Synthesis of Pyrimidine Fused Quinolines by Ligand-Free Copper-Catalyzed Domino Reactions

Herein, we report
two novel methods for the synthesis of pyrimidine
fused quinolines using a one-pot C–C and C–N bond forming
strategy from the reaction of 6-aminouracils with 2-bromobenzaldehydes
or 2-bromobenzyl bromide derivatives in the presence of 10 mol % CuCl2 without using any ligand. The reaction of 2-bromobenzaldehyde
or its derivatives with 6-aminouracils in the presence of K2CO3 as base and a catalytic amount of CuCl2 in DMF medium under microwave heating conditions provides corresponding
pyrimidine fused quinoline derivatives in good yields within 30 min.
Alternatively, pyrimidine fused quinoline derivatives have been synthesized
from the reaction of 2-bromobenzyl bromides with 6-aminouracil derivatives
in the presence of molecular oxygen, CuCl2 (10 mol %),
and K2CO3 as base in DMF under reflux conditions.
Structures of all the products were unambiguously confirmed by spectroscopic
techniques and by recording single crystal XRD of 3a.