Abstract: In order to obtain more effective glycyrrhetinic derivatives, 3-amino acid derivatives were synthesized from glycyrrhetinic acid via deoxidation of the 11-carbonyl group, ethyl esterification of the 30-carboxylic group and esterification of 3-hydroxyl group using Fmoc-protected amino acids, which include methionine, threonine, valine and phenylalanine, by dicyclohexylcarbodiimide(DCC)/dimethylaminopyridine(DMAP) coupling method in tetrahydrofuran. The final products were obtained by removing Fmoc using V(CH2Cl2)∶V((C2H5)2NH)=1∶1 solvent mixture with 80%~87% yields and characterized by 1H NMR and MS. Preliminary pharmacological research showed that compounds 5a~5d could protect the growth of E col., Bacillus Subtilis and Yeast against high level of N,N-dimethylformamide.

Key words: Glycyrrhetinic, Fmoc protected amino acids, deoxidation, esterrification, deprotect