Sunday, May 4, 2008
4-55

Synthetic Applications of the Ferrier Reaction in Organometallic and Carbohydrate Chemistry

Nathan C. Tice and Joseph J. Bozell. Forest Products Center – Biomass Chemistry Laboratories, University of Tennessee, 2506 Jacob Drive, Knoxville, TN 37996

In contrast to nonrenewable carbon feedstocks, renewable biomass feedstocks face a lack of chemical transformations, thus limiting their commercial application. For example, nanoscale materials are well known in biological and physical systems, e.g., carbon nanotubes, but there is relatively little exploration is self-assembled structures incorporating simple carbohydrates. Similarly, catalytic production of fuels, chemicals, materials, etc. on an industrial scale from fossil fuels is accomplished with transition metal complexes, yet broad based catalytic processes have yet to be developed for carbohydrates. This paper describes the synthesis and reactivity of some carbohydrate-based self-assembled structures and carbohydrate-transition metal complexes prepared using the Ferrier reaction. In conventional organic systems, the Ferrier reaction of simple sugar derivatives (glucal, xylal, galactal) with alkyl diols and I2 affords glycal-based bolaamphiphiles (bolaforms). These bolaforms undergo self-assembly in dioxane/water to give tubular structures. Comparison in the solid state of the glycal bolaforms with glycosamide bolaforms show that the packing motif is primarily driven by the stereochemistry at the pyranose ring. With organometallic systems, the Ferrier reaction of triacetylglucal (TAG), a Lewis acid (BF3 etherate, I2), and organometallic nucleophiles give metal-carbohydrate complexes. The reaction of KFe(CO)2Cp (KFp) with TAG affords a highly unstable complex. In contrast, the analogous Ferrier reaction employing Li[Mn(CO)5] and either TAG or the corresponding diacetylxylal and triacetylgalactal affords relatively stable complexes. We will also present the reactivity of metal nucleophiles with glycosyl halides, as well as attempted formation of olefin complexes from either a sigma precursor or direct metallation employing Fe2(CO)9 or an Fe-isobutenyl complex.