Synthesis and organocatalytic ring-opening polymerization of cyclic esters derived from l-malic acid.
The synthesis of 3-(S)-[(benzyloxycarbonyl)methyl]-1,4-dioxane-2,5-dione (BMD) and 3,6-(S)-[di(benzyloxycarbonyl)methyl]-1,4-dioxane-2,5-dione (malide) from commercially available l-malic acid is reported. Ring-opening polymerization (ROP) studies of BMD are reported showing that the controlled ROP of this monomer is possible in the absence of transesterification side reactions, despite the presence of side-chain esters, using 1-(3,5-bis(trifluoromethyl)phenyl)-3-cyclohexylthiourea and (-)-sparteine to catalyze the polymerization. The ROP of malide with this system was ineffective. Investigation of the effect of initiating species revealed that the electronic nature of the alcohol had a greater effect on the ultimate molecular weight and hence initiator efficiency than steric considerations. Deprotection of the resultant poly(BMD) using H(2) and Pd/C resulted in hydrophilic poly(glycolic-co-malic acid)s (PGMAs) that were able to undergo autocatalytic degradation in dilute H(2)O solution such that complete degradation was observed within 6 days.
Pounder
Ryan J
RJ
Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
Dove
Andrew P
AP
D002384:Catalysis; D004951:Esterification; D004952:Esters / Q000138:chemical synthesis* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008293:Malates / Q000737:chemistry*; D008970:Molecular Weight; D011108:Polymers / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization
D004952:Esters; D008293:Malates; D011108:Polymers; C030298:malic acid