Ethyl glucoside as a multifunctional initiator for enzyme-catalyzed regioselective lactone ring-opening polymerization

The one-pot biocatalytic synthesis of novel amphiphilic products consisting of an ethyl glucopyranoside (EGP) headgroup and a hydrophobic chain is described. The porcine pancreatic Lipase (PPL) catalyzed ring-opening polymerization of epsilon-caprolactone (epsilon-CL) by the multifunctional initiator EGP was carried out at 70 degrees C in bulk. Products of variable oligo(epsilon-CL) chain length (M-n = 450, 2200) were formed by variation of the epsilon-CL/EGP ratio. Extension of this approach using Candida antarctica lipase (Novozym-435) and EGP as the initiator for trimethylene carbonate (TMC) ring-opening polymerization also resulted in the formation of an EGP-oligo(TMC) conjugate (M-n = 7200). Structural analysis by H-1, C-13, and COSY (C-13-C-13) NMR experiments showed that the reaction was highly regiospecific; i.e., the oligo(epsilon-CL)/oligo(TMC) chains formed were attached by an ester/carbonate link exclusively to the primary hydroxyl moiety of EGP.