Asymmetric Michael Addition Mediated by Novel Cinchona Alkaloid-Derived Bifunctional Catalysts Containing Sulfonamides

Asymmetric organocatalytic decarboxylative Mannich reaction using β-keto acids: A new protocol for the synthesis of chiral β-amino ketones

The first decarboxylative Mannich reaction employing β-keto acids, catalyzed by cinchonine-derived bifunctional thiourea catalyst has been described. The desired β-amino ketones were obtained in excellent yields and with moderate to good enantioselectivities.

Observation of neighboring ortho-hydroxyl group participation in organocatalytic asymmetric sequential Michael-lactonization reactions: synthesis of highly substituted chiral spirodihydrocoumarins

A general approach to asymmetric synthesis of highly substituted spirodihydrocoumarins with a quaternary stereocenter was achieved through neighboring ortho-hydroxyl group induced sequential Michael-lactonization reactions on 2-(2-nitrovinyl)phenols with alkyl cyclopentanone-2-carboxylates in the presence of a catalytic amount of quinine-NH-thiourea followed by p-TSA.

Enantioselective Morita-Baylis-Hillman reaction of isatins with acrylates: facile creation of 3-hydroxy-2-oxindoles

The first tertiary amine catalyzed enantioselective Morita-Baylis-Hillman (MBH) reaction of isatins with acrylates has been demonstrated, allowing asymmetric synthesis of biologically significant 3-substituted-3-hydroxy-2-oxindoles in good yields and with excellent enantioselectivities. The C6'-OH group of β-isocupreidine (β-ICD) is believed to facilitate the key proton transfer step in the MBH reaction, via an intramolecular proton relay process.

Proline Sulfonamide-Based Organocatalysis: Better Late than Never

The history of proline sulfonamides for use in catalyzing highly enantioselective and diastereoselective C-C bond forming reactions is described. Highlighted is the development of N-(p-dodecylphenylsulfonyl)-2-pyrrolidinecarboxamide ("Hua Cat") and N-(carboxy-p-dodecylphenylsulfonyl)-2-pyrrolidinecarboxamide ("Hua Cat-II") by Yang and Carter. Specific reactions covered include the aldol reaction, Mannich reaction, formal aza-Diels-Alder reaction, tandem Michael/Mannich reaction and Yamada-Otani reaction. The ability of proline aryl sulfonamides to construct all-carbon quaternary stereocenters in high enantioselectivity and diastereoselectivity is a notable feature of the reported work. The practicality of this chemistry for large scale and industrial applications is also included. Finally, a discussion of the future directions of proline sulfonamide organocatalysis is provided.

Asymmetric organocatalytic Michael addition of anthrone to enone

Catalyzed by the bifunctional tertiary amino-thiourea organocatalyst derived from epicinchona alkaloid, the asymmetric Michael addition of anthrone to enone was achieved in high yield with excellent enantioselectivity.

Organocatalytic Michael addition of 1,3-dicarbonyl indane compounds to nitrostyrenes

To map out the efficient organocatalyst requirements in the Michael addition of 1,3-dicarbonyl indane compounds to nitrostyrenes, a dozen different amino organocatalysts containing a p-toluenesulfonyl group (Ts) have been evaluated; excellent enantio-selectivities (up to er 92:8) were obtained with a primary amine-based Ts-DPEN catalyst and a plausible catalytic reaction mechanism was proposed on the basis of the experimental results.