The coupling reaction of carbon dioxide and terminal, internal, and highly substituted epoxides derived from renewable resources such as furfural, limonene, carvone, carvyl acetate, terpinen-4-ol, or ionone leads to the synthesis of new bioderived cyclic carbonates using an efficient aluminum catalyst under mild and solvent-free reaction conditions. Interestingly, the synthesis of highly substituted bioderived cyclic carbonates can occur with excellent diastereoselectivity, obtaining in some cases one diastereoisomer as the major product. The X-ray crystal structures of two enantiomerically pure carvonebased cyclic carbonates are reported.

The optimization of an organoaluminum catalytic system for the copolymerization of epoxides and anhydrides is presented. For this purpose, the influence of different variables in the process, such as catalysts, cocatalyst, solvent, or substrates, has been analyzed. Kinetic studies, a proposal for the catalytic mechanism, and full characterization of the copolymers obtained are also discussed. Finally, a new copolymer, poly(limonene succinate), obtained by the optimized catalytic system is reported.

A series of alkyl aluminium complexes based on heteroscorpionate ligands were designed as catalysts for the ring-opening polymerisation of cyclic esters and ring-opening copolymerisation of epoxides and anhydrides. Treatment of AlX3 (X = Me, Et) with ligands bpzbeH [bpzbe = 1,1-bis(3,5-dimethylpyrazol-1-yl)-3,3-dimethyl-2-butoxide], bpzteH [bpzte = 2,2-bis(3,5-dimethylpyrazol-1-yl)-1-para-tolylethoxide], and (R,R)-bpzmmH [(R,R)-bpzmm = (1R)-1-{(1R)-6,6-dimethyl-bicyclo[3.1.1]-2-hepten-2-yl}-2,2-bis(3,5-dimethylpyrazol-1-yl)ethoxide] for 2 hours at 0 °C afforded the mononuclear dialkyl aluminium complexes [AlMe2{κ2-bpzbe}] (1), [AlEt2{κ2-bpzbe}] (2), [AlMe2{κ2-(R,R)-bpzmm}] (3) and [AlEt2{κ2-(R,R)-bpzmm}] (4), and the dinuclear dialkyl complexes [AlMe2{κ2-bpzte}]2 (5) and [AlEt2{κ2-bpzte}]2 (6). The molecular structures of the new complexes were determined by spectroscopic methods and confirmed by X-ray crystallography. The alkyl-containing aluminium complexes can act as highly efficient single-component initiators for the ring-opening polymerisation of ε-caprolactone and l-lactide and for the ring-opening copolymerisation of cyclohexene oxide and phthalic anhydride to give a range of biodegradable polyesters.

Novel bimetallic zinc acetate complexes supported by heteroscorpionate ligands have been developed for the ringopening copolymerization of cyclohexene oxide and CO 2 and the terpolymerization of cyclohexene oxide, phthalic anhydride, and CO 2 . Heteroscorpionate ligands precursors L 1 −L 3 were reacted with two equivalents of zinc acetate to afford the dinuclear zinc complexes [{Zn(κ 3 -bpzappe)}(μ-O 2 CCH 3 ) 3 -{Zn(HO 2 CCH 3 )}] (1), [{Zn(κ 3 -bpzbdmape)}(μ-O 2 CCH 3 ) 3 -{Zn(HO 2 CCH 3 )}] (2), and [{Zn(κ 3 -bpzbdeape)}(μ-O 2 CCH 3 ) 3 {Zn(HO 2 CCH 3 )}] (3) in excellent yields. The molecular structure of these compounds was determined spectroscopically and confirmed by X-ray diffraction analysis. Zinc acetate complexes 1−3 were screened as catalysts for the copolymerization of cyclohexene oxide and CO 2 to produce poly(cyclohexene)carbonate, and complex 3 was found to be the most active catalyst for this process in the absence of a cocatalyst. Furthermore, the terpolymerization of cyclohexene oxide, phthalic anhydride, and CO 2 was studied using the combination of complex 3 and 4-dimethylaminopyridine as catalyst system yielding the corresponding polyester-polycarbonate materials.