HINDERED CAVITY-SHAPED N-OXIDES

The crystal structures of 1-hydroxy-5,6-dihydro-12-azabenz[a]anthracen e N-oxide (1), C17H13NO2, and 1-methoxy-5,6-dihydro-12-azabenz[a]anthr acene oxide (2), C18H15NO2, have been determined. In both (1) and (2), the 2-phenylquinoline N-oxide skeleton has been strengthened by a -CH 2-CH2- linkage through the 3- and 6'-positions. Moreover, in compound (1) a strong intramolecular O-H...O hydrogen bond is formed which acco unts for the fact that a more planar conformation of molecule (1) is o bserved compared with molecule (2). Modes of steric strain compensatio n in both (1) and (2) are discussed.