Metal-free iodine(iii)-promoted synthesis of 2,5-diaryloxazoles
A nonmetal-catalyzed oxidative cyclization to achieve 2,5-disubstituted oxazoles from inexpensive and readily available substituted chalcone, (diacetoxyiodo)benzene (PIDA) and ammonium acetate (NH4OAc) at room temperature is described. The reaction forms a variety of 2,5-diaryloxazoles in good to excellent yields with broad substrate scope under mild conditions without the requirement of ligands and additional bases.
One-pot conversion of amino acids into 2,5-disubstituted oxazoles: No metals needed
2,5-Disubstituted oxazoles with a variety of alkyl and aryl groups are efficiently formed from N-acylamino acids, by a one-pot radical decarboxylation- oxidation-enolization and iodine-promoted cyclization process. Remarkably, the reaction takes place under mild conditions, and no metal catalysis is needed. The process can be useful for the direct modification of small peptides.