Synthesis of a thiol‐terminated poly(L‐glutamic acid) by polymerization of N‐carboxyanhydrides on solid supports

Abstract

AbstractA novel method of synthesizing a thiol‐terminated poly(L‐glutamic acid)IUPAC name: α‐hydro‐ω‐(2‐mercaptoethyl)amino‐poly{sodium imino‐[1‐(2‐carboxylatoethyl)‐2‐oxo]ethylene}. (PLGA) is reported. Synthesis of this compound is accomplished with the aid of a solid phase support. The procedure consists of first preparing aminoethyl disulfide‐functionalized silica, glass or polystyrene solid supports. The support thus prepared is then reacted with ester‐protected γ‐benzyl‐L‐glutamate or γ‐piperonyl‐L‐glutamate N‐carboxyanhydride (NCA) to obtain the conjugated poly(γ‐ester‐L‐glutamate)‐support. Then the protected ester group is acidolyzed by adding hydrobromic acid or trifluoroacetic acid (TFA). Finally, the disulfide bond of the resulting acid is cloven by reacting it with mercaptoethanol thus producing the desired end product, the thiol‐terminated poly(L‐glutamic acid) (yield 64%).