The Lewis acid B(C6F5)3 has been previously described as a catalyst for the reduction of carbonyls, ethers, and alcohol utilizing silanes as the stoichiometric reductant. In the area of biomass conversion, we have reported that the borane catalyst and the Brookhart (POCOP)IrH(acetone)+ catalyst are each competent at converting C6 biomass feedstocks like glucose into hydrocarbons like hexanes, provided that hyper-reactive secondary silanes like Et2SiH2 are utilized. If instead of secondary silanes, tertiary silanes are utilized, the reactions are considerably more sluggish, but also more more selective. We have taken advantage of this feature to carry out a number of partial reductions of glucose-like materials to convert them in to high-value partially oxygenated materials that are otherwise difficult to access. One example of such a process is the 1,6-reduction of glucitol (below). I will describe alternative applications of this principle for the synthesis of other compounds, many of which are difficult to synthesize. In addition to synthetic studies, mechanistic investigations on the nature of the intermediates and the comparative rates of 1° and 2° reductions will be discussed.

Borane catalyzed selective deoxygenation of carbohydrate biomass

249th National Meeting (2015)

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