Chemical synthesis of poly-gamma-glutamic acid by polycondensation of gamma-glutamic acid dimer: Synthesis and reaction of poly-gamma-glutamic acid methyl ester

摘要

alpha -Methyl glutamic acid (L-D)-, (L-D)-, (D-L)-, and (D-D)-gamma -dimers were synthesized from L- and D-glutamic acids, and the obtained dimers were subjected to polycondensation with 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 1-hydroxybenzotriazole hydrate as condensation reagents. Poly-gamma -glutamic acid (gamma -PGA) methyl ester with the number-average molecular weights of 5000 similar to 20,000 were obtained by polycondensation in N,N-dimethylformamide in 44 similar to 91% yields. The polycondensation of (L-L)- and (D-D)-dimers afforded the polymers with much larger /[alpha](D)(30)/ compared with the corresponding dimers. The polymer could be transformed into gamma -PGA by alkaline hydrolysis or transesterification into alpha -benzyl ester followed by hydrogenation. (C) 2001 John Wiley & Sons, Inc. [References: 12]