Primary Amine/(+)-CSA Salt-Promoted Organocatalytic Conjugate Addition of Nitro Esters to Enones

The combination of 9-amino-9-deoxy-epi-cinchonine and (+)-CSA resulted in a novel primary amine-based organocatalyst for effective iminium activation of α,β-unsaturated ketones. Such a catalytic system could catalyze the conjugate addition of nitroacetate to enones in a highly enantioselective manner, affording the desired adducts in high yields and with up to 99% ee

Facile Synthesis of Bicyclic Amidines and Imidazolines from 1,2-Diamines

A facile synthesis of chiral bicyclic amidines and imidazolines from readily available 1,2-diamines has been developed. The reported synthetic strategy relies on an intramolecular cyclization which involves a carboxylic amide derived imidoyl chloride as a key intermediate and aniline serving as a leaving group

Enantioselective Conjugate Addition of Nitroalkanes to Vinyl Sulfone: An Organocatalytic Access to Chiral Amines

Organocatalytic asymmetric conjugate addition of nitroalkanes to vinyl sulfone mediated by cinchona alkaloid-derived thiourea catalyst afforded the desired Michael product with good enantioselectivity. The described method, in combination with ready desulfonation, represents a novel approach to access α-alkylated chiral amines

Organocatalytic Michael Addition of Aldehydes to Vinyl Sulfones: Enantioselective α-Alkylations of Aldehydes and Their Derivatives

Organocatalytic asymmetric Michael reaction of unmodified aldehydes to vinyl sulfones catalyzed by silylated biarylprolinol afforded the desired Michael products with exceptional enantioselectivity. The described enantioselective addition to vinyl sulfones, in combination with desulfonation, offers a unique, asymmetric entry to α-alkylated aldehydes and their derivatives

Asymmetric Synthesis of 2-Aryl-2,3-dihydro-4-quinolones via Bifunctional Thiourea-Mediated Intramolecular Cyclization

A novel asymmetric preparation of optically enriched 2-aryl-2,3-dihydroquinolin-4(1H)-ones has been developed. By installing a sulfonyl group on the nitrogen of the anilines and an ester function on the unsaturated ketones, an intramolecular organocatalytic cyclization took place readily in a stereoselective manner, resulting in the formation of dihydroquinolones with high enantioselectivity

Organocatalytic Asymmetric Aldol Reaction of Hydroxyacetone with β,γ-Unsaturated α-Keto Esters: Facile Access to Chiral Tertiary Alcohols

An efficient direct asymmetric aldol reaction between hydroxyacetone and β,γ-unsaturated α-keto esters has been successfully developed. In the presence of 9-amino-9-deoxy-epi-cinchonine and trifluoroacetic acid, the direct aldol reaction of O-protected hydroxyacetone proceeded in a highly enantioselective manner, affording the desired adducts containing a chiral tertiary alcohol in high yields and with excellent enantioselectivities. The aldol products obtained are valuable precursors for the synthesis of 2-substituted glycerol derivatives

Highly Enantioselective and Regioselective Substitution of Morita–Baylis–Hillman Carbonates with Nitroalkanes

A highly enantioselective and regioselective substitution reaction of the Morita–Baylis–Hillman (MBH) carbonates with nitroalkanes catalyzed by a quinidine-derived tertiary amine–thiourea catalyst has been developed. The described method, which is different from most organocatalytic allylic substitutions of the MBH adducts to date, represents a novel approach to regioselectively functionalize the MBH adducts

Asymmetric Allylic Alkylation of Isatin-Derived Morita–Baylis–Hillman Carbonates with Nitroalkanes

A stereoselective allylic alkylation of isatin-derived Morita–Baylis–Hillman (MBH) carbonates with nitroalkanes has been developed. In the presence of 10 mol % β-isocupreidine (β-ICD), 3,3′-disubstituted oxindoles were prepared with moderate diastereoselectivities and excellent enantioselectivities

Highly Enantioselective and Regioselective Substitution of Morita–Baylis–Hillman Carbonates with Nitroalkanes

A highly enantioselective and regioselective substitution reaction of the Morita–Baylis–Hillman (MBH) carbonates with nitroalkanes catalyzed by a quinidine-derived tertiary amine–thiourea catalyst has been developed. The described method, which is different from most organocatalytic allylic substitutions of the MBH adducts to date, represents a novel approach to regioselectively functionalize the MBH adducts

Highly Enantioselective Synthesis of 3,4-Dihydropyrans through a Phosphine-Catalyzed [4+2] Annulation of Allenones and β,γ-Unsaturated α‑Keto Esters

A phosphine-catalyzed novel [4+2] annulation process was devised employing allene ketones as C2 synthons and β,γ-unsaturated α-keto esters as C4 synthons. In the presence of an l-threonine-derived bifunctional phosphine, 3,4-dihydro­pyrans were obtained in high yields and with virtually perfect enantio­selectivities. The synthetic value of the dihydro­pyran motif was demonstrated by a concise preparation of an anti-hyper­cholesterol­emic agent