Study On Synthesis Of Peptides RADA Using In Molecular Self-assembly

In this paper peptides RADA were synthesized which was the lest unit of (RADA)4, and can use in molecular self-assembly. This study provided material base for molecular self-assembly.This synthesis started with the protection of the amino acid, successfully protecting the amino, the carbonyl and the guanidine of argine , gaining these intermediates:BocArg(NO₂)OH,Z-Ala,BocAsp(OBzl)OH,AlaOBzl·TosOH. Products were confirmed by Infrared spectra, Melting point and TLC. When synthesis Z-Ala, the optimal operation variables were determined through orthogonal experiment: when 4.685g L-Ala, 4ml Z-Cl are introduced, reaction temperature is 25℃and reaction time is 2 hour, pH=9, the highest yield was obtained.Selected the reverse synthetical route beginning from the last amino acid. HOBt, DCC were used as the coupling agents, Et3N was used to regulate pH, THF were used as solvent, HCl/ethyl acetate and HBr/HOAc were used as deprotecting reagent. Benzyl groups were removed from the protected peptide by catalytic hydrogenolysis over palladium-carbon. The crudes were purified by silica gel chromatograph and the crude peptides were purified by recrystallization using EtOH and H2O. Products were confirmed by Infrared spectra, ¹HNMR, Melting point and TLC. The experiment data indicated that in the liquid-phrase synthesis using HOBt, DCC and Et3N as coupling agents and HCl/ethyl acetate for deprotection of Boc,HBr/HOAc for deprotection of Z might be a good way of combination for synthesis.