Synthesis And Gelation Of L-phenylalanine Derivative

S- ibuprofen has good anti- inflammatory effect, but the half- life is short. L- phenylalanine is one of the essential amino acids to human. It has been widely used in medicine industry due to its good biocompatibility and biodegradability. It is possioble to solve the problem that the frequent administration of S-ibuprofen by grafting S- ibuprofen onto the amino acid to preparat gel.Target product E, N-(2-(4-isobutylphenyl)propanoyl)-L-phenylalanyl- L-phenylalanine, was synthesized from S-ibuprofen and L-phenylalanine by reactions:(1) esterification of Lphenylalanine to L- phenylalanine methyl ester hydrochloride;(2) acylation of the carboxyl group of S- ibuprofen to 2-(4-isobutylphenyl) propanoyl chloride(B);(3) amidation of L-phenylalanine to form N-(2-(4-isobutylphenyl)propanoyl)-L-phenylalanine(C);(4) anhydride amidation of(C) to form N-(2-(4-isobutylphenyl)propanoyl)- L-phenylalanyl-L-phenylalaninate methyl ester(D)and(5) hydrolysis of(D) to form(E). The synthesis conditio ns were explored and optimized. The structures of the produc ts were characterized by using IR, 1HNMR, 13 CNMR, ESI-MS and other methods.The gelation of the target product E was explored. Compound E formed gel in water solution(with the help of DMSO); the minimum gel concentration was 1%; Tgel increased from 35℃ to 50℃ when concentration from 1% increased to 4%. In toluene solution(with the aid of THF), compound E formed thermal reversible gel; the MGC was 6%; the morphology of the gel were characterized by SEM. SEM images showed that the natural drying gel had formed a lamellar structure, while the vacuum drying gel had formed a rod like structure. This paper provided some valuable data for the preparation of amino acid gels.