Synthesis of beta-hydroxy-beta-(fluoronitrophenyl)alanines: vital components in the assembly of biologically active cyclic peptides.

[formula: see text] Numerous biologically active cyclic peptides, such as the antibiotic vancomycin, contain amino acid residues connected through side-chain biaryl or aryl-alkyl ether linkages. Nucleophilic aromatic substitution reactions have recently been shown to provide a general method for the formation of such ether linkages, and consequently the synthesis of functionalized fluoronitro-substituted aromatic amino acids is of great interest. Herein, a method for the stereospecific synthesis of 3-fluoro-4-nitro- and 4-fluoro-3-nitro-threo-beta-hydroxyphenylalanine is described.