Chemoselectivity of 6-Bromo-2-methyl-3,1-benzoxazin-4-one towards Amines, Schiff Bases, and Azines

Article abstract of DOI:10.1007/BF00807415

6-Bromo-2-methyl-3,1-benzoxazin-4-one (1) undergoes an unusual cleavage at position 4 when it is allowed to react with o-phenylenediamine or anthranilic acid in dry benzene to give the corresponding compounds 2 5, respectively. The reaction of 1 with Schiff bases and azines results in the formation of the compounds 6a d and 8a, b, respectively. The reaction involves a cleavage of the Schiff base or the azine into its amine and arylidene moieties which are smoothly incorporated into 1 via nucleophilic attack of the amine at position 4 and condensation of the aldehyde with a reactive methyl group, at position 2 respectively. No displacement of the arylidene segment was observed.