Regiospecific Nitration of Quinoline and Isoquinoline through the Reissert Compounds

Regiospecific nitration of quinoline and isoquinoline was achieved via the Reissert compounds by treatment with acetyl nitrate. Nitration of l-benzoyI-2-cyanoquinoline (3) afforded the 3-nitro derivative, which was converted to 3-nitroquinoline by hydrolysis with concentrated HC1. Meanwhile, 2-benzoyl-l-cyano-l,2-dihydroisoquinoline (4) was converted ultimately into 4-nitroisoquinoline-l-carboxylic acid (10) via 4-nitro-l-cyanoisoquinoline by the same procedure. A novel method for introducing a nitro group at the -position of a heterocyclic moiety has thus been developed. Crystal structure determinations and molecular orbital calculations of the Reissert compounds, are consistent with the regiospecific nitration.