Spinning Sugar Into Hydrocarbons

In some sweet synthetic work, chemists at the University of California, Berkeley, have found a mild method for converting sugars and sugar alcohols into aromatic compounds and polyenes, respectively (Angew. Chem. Int. Ed., DOI: 10.1002/anie.201203877). The deoxydehydration reaction, developed by F. Dean Toste and Mika Shiramizu, could be used to convert saccharides, the major component of cellulosic biomass, into commodity chemicals and fuels. Although the deoxydehydration reaction has been used to pluck oxygen atoms off of diols and epoxides, getting the reaction to strip down polyols had been problematic. Toste and Shiramizu discovered that a methyltrioxorhenium catalyst could do the job efficiently when an alcohol, such as 3-pentanol, was used as a reductant. For example, using this protocol, they transformed the six-carbon sugar alcohol d-sorbitol into hexatriene—a possible feedstock for polymers. And when the chemists used sugars in the reaction, followed by dehydration, they were able to generate aromatic compounds, such as furan, benzene, and phenol. Future plans include boosting the reaction’s efficiency, applying the transformation to polysaccharides, and immobilizing and recycling the catalyst.