The Synthesis of Some Chiral 2-Aminoalkyloxazole-4-carboxylates from Isoxazol-5(2H)-ones

Abstract

Ethyl 4-methyl-5-oxo-2,5-dihydroisoxazole-3-carboxylate can be N-acylated by a number of natural and synthetic phthalimidylamino acids in the presence of carbodiimides. The N-acylated products form the corresponding oxazoles smoothly when irradiated at 300 nm in acetone. Removal of the phthalimido protecting group then gives 2-aminoalkyloxazole-4-carboxylate esters in good overall yields, and without significant racemization at any step.