A Cp(tt)‐Based Trioxo‐Rhenium Catalyst for the Deoxydehydration of Diols and Polyols

Trioxo‐rhenium complexes are well known catalysts for the deoxydehydration (DODH) of vicinal diols (glycols). In this work, we report on the DODH of diols and biomass‐derived polyols using Cp(tt)ReO(3) as a new catalyst (Cp(tt)=1,3‐di‐tert‐butylcyclopentadienyl). The DODH reaction was optimized using 2 mol % of Cp(tt)ReO(3) and 3‐octanol as both reductant and solvent. The Cp(tt)ReO(3) catalyst exhibits an excellent activity for biomass‐derived polyols. Specifically, glycerol is almost quantitatively converted to allyl alcohol and mucic acid gives 75 % of muconates at 91 % conversion. In addition, the loading of Cp(tt)ReO(3) can be reduced to 0.1 mol % to achieve a turn‐over number as high as 900 per Re when using glycerol as substrate. Examination of DODH reaction profiles by NMR spectroscopy indicates that catalysis is related to Cp‐ligand release, which raises questions on the nature of the actual catalyst.