From Three- to Six-Membered Heterocycles Bearing a Quaternary Stereocenter: an Asymmetric Organocatalytic Approach.

The development of procedures useful to form quaternary stereocenters stands out as a highly challenging task in asymmetric synthesis. With the arrival of organocatalysis, different activation strategies became available to pursue this intriguing target, thus leading to notable advancements of the area. In this account, our achievements, spanning over a decade, on asymmetric methodologies to access novel three-, five-, six-membered heterocycles, including spiro compounds bearing quaternary stereocenters, will be highlighted. The Michael addition reaction has been often exploited to trigger cascade reactions, using organocatalysts mostly derived from Cinchona alkaloids, and operating under non-covalent activation of the reagents. Further manipulations of the enantioenriched heterocycles, attested them as useful compounds to prepare functionalized building blocks.