Patent ID: 8329853
Filing Date: 2012-12-11
Classification: C07K,C08G

Abstract:
1. A process for the preparation of poly-α-glutamic acid of formula (I) wherein the symbol * indicates a chiral center and n is between 60 and 310, so that the poly-α-glutamic acid has a molecular weight ranging from 8,000 to 40,000 Da said process comprising the steps of: a) polymerization of a tertiary γ-ester of α-glutamic acid N-carboxy anhydride of formula (II) wherein the symbol * is as defined above and R is selected from t-butyl, 1,1-dimethylpropyl and 1,1-dimethylbutyl in water or in an organic solvent selected from: tetrahydrofuran, 1,4-dioxane, dimethylformamide, 1,4-dioxane/DMF and 1,4-dioxane/tetrahydrofuran mixture with an initiator selected from potassium tert-butoxide, sodium methoxide, diisopropylethylamine, 1,8-diazabicyclo[5,4,0]undec-7-ene, dimethylaminopyridine and L-glutamic acid-γ-tert-butylester, to give a compound of formula (III) wherein * and R are as defined above and R′ is hydrogen when the initiator is selected from diisopropylethylamine, 1,8-diazabicyclo[5,4,0]undec-7-ene, 4-dimethylaminopyridine, glutamic acid dimethyl ester and glutamic acid-γ-tert-butyl ester or R′ is a t-butyl or methyl group when the initiator is potassium tert-butoxide and sodium methoxide respectively; and followed by b) acid hydrolysis of the γ- and α-ester groups to give a compound of formula (I).