Mechanochemical Synthesis of Substituted 4H-3,1-Benzoxazin-4-ones, 2-Aminobenzoxazin-4-ones, and 2-Amino-4H-3,1-benzothiazin-4-ones Mediated by 2,4,6-Trichloro-1,3,5-triazine and Triphenylphosphine

A mild and convenient approach for the synthesis of 2-substituted 4H-3,1-benzoxazin-4-ones, 2-aminobenzoxazin-4-ones, and 2-amino-4H-3,1-benzothiazin-4-ones under solvent-assisted grinding is reported. In the presence of 2,4,6-trichloro-1,3,5-triazine and catalytic triphenylphosphine, cyclodehydration of N-substituted anthranilic acid derivatives proceeded rapidly within minutes at room temperature. The products were also obtained in good to excellent yields by using minimal amounts of solvent and inexpensive reagents.