Two mutually complementary synthetic approaches towards 3-substituted 3,4-disubstituted and 1-(2-pyridyl)-substituted isoquinolines

Two mutually complementary synthetic approaches towards 3- and 3,4-disubstituted 1-(2-pyridyl) isoquinolines were studied. The aryne-based method was successfully used for the obtaining of the corresponding the 3-cyano-1-(2-pyridyl)isoquinolines in one step/pot reaction, while it is unacceptable for the obtaining of other 1-(2-pyridyl)isoquinolines. The enamine-based approach was successfully applied for the synthesis of other 1-(2-pyridyl)isoquinolines, while it was  unacceptable for the obtaining of  3-cyano-1-(2-pyridyl)isoquinolines.