From Surprising Solvothermal Reaction to Uncommon Zinc(II)-Catalyzed Aromatic C–H Activation Reaction for Direct Nitroquinoline Synthesis

In this work, we first found a surprising
solvothermal reaction
for direct dinitration of quinoline derivative. To explore the application
in direct nitroquinoline synthesis, this reaction was subsequently
modified as an equivalent reaction in a Schlenk tube. More significantly,
after a constant attempt, nitrated derivative was obtained in optimized
condition with a zinc­(II) sulfate catalyst, where some substrates
with strong electron-withdrawing group were first nitrated by a directly
catalyzed condition. This new zinc­(II)-catalyzed aromatic C–H
activation reaction is the first example of direct dinitration by
a single catalyst, which will be a new facile and environmentally
friendly strategy to access synthetically useful nitroquinoline derivative.