Sequential Ruthenium Catalysis for Olefin Isomerization and Oxidation: Application to the Synthesis of Unusual Amino Acids

How can you use a
ruthenium isomerization catalyst twice? A ruthenium-catalyzed
sequence for the formal two-carbon scission of allyl groups to carboxylic
acids has been developed. The reaction includes an initial isomerization
step using commercially available ruthenium catalysts followed by in situ transformation of the complex to a metal-oxo species,
which is capable of catalyzing subsequent oxidation reactions. The
method enables enantioselective syntheses of challenging α-tri-
and tetrasubstituted α-amino acids including an expedient total
synthesis of the antiepileptic drug levetiracetam.