Synthesis and thermolysis of 5-azido-4-formyloxazoles

Abstract

5-Azidooxazole-4-carbaldehydes 5a–c have been prepared from the corresponding chloro aldehydes and found to be unstable in solution at room temperature. Whereas the phenyl derivative 5a′decomposed with loss of nitrogen and formation of the imine 6 which was trapped with 2,3-dimethylbutadiene, the isopropyl and tert-butyl derivatives 5b, ′c underwent a Cornforth rearrangement to give 4-azidocarbonyloxazoles 9b, c. Kinetic measurements revealed the following order of stability: 5a > 5c > 5b.