A concise and efficient concurrent synthesis of 6,11-dihydrodibenzo[ b , e ]azepines and 5,6,11,12-tetrahydrodibenzo[ b , f ]azocines and their conversion to 4-oxo-8,13-dihydro-4 H -benzo[5,6]azepino[3,2,1- ij ]quinoline-5-carboxylates and N -acetyl-5,6,11,12-tetrahydrodibenzo[ b , f ]azocines: synthetic sequence, spectroscopic characterization and the structures of two products