First Use of HEH in Oxazine Synthesis: Hydroxy-Substituted 2H-1,4-Benzoxazine Derivatives.

The synthesis of 2H-1,4-benzoxazine derivatives from 1,2-epoxy-3-(2-nitroaryloxy)propanes in the presence of Hantzsch 1,4-dihydropyridine (HEH) and Pd/C as a catalyst was achieved. The nitro group was reduced before the epoxide functionality, leading to attack of the amino group on the epoxide moiety in a 6-exofashion. By introducing a methyl group at the I-position, the 7-endo ring-closed product could also be formed.