Tetrahedron Letters,Vol.25,No.21,pp 2287-2288,1984 0040-4039/84 $3.00 + .OO ... ARYL SUBSTITUENT EFFECTS UPON THE THERMAL ISOMERIZATION OF N-ALKYL OXAZIRIDINES TO NITRONES ... Derek R. Boyd*, Peter B. Coulter, W. James Hamilton Department of Chemistry, Queen's University of Belfast, Belfast BT9 5AG, Northern Ireland * and W. Brian Jennings , and Valerie E. Wilson, Department of Chemistry, University of Birmingham, Birmingham B15 2TT, England