Synthesis of Furo[3, 2-g][1, 4]Benzoxazin-3-ones, New Psoralen Isosters

Furobenzoxazin-3-one, a new tricyclic nucleus, was synthesised in two different and straigtforward routes: the first route consisted of condensing a furan ring onto a preconstituted 1,4-benzoxazinone nucleus, and the other in condensing a 1,4-oxazine ring onto the appropriate benzofuran system obtained from coumarin by ring contraction.