A facile one-pot synthesis of N α-urethane protected 3-amino alkyl isoxazole-5-carboxylic acids and their utility for the preparation of isoxazole-linked peptidomimetics

Cu(I) catalyzed 3+2 cycloaddition of in situ generated N α-Fmoc/Boc/Z-protected amino alkyl nitrile oxide with propiolic acid has led to a new class of 3,5-disubstituted isoxazole-bearing amino acid derivatives. The click chemistry protocol described herein is efficient in furnishing the isoxazole embedded amino acids. These unnatural synthons were subjected to chain extension on N- as well as C-termini to obtain 3,5-disubstituted isoxazole bearing di and tripeptidomimetics. © Springer Science+Business Media, LLC 2011