. The linear peptide was assembled via standard procedure with the threonine as the starting amino acid. After that,the photolabile protecting group was removed by UV irradiation,and the cyclization was completed while the peptide was still attached on the beads. The free cyclic peptide was then cut off by acid. Results The photolabile 2-(2-nitrophenyl)-propanol(Npp-OH) was synthesized in one step from o-nitroethylbenzene. With the Npp group,the carboxyl group of threonine was blocked and Phakellistatin 13 was synthesized. The Phakellistatin 13 was identified by high resolution mass spectrometry,indicated that the strategy is quite available,which offer an efficient method for cyclic peptide synthesis. Conclusion The Npp group had the advantages of easy prepared,high yields for protection and deprotection,be stable to the acidic and alkaline conditions,therefore it is an excellent third division protecting group. With this group,the cyclic peptide can be synthesized efficiently.