Synthesis of N-tert-butoxycarbonyl-DL-(±)-homo-tyrosine

Key words: 
• N-tert-butoxycarbonyl-DL-(±)-homo-tyrosine /
• synthesis /
• L-aspartic acid /
• Friedel-Crafts reaction /
• catalytic hydrogenation

Abstract: Objective To prepare N-tert-butoxycarbonyl-DL-(±)-homo-tyrosine(1),a key unusual amino acid and pharmaceutical intermediate for the total synthesis of novel peptides drug including cyclic or straight chain peptide. Methods Starting from L-aspartic acid(2),the target compound 1 was synthesized via 6 steps including N-methoxycarbonylation,intramolecular dehydration and anhydridation,Friedel-Crafts reaction with 2-chloroanisole,catalytic hydrogenation with 10% Pd-C,N-demethoxycarbonylation and demethylation with 48% HBr-HOAc followed by N-Butoxycarbonylation. Results Target compound 1 had been successfully synthesized in an overall yield of 49.7%.The structure of the target compound was confirmed by ESI-MS,¹H NMR and ¹C NMR. Conclusion The process developed has several advantages such as cheap materials,convenient workup and high yield.