Synthesis of Enantiomerically Pure Lignin Dimer Models for Catalytic Selectivity Studies

A series
of highly enantioselective transformations, such as the
Sharpless asymmetric epoxidation and Jacobsen hydrolytic kinetic resolution,
were utilized to achieve the complete stereoselective synthesis of
β-O-4 lignin dimer models containing the S, G, and H subunits
with excellent ee (>99%) and moderate to high
yields.
This unprecedented synthetic method can be exploited for enzymatic,
microbial, and chemical investigations into lignin’s degradation
and depolymerization as related to its stereochemical constitution.
Preliminary degradation studies using enantiopure Co­(salen) catalysts
are also reported.