Synthesis of highly functionalized oxazines by Vilsmeier cyclization of amidoalkyl naphthols

The intramolecular cyclization of amidoalkyl naphthols by Vilsmeier reagent produced 1,3-oxazines. The Vilsmeier reagent (chloromethylenedimethylammonium chloride) has been used as an efficient and cheap acid activator for the one-step synthesis of oxazine derivatives. A mechanism involving sequential haloformylation and intramolecular nucleophilic cyclization is proposed.