Carbon‐13 nuclear magnetic resonance spectra of N‐substituted 2‐amino‐4H‐3,1‐benzoxazin‐4‐ones and 3‐substituted 2,4‐(1H,3H)quinazolinediones

Abstract 13C chemical shifts of nine N‐substituted 2‐amino‐4H‐3,1‐benzoxazin‐4‐ones, the isomeric 3‐substituted 2,4‐(1H,3H)quinazolinediones, and the parent compounds of the two series are reported. Support is provided for the endocyclic position of the C=N bond in the former series of compounds.