A solvent-free method for making dioxolane and dioxane from the biorenewables glycerol and furfural catalyzed by oxorhenium(V) oxazoline.

Low catalyst loading of a cationic oxorhenium(V) oxazoline complex, [2-(2'-hydroxyphenyl)-2-oxazolinato(-2)]oxorhenium(v), condenses diols and aldehydes to give 1,3-dioxolanes in excellent yields under neat conditions and reasonably mild temperatures. The reaction is applicable to biomass-derived furfural and glycerol. The resulting cyclic acetals may find use as value-added chemicals and/or oxygenate fuel additives. Differences in the stereoselectivity of the reaction for epoxides versus diols provide insight into the reaction mechanism.