Synthesis of quinoline derivatives from anilines and aldehydes catalyzed by Cp2ZrCl2 and recyclable Cp2ZrCl2/MCM-41 system

• Facile synthesis of quinolines using Cp2ZrCl2 as a new catalyst under mild condition.
• Yields increased by up to 15% by using Cp2ZrCl2/MCM-41 as catalyst vs. Cp2ZrCl2.
• Cp2ZrCl2/MCM-41 catalyst can be reused by simple recover via filtration in air.
• Reactions of various anilines with aldehydes gave good yields of the products.
• Reaction conditions such as solvent, temperatures and additives were optimized.

A facile method for the synthesis of quinoline derivatives using catalytic amount of Cp2ZrCl2 or Cp2ZrCl2 supported on MCM-41 (Cp2ZrCl2/MCM-41) in reaction of anilines and aldehydes is described. When Cp2ZrCl2/MCM-41 was used as catalyst, the yields of quinolines were enhanced by 5–15% compared with Cp2ZrCl2 as catalyst alone under the same reaction conditions. More importantly, Cp2ZrCl2/MCM-41 catalyst can be reused at least thrice by simple recover via filtration in air. Moreover, both Cp2ZrCl2 and Cp2ZrCl2/MCM-41 showed good catalytic activities to generate corresponding quinoline derivatives in moderate to good yields by varying the substituent of aniline and aldehyde. And the reaction conditions were optimized by studying the influences of reactant ratio, additives, solvent effect and reaction temperatures.

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