Aluminum complexes based on pyridine substituted alcohols: synthesis, structure, and catalytic application in ROP†
Abstract
A series of substituted pyridine dialcohols (2,6-bis(hydroxyalkyl)pyridines), 1–4, was used for the synthesis of various types of aluminum complexes. Aluminum methyl derivatives, 2–4a, were obtained by the reaction of AlMe3 with the corresponding ligand or transmetallation reactions of germylenes. Aluminum chloride complexes, 3–4b, were obtained by substitution of the Me group under the action of chlorinating agents. Methoxy-, 2–4c, or benzyloxy-, 2d, aluminum complexes were synthesized in transalkoxylation reaction of Me2Al(OX) (X = Me, Bn) by the corresponding ligand. All complexes obtained were thoroughly investigated by multinuclear NMR and X-ray analysis. It has been established that the structure of the ligand (number of carbon atoms) determines the nature of the complexes formed. Compounds were used as initiators of ring-opening polymerization of L-lactide and ε-caprolactone and showed moderate activity with controlled or immortal character.