Synthesis and stereochemistry of stereoisomeric 1,3-benzoxazino-1,3- and -3,1-benzoxazines

Partly saturated 3,1-benzoxazino1,2-c]1,3]benzoxazines and 1,3-benzoxazino3,2-c]1,3]benzoxazines were prepared in one-pot syntheses from different cyclic 1,3-aminoalcohols by treatment with salicylaldehyde or 5-bromosalicylaldehyde, followed by formaldehyde. The structures of tetracycles 3a and 5 were determined by means of X-ray diffraction.