The stereoselective synthesis of meso-diaminopimelic
acid (meso-DAP), the key cross-linking amino acid
of the peptidoglycan cell wall layer in Gram-negative bacteria, and
its biological precursor, l,l-DAP, is described.
The key step involved stereoselective reduction of a common enone-derived
amino acid by substrate- or reagent-based control. Overman rearrangement
of the resulting allylic alcohols, concurrent alkene hydrogenation
and trichloroacetamide reduction, and subsequent ruthenium-catalyzed
arene oxidation completed the synthesis of each stereoisomer. The
synthetic utility of this approach was demonstrated with the efficient
preparation of an l,l-DAP-derived dipeptide.