METHOD OF PREPARING CARBOXY-PROTECTED GLYCOPEPTIDES OF GLYCYRRHIZIC ACID Russian patent published in 1996 - IPC

FIELD: organic chemistry. SUBSTANCE: product: carboxy-protected glycopeptides which were prepared from glycyrrhizic acid without preliminary protection of hydroxyl-groups in carbohydrate moiety of molecule. Glycyrrhizic acid is treated with N-hydroxybenzotriazole and N, N′-dicyclohexylcarbodiimide at 0-5 C in the medium of tetrahydrofuran or dioxane for 1 hr, at the room temperature for 6-7 hr and activated tris-hydroxybenzotriazole ester of glycyrrhizic acid is obtained. The latter ester is reacted in solution with amino-component - L-amino acid esters (methyl, benzyl, p-nitrobenzyl or tert. -butyl) as their hydrochlorides, tosylates or benzosulfates in the presence of tertiary base (N-methylmorphine, triethylamine, tributylamine) at 0-5 C followed by mixture keeping at the room temperature for 24 hr. The yield of the end compounds is 82-94%. Synthesized compounds were used in medicine. EFFECT: improved method of synthesis.