Acylation and Cyclization of N-Hydroxyisoureas by Phenyl Isocyanate

Article abstract of DOI:10.1002/ardp.19813140104

On adding phenyl isocyanate to the N-hydroxyisoureas 1 the O-carbamoyl derivatives 4 are obtained.They can undergo ring closure to yield Δ²-1,2,4-oxadiazolin-5-one (5a), the 3-imino-1,2,4-oxadiazolidin-5-ones 5b-5e or Δ³-1,2,4-oxadia