An investigation of the reaction of 2-aminobenzaldehyde derivatives with conjugated nitro-olefins: an easy and efficient synthesis of 3-nitro-1,2-dihydroquinolines and 3-nitroquinolines.

2-Aryl-3-nitro-1,2-dihydroquinolines 3 were prepared from the reaction of beta-nitrostyrenes 2 and 2-aminobenzaldehyde 1 in the presence of DABCO. Not only beta-nitrostyrenes but other alkyl nitro olefins also can be used in this reaction as well. When DDQ or silica gel was added to a solution of 3-nitro-1,2-dihydroquinolines 3, 3-nitro-2-substituted-quinolines 4 were obtained. When 2-aminobenzaldehyde derivatives 7 and 12 were reacted with beta-nitrostyrenes 2, unique rearrangement products were produced.