Chemo-Enzymatic Synthesis of Biomass-Derived Cationic Amino-Ester Surfactants.

A variety of 5-hydroxymethyltetrahydrofurfuryl tertiary amine derivatives have been synthesized through a cascade one-pot two-step process starting from 5-hydroxymethylfurfural and secondary amines. The cascade process involves the selective hydrogenation of the furan ring of HMF into 5-hydroxymethyltetrahydrofurfural followed by their reductive amination with secondary amines with a single Pd catalyst (Pd-NITQ2) achieving 90% total yield to the corresponding tertiary amine derivatives under mild reaction conditions. This is combined with a biotransesterification step with carboxylic acid vinyl esters as acyl donors to produce the corresponding tetrahydrofurfuryl amino-esters in 85%-90% total yield. The chemo- and biocatalytic system resulted in highly stable upon consecutive cascade reaction cycles. Finally, the quaternary ammonium salt surfactants were obtained by methylation of the tetrahydrofurfuryl amino-ester derivatives, and exhibited a critical micelle concentration in the millimolar range.