Macrocycles. 13. Stannylenated Glucose Glycosides as Cyclic Initiators of ε-Caprolactone and the Synthesis of Biodegradable Networks

The tetraacetates of α- and β-methylglycosides of d -glucose were reacted with dibutyltin dimethoxide in hot toluene with elimination of methyl acetate. The stannylenated glucose derivatives having a five- and six-membered tin-containing ring were isolated in a crystalline form. The soluble α-glycoside was used as cyclic initiator for the polymerization of ε-caprolactone at 80 °C. It was found by 1 H NMR spectroscopy that the insertion of the lactone exclusively occurs into the six-membered ring at the Sn−O bond of C-6. At prolonged reaction times the stannylenated glucose began to degrade at 80 °C. However, at short reaction times ( t ≤ 2 h) the molecular weight of the macrocyclic polylactone could be controlled by the monomer/initiator ratio (M/I). When sebacoyl chloride was added at the end of the polymerization, all four Sn−O bonds of the active chain end reacted, and swellable, biodegradable networks were obtained. The volume expansion upon swelling depended on the M/I ratio of the ring-opening polymerization and on the solvent.