A novel high-yield synthesis of aminoacyl p-nitroanilines and aminoacyl 7-amino-4-methylcoumarins: Important synthons for the synthesis of chromogenic/fluorogenic protease substrates

• Xinghua Wu,
• Yu Chen,
• Herve Aloysius and
• Longqin Hu

Beilstein J. Org. Chem. 2011, 7, 1030–1035, doi:10.3762/bjoc.7.117

• -amino-4-methylcoumarin; p-nitroaniline; proteolytic substrate; selenocarboxylate/azide amidation; synthon; Introduction Chromogenic and fluorogenic amino acid/peptide conjugates are widely used as substrates in enzyme assays for protease activity and specificity [1]. Proteolytic cleavage of the amino

• as problematic as p-nitroaniline due to the low nucleophilicity of the 7-aromatic amino group. Thus, the method developed for the synthesis of aminoacyl-pNAs could also be applied to the synthesis of aminoacyl-AMC derivatives. We previously described a novel selenocarboxylate/azide amidation reaction

• [18][19] and its application to directly couple amino acids with azides [20]. We demonstrated that our selenocarboxylate/azide amidation does not involve reduction of the azide to amine and subsequent standard coupling reaction [18][19]. We also demonstrated that the selenocarboxylate/azide amidation