Spontaneous Cyclization of -Diiminonaphthalenes Leading to the Formation of Benzo[]isoquinolines and Stable Benzo[]isoquinoliniums.

The interaction of -dilithionaphthalenes with organic cyanides was studied. Instead of the expected -diimines, the reaction leads to the formation of three types of benzo[]isoquinolines. Treatment of unsubstituted 1,8-dilithionaphthalene with aromatic nitriles results in the formation of 1-amino-1,3-diaryl-1-benzo[]isoquinolines. In contrast, 4,5-dilithio-1,8-bis(dimethylamino)naphthalene gives an aromatic isoquinolonium cation via elimination of ammonia under the same condition. Upon treatment with -butylcyanide, both dilithionaphthalenes undergo a transformation to 1-amino-3,4-di--butyl-4-benzo[]isoquinolines. The observed reactivity was supported by quantum chemical calculations.