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 ε-caprolactone (ε-CL) by the multifunctional initiator EGP was carried out at 70 °C in bulk. Products of variable oligo(ε-CL) chain length (Mn = 450, 2200) were formed by variation of the ε-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 (Mn = 7200). Structural analysis by 1H, 13C, and COSY (13C-13C) NMR experiments showed that the reaction was highly regiospecific; i.e., the oligo(ε-CL)/oligo(TMC) chains formed were attached by an ester/carbonate link exclusively to the primary hydroxyl moiety of EGP.