Enantioselective Povarov Reactions: An Update of a Powerful Catalytic Synthetic Methodology

The enantioselective Povarov reaction is one of the most powerful synthetic strategy to synthesize chiral, highly functionalized 1,2,3,4-tetrahydroquinolines. The present Minireview aims to collect the most significant successful examples of highly efficient enantioselective catalytic protocols for this reaction, since 2014. A comprehensive discussion of different catalytic strategies employed in recent years to realize the enantioselective Povarov reaction is provided; the use of chiral phosphoric acids, thio(urea) and proline derivatives, as well as transition metal complexes will be presented. Additionally, this Minireview critically discusses the intriguing and yet obscure mechanistic pathways of this well-known reaction, the controversial dispute between a concerted or a polar two-step process.