Preparation of diastereomeric 5,8-methanobenzoxazino[2,1-b]-1,3-benzoxazin-4-ones and 5,8-metaanobenzoxazino[2,3-b]-1,3-benzoxazin-4-ones by reaction of norbornane/ene-condensed dihydro-1,3-oxazines with salicyl chloride - Stájer Géza (1991)