Lignol Cleavage by Pd/C Under Mild Conditions and Without Hydrogen: A Role for Benzylic CH Activation?

The cleavage of C-O bonds in lignin model compounds without hydrogen was developed using the commercially available Pd/C. Hydrogen donor solvents are helpful for this reaction through transfer hydrogenation, but not necessary. A redox neutral process that utilizes the internal hydrogen source for the cleavage is also possible. An initial mechanistic study indicates that the β-benzylic-H atom in the substrate plays a critical role and that the present system undergoes a process different from previous reports.