3-Hydroquinolylquinolines and Bisquinolyl-annelated Oxepin as Unexpected Products from the Reaction of p-Benzoquinone and N-Acetyl-1,4-dihydroquinolines

4-Substituted N-acyl-1,4-dihydroquinolines (la, b) have been yielded by regioselective 4-arylation/alkylation via quinolinium intermediates. Acid-catalysed reaction of la, b with p-benzoquinone leads to unexpected 3-hydroquinolylquinolines (5a, b). The structure of compounds (5a, b) has been confirmed by spectroscopical data and additionally by formation of both O-acetyl derivatives (7a, b). Bisquinolyl-annelated oxepin (9a) was found as side product. Formation and stereochemistry of the spectroscopically characterized compound (9a) are discussed.