Three-Component One-Pot Approach to Highly Efficient and Sustainable Synthesis of the Functionalized Quinolones via Linear/Branched Domino Protocols, Key Synthetic Methods for the Floxacin of Quinolone Drugs

The development of a clear chemical
process to produce diverse
value-added chemicals from low-cost raw materials is a particularly
attractive concept and represents a considerable challenge in sustainable
organic synthesis. Herein, two highly efficient and clear methods
for the synthesis of quinolone derivatives based on a linear/branched
domino protocol under sustainable conditions were established. The
main advantages of these protocols are the simple experimental procedure,
high bond-forming efficiency, inexpensive readily available starting
materials, moderate to excellent yields with good functional group
compatibility, and nonchromatographic purification, which render these
methods particularly attractive for the sustainable preparation of
biologically and medicinally interesting molecules. To demonstrate
the practical utility of our protocol, existing pharmaceutical sarafloxacin
was successfully synthesized. Furthermore, a postulated reaction pathway
including condensation reaction/nucleophilic aromatic substitution/Friedel–Crafts
reaction for these domino reactions is also discussed.