Direct Organocatalytic Chemoselective Synthesis of a Dendrimer-like Star Polyester

We have developed a direct organocatalytic synthesis of a dendrimer-like star polyester. The synthesis was based on lactic acid-catalyzed bulk ring-opening polymerization (ROP) of ε-caprolactone (ε-CL) with the hexahydroxy-functional dendrimer 2,2-bis(hydroxymethyl)propanoic acid as the initiator. The polymerization was highly chemoselective, and the catalyst was readily recovered by precipitation of the polyester products. The reaction was performed without solvent and without the need of an inert atmosphere. In addition, the ROPs are operationally simple, inexpensive, and environmentally benign. Organic acid catalysis provides a new entry for the synthesis of valuable dendritic materials as well as polyesters for biomedical applications.