Modified Poly(ε-caprolactone)s: An Efficient and Renewable Access via Thia-Michael Addition and Baeyer–Villiger Oxidation

The preparation of a novel class of ε-caprolactone (CL) monomers, modified at the β-position of the ester function, is described. The efficient thia-Michael addition to cyclohex-2-en-1-one and subsequent Baeyer–Villiger oxidation provided the regioselectively modified CL monomers. To enable a sustainable Baeyer–Villiger oxidation, several reaction procedures were investigated. In order to test a controlled ring-opening polymerization of the prepared monomers, the kinetics were studied and the monomer to initiator ratios were varied in order to prepare poly­(ε-caprolactone)­s with different molecular weights and different side groups.