The synthesis of 2H-pyrido[3,4-c][1,2]benzoxazine-2,4(3H)-diones from 6-oxo-6H-1,2-oxazine-3-carboxylates

A simple procedure was developed for the synthesis of 2H-pyrido[3,4-c][1,2]benzoxazine-2,4(3H)-diones by the treatment of o-fluorophenyl-substituted 6-oxo-6H-1,2-oxazine-3-carboxylates with primary amines. The reaction proceeded according to the mechanism previously described for the formation of 3-(hydroxyimino)pyridine-2,6-diones followed by intramolecular nucleophilic substitution involving the hydroxyimino group to form the 1,2-oxazine ring.

Automated summary

A simple procedure was developed to synthesize 2H-pyrido[3,4-c][1,2]benzoxazine-2,4(3H)-diones from o-fluorophenyl-substituted 6-oxo-6H-1,2-oxazine-3-carboxylates using primary amines. The reaction followed a previously described mechanism for the formation of 3-(hydroxyimino)pyridine-2,6-diones, followed by intramolecular nucleophilic substitution to form the 1,2-oxazine ring.