Cyelisation of arylcarboxamidouracils. Synthesis of a new 4H‐3,1‐benz‐oxazin‐4‐one. Use of mass spectrometry as a probe

The action of acetic anhydride on an anthranylcarboxamidouraeil led to a new 2‐substituted 4H‐3,1‐benzoxazin‐4‐one with potential analgesic activity. Mass spectrometry has been used as a method lor structure confirmation and several fragmentation pathways were proposed. Furthermore, an additional probe was given by opening of the lactonic ring submitted to the action of aliphatic and aromatic primary amines.