Platinum-Group-Metal-on-Carbon Catalyzed Dehydration of Tertiary Alcohols and its Application to the One-Pot Synthesis of Aromatics

Abstract

Catalytic dehydration of alcohols remains a challenge in organic synthesis, and olefin products are important synthetic precursors because of their high reactivity. Platinum-group-metal-on-carbon catalysts (such as Ru/C and Pd/C) are commercially available and widely utilized as heterogeneous, green, and sustainable catalysts in various organic reactions.However, examples of their application to the catalytic dehydration of alcohols have not been reported. Herein, we demonstrate the Ru/C-catalyzed dehydration of tertiary (tert) alcohols in toluene under thermal conditions. Ru/C also potentially exhibits oxidative activity. Therefore, a tandem reaction involving the Ru/C-catalyzed dehydration of tert-benzylic alcohols, a Diels-Alder reaction, and subsequent oxygen oxidation was developed to afford highly functionalized aromatic products. Additionally, a one-pot synthesis of biaryls from 1-arylcyclohexanols as tert-alcohol substrates was successfully developed via Pd/C-catalyzed dehdyration and subsequent dehydrogenation in H2O. These green and sustainable synthetic approaches based on novel heterogeneous dehydration methodologies are valuable for the construction of diverse functional materials.