NITROGEN BRIDGEHEAD COMPOUNDS .85. SYNTHESIS AND REACTIVITY OF 3,4-DIHYDRO-1H,6H-[1,4]OXAZINO[3,4-B]QUINAZOLIN-6-ONES

3,4-Dihydro-1H,6H-[1,4]oxazino[3,4-b]quinazolin-6-one 3 and its 1-methyl and 1-hydroxy derivatives 8 and 13 were prepared by different routes. The active methylene group of compound 3 was reacted with electrohilic reagents (bromine, phenyldiazonium chloride, nitrous acid, a Vielsmeier-Haack reagent, aromatic aldehydes and diethyl oxalate) to yield 1-substituted-3,4-dihydro[1H,6H]-1,4-oxazino[3,4-b]quinazo-lin-6-ones. The reactivity of 1-hydroxy and 1-bromo derivatives 13 and 15 were also investigated in some reactions. The 3,4-dihydro-1H,6H-[1,4]oxazino[3,4-b]quinazolin-6-ones were characterized by means of uv, H-1 and C-13 nmr spectroscopy.