Direct Synthesis of Z, Boc, Fmoc, Alloc[ddot] Derivatives of 5-Aminooxazoles Starting from Acylamino Acids and Chlorosulfonylcarbamates

Abstract

A one-step synthesis of 5-oxazolecarbamates 1–11 can be easily carried out starting from N-acetylated and benzoylated aminoacids such as Gly, Ala, Leu, Phe, and chlorosulfonyl carbamates, prepared in situ by addition of alcohols on chlorosulfonyl isocyanate (CSI). The structure of the compounds was confirmed by X-Ray crystallography. A subsequent exocyclic N-alkylation gave substituted 12–18 derivatives. Carbamate cleavage gave by spontaneous reopening substituted N-acylaminoamides, in excellent yields.