Synthesis of X(Y)-(EO)(n)-OCH₃ type heterobifunctional and X(Y)-(EO)(n)-Z type heterotrifunctional poly(ethylene glycol)s.

A synthetic route to prepare acetal-protected heterobifunctional poly(ethylene glycol), allyl(1-ethoxyethoxy)-PEG-OH (allyl(EE)-PEG-OH), was successfully established using a newly synthesized initiator, trimethylolpropane allyl (1-ethoxyethoxy) ether (TMPAEEE). Heterobifunctional allyl(OH)-mPEG and heterotrifunctional allyl(OH)-PEG-alkyne were obtained, respectively, after modification from this precursor polymer. The polymers were characterized by SEC, ¹H NMR, and MALDI-TOF mass spectroscopy. This approach is applicable for synthesizing a wide variety of X(Y)-(EO)(n)-OCH₃ type heterobifunctional and X(Y)-(EO)(n)-Z type heterotrifunctional PEGs.