New Findings on the Cerium(IV) Ammonium Nitrate Catalyzed Povarov Reaction: Stereoselective Synthesis of 4-Alkoxy-2-aryl-1,2,3,4-tetrahydroquinoline Derivatives

2008/03/06 by J. Menéndez, J. Carlos Menéndez, Vellaisamy Sridharan +1
Chemistry · #Asymmetric Synthesis and Catalysis #Chemical Synthesis and Reactions #Oxidative Organic Chemistry Reactions

paper · doi:10.1055/s-2008-1032126

Abstract

Cerium(IV) ammonium nitrate catalyzes the three-component, imino Diels-Alder (Povarov) reaction between anilines, aromatic aldehydes, and acyclic vinyl ethers, giving cis-4-alkoxy-2-aryl-1,2,3,4-tetrahydroquinolines with almost complete diastereoselectivity. The corresponding reaction starting from cyclic vinyl ethers gave the two possible diastereomers, with the endo-compound as the major product. This stereochemical outcome is explained through a stepwise mechanism for the imino Diels-Alder reaction, and this mechanism was subsequently proved by trapping the putative oxonium intermediate in the presence of ethanol.

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