Regiospecific Nitration of Quinoline and isoquinoline through the Reissert Compounds

Regiospecific nitration of quinoline and isoquinoline was achieved via the Reissret compounds by treatment with acetyl nitrate. Nitration of 1-benzoyl-2-cyanoquinoline (3) afforded the 3-nitro derivative, which was converted to 3-nitroquinoline by hydrolysis with concentrated HCl. Meanwhile, 2-benzoyl-1-cyano-1, 2-dihydroisoquinoline (4) was converted ultimately into 4-nitroisoquinoline-1-carboxylic acid (10) via 4-nitro-1-cyanoisoquinoline by the same procedure. A novel method for introducing a nitro group at the β-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.