Jiangrine-like scaffolds from biorenewable platforms

Practical and scalable enantioselective synthesis of (+)-majoranolide from Cyrene

A two-step enantioselective gram scale synthesis of the Persea derived γ-lactones (+)-majoranolide and (+)-majoranolide B has been achieved. The sequence uses the amine promoted crossed condensation of the biorenewable synthon Cyrene with aliphatic aldehydes followed by a Baeyer-Villiger oxidation. Comparison of optical rotation data with the natural products established the absolute configuration of the natural product series, and this work represents the first synthesis of these alkylidene natural products.

Catalytic deep eutectic solvent for levoglucosenone production by pyrolysis of cellulose

This work presents the selective production of the versatile bio-based platform levoglucosenone (LGO) using deep eutectic solvents (DESs) as catalysts during cellulose pyrolysis. Among 18 types of DESs examined, those containing p-toluenesulfonic acid as a hydrogen bond donor possessed the requisite thermal stability for use in the pyrolysis of cellulose. When those DESs were combined with cellulose, the pyrolysis temperature could be reduced which led to greater selectivity for LGO, the highest yield being 41.5% on a carbon basis. Because of their thermal stability, the DESs could be recovered from the pyrolysis residue and reused. The DESs recovery reached 97.9% in the pyrolysis at a low temperature with the LGO yield of 14.0%. Thus, DES-assisted cellulose pyrolysis is a promising methodology for LGO production.