Heterocyclic N-oxides. Part V. The base-catalysed cyclisation of N-substituted o-nitrobenzamides to 1,4-dihydro-1-hydroxy-4-oxoquinazolines

Abstract

Derivatives of 1,4-dihydro-1-hydroxy-4-oxoquinazoline are formed, together with benzoic acid, when o-nitrobenzamidoacetonitrile is warmed with alcoholic solutions of sodium alkoxides. The ketone ω-(o-nitrobenzamido)-acetophenone, heated under reflux with ethanolic sodium ethoxide gives the N-hydroxy-compound 1,4-dihydro-1-hydroxy-4-oxoquinazoline, whereas in warm aqueous ethanolic alkali it affords 2-benzoyl-3,4-dihydro-4-oxo-quinazoline. The cyclic hydroxamic acids 1,2,3,4-tetrahydro-1-hydroxy-2,4-dioxoquinazoline and 1,2,3,4-tetrahydro-1-hydroxy-2,3-dioxoquinoxaline decompose at their melting points yielding the reduced compounds (H for OH at position-1).