Chiral Co(II) complex catalyzed asymmetric Michael reactions of β-ketoamides to nitroolefins and alkynones

The catalytic enantioselective Michael additions of cyclic β-ketoamides to nitroolefins and alkynones were accomplished in the presence of chiral N,N′-dioxide–Co(II) complexes. The desired adducts were obtained in high yields (up to 98%) with excellent enantioselectivities (up to 97% ee).     

Solvent free,fast and asymmetric Michael additions of ketones to nitroolefins using chiral pyrrolidine–pyridone conjugate bases as organocatalysts

New chiral organocatalysts are envisaged based on a pyrrolidine–pyridone conjugate and synthesized from commercially available proline employing standard protocols. These catalysts were found to be useful for asymmetric Michael additions of ketones to nitroolefins to afford the desired products in very good yields (up to 98%) with excellent diastereo- and enantioselectivities (>97:3 syn/anti and up to 98% ee) in very short reaction time compared with the existing reports.     

Doubly stereocontrolled asymmetric conjugate addition of acetylacetone to nitroolefins catalyzed by bifunctional tertiary amine-thiourea catalysts derived from both acyclic α-amino acids and carbohydrates

A novel class of easily preparative, cheap, and fine-tunable bifunctional chiral tertiary amine-thiourea organocatalysts have been developed by combining both acyclic diamines derived from acyclic α-amino acids and carbohydrates. These organocatalysts promoted the enantioselective conjugate addition of acetylacetone to various nitroolefins in good yields (up to 93%) with good enantioselectivities (up to 91% ee). The present research demonstrates the advantages of incorporating two stereocontrolling structures into a single catalyst. Notably, it offers a simple and convenient doubly stereocontrolled approach for the catalytic asymmetric synthesis of a chiral organic molecule.     

Copper-catalyzed enantioselective 1,4-conjugate addition of dialkylzinc reagents to α,β- and α,β,γ,δ-unsaturated ketones

An enantioselective Cu(II)-catalyzed conjugate addition of dialkylzinc reagents to α,β- or α,β,γ,δ-unsaturated ketones with chiral cyclohexane-based amidophosphine ligands was developed. With 2 mol% of Cu(OAc)₂·H₂O/L5, the conjugate addition of diethylzinc to α,β-unsaturated ketones was achieved in good-to-excellent yields (up to 98%) and high enantioselectivities (up to 92% ee). This catalytic system was shown to be efficient for the 1,4-conjugate addition of Et₂Zn to (2E,4E)-1,5-diphenylpenta-2,4-dien-1-one with 85% yield and 90% ee. Moreover, with 1 mol% of Cu(OTf)₂/L11, the conjugate addition of α,β,γ,δ-unsaturated ketones was accomplished with 1,4-regioselectivity, good yields (79–86%) and excellent enantioselectivities (up to 97% ee).     

Enantioselective synthesis of chiral sulfones by ir-catalyzed asymmetric hydrogenation: a facile approach to the preparation of chiral allylic and homoallylic compounds

A highly efficient and enantioselective Ir-catalyzed hydrogenation of unsaturated sulfones was developed. Chiral cyclic and acyclic sulfones were produced in excellent enantioselectivities (up to 98% ee). Coupled with the Ramberg-B?cklund rearrangement, this reaction offers a novel route to chiral allylic and homoallylic compounds in excellent enantioselectivities (up to 97% ee) and high yields (up to 94%).     

Highly efficient asymmetric Michael addition of aldehydes to nitroalkenes with 4,5-methano-l-proline as organocatalysts

The 4,5-methano-l-prolines were used as chiral organocatalysts in asymmetric Michael addition of aldehydes to nitroolefins. These proline-like catalysts are unique for their rigid bicyclic structure with a cyclopropane and two H atoms attached to the bridgehead C atoms lying on the same side of the ring. They therefore showed high efficiency in asymmetric Michael addition of aldehydes to nitroolefins. Under the optimal conditions, excellent diastereo- and enantioselectivities (up to 97/3 dr and 98% ee) were obtained in high yields for a series of aldehydes and nitroolefins using only 5 mol % catalyst loading. The methodology features easily available catalysts, high catalytic efficiency and environmentally friendly procedures.     

Chiral (thio)phosphorodiamides as excellent hydrogen bond donor catalysts in the asymmetric Michael addition of 2-hydroxy-1,4-naphthoquione to nitroolefins

A novel type of bidentate hydrogen bond donor catalysts based on (thio)phosphorodiamides catalophore has been developed for the asymmetric Michael addition of 2-hydroxy-1,4-naphthoquione to nitroolefins, affording the corresponding adducts in high yields with excellent level of enantioselectivities (97- >99% ee).     

First enantioselective organocatalytic conjugate addition of aldehydes to vinyl phosphonates

Chiral amines catalyze the enantioselective conjugate addition of aldehydes to vinyl phosphonates in high yields and with enantioselectivities up to 97% ee. This novel process provides synthetically useful chiral gamma-geminal phosphonate aldehydes which can be easily converted in a few steps into chiral beta-substituted vinyl phosphonates with conservation of the optical purity.     

Enantioselective Michael addition of 3-aryl-substituted oxindoles to methyl vinyl ketone catalyzed by a binaphthyl-modified bifunctional organocatalyst

The enantioselective conjugate addition reaction of 3-aryl-substituted oxindoles with methyl vinyl ketone promoted by binaphthyl-modified bifunctional organocatalysts was investigated. The corresponding Michael adducts, containing a quaternary center at the C3-position of the oxindoles, were generally obtained in high yields with excellent enantioselectivities (up to 91% ee).     

Chiral squaramide-catalyzed highly diastereo- and enantioselective direct Michael addition of nitroalkanes to nitroalkenes

An efficient highly diastereo- and enantioselective direct Michael addition of nitroalkanes to nitroalkenes catalyzed by chiral squaramide catalyst has been developed. This organocatalytic reaction with a low catalyst loading (2 mol%) proceeded well to afford synthetically useful 1,3-dinitro compounds in high yields with high diastereoselectivities (up to 95 : 5 dr) and excellent enantioselectivities (up to 97% ee).     

Enantioselective α-amination of branched aldehydes promoted by simple chiral primary amino acids

A series of simple chiral primary amino acids were first successfully applied to promote the enantioselective α-amination of branched aldehydes with azadicarboxylates and the desired adducts bearing quaternary stereogenic centers were obtained in excellent yields (up to 99%) and enantioselectivities (up to 97% ee).     

Highly enantioselective Friedel-Crafts reaction of indoles with 2-enoylpyridine 1-oxides catalyzed by chiral pyridine 2,6-bis(5',5'-diphenyloxazoline)-Cu(II) complexes

The catalytic enantioselective Friedel-Crafts reaction of indoles with 2-enoylpyridine 1-oxides has been studied in the presence of chiral pyridine 2,6-bis(5',5'-diphenyloxazoline)-Cu(II) complexes. The reaction furnished alkylated indoles in excellent yields (up to 97%) and enantioselectivities (up to 99% ee).     

A recyclable organocatalyst for asymmetric Michael addition of acetone to nitroolefins

Based on different chiral diamine skeletons, a series of bifunctional primary amine-thiophosphoramides were synthesized and screened as the catalysts for the asymmetric Michael addition of acetone to both aromatic and aliphatic nitroolefins. Under the catalysis of a thiophosphoramide derived from 1,2-diphenylethane-1,2-diamine, the corresponding adducts were obtained in high yields (up to >99%) with excellent enantioselectivities (97-99% ee) under mild reaction conditions. Moreover, the catalyst could be recovered via simple phase separation and reused at least five times without any loss of both catalytic activity and stereocontrol.     

Catalytic enantioselective arylation of aldehydes: boronic acids as a suitable source of transferable aryl groups

The catalytic enantioselective arylation of several aldehydes using boronic acids as the source of transferable aryl groups is described; the reaction is found to proceed in excellent yields and high enantioselectivities (up to 97% ee) in the presence of a chiral amino alcohol.     

Enantioselective Michael addition of anthrone to nitroalkenes catalyzed by bifunctional thiourea-tertiary amines

A highly bifunctional thiourea-tertiary amine-catalyzed enantioselective Michael addition reaction of anthrone to a wide variety of nitroalkenes has been developed, and the corresponding adducts were obtained smoothly in high yields (up to 97%) and good enantioselectivities (up to 94% ee).     

Asymmetric addition of alkynes to imines in water catalyzed with a recyclable Cu(I)–bis(oxazoline) and stearic acid system

Stearic acid and its zinc salt were used as additives in the enantioselective alkyne addition to imines catalyzed by copper(I)–bis(oxazoline) (box) in water. The reactions took place smoothly with good yields and high enantioselectivities (up to 97% ee). Good enantioselectivities were maintained in a catalyst recycle study.     

Diastereo- and enantioselective conjugate addition of 3-substituted oxindoles to nitroolefins catalyzed by a chiral Ni(OAc)2-diamine complex under mild conditions

A simple catalyst system assembled from an enantiomerically pure diamine ligand and Ni(OAc)(2) efficiently generates chiral metal enolates derived from 3-substituted oxindoles bearing an N-1 carbonyl group. The enolates smoothly undergo diastereo- and enantioselective conjugate addition to a wide range of nitroolefins under mild reaction conditions, furnishing 3,3-disubstituted oxindole products bearing two vicinal quaternary/tertiary stereocenters in 74-95% yields and 60:40 to 99:1 dr, 71-97% ee.     

Highly efficient asymmetric organocatalytic Michael addition of α,α-disubstituted aldehydes to nitroolefins under solvent-free conditions

A chiral pyrrolide-based diamine in combination with benzoic acid has been found to be an effective organocatalyst for Michael addition of α,α-disubstituted aldehydes with nitroolefins. The reaction provided the desired Michael products possessing all-carbon quaternary center with high yields (76–98%) and high levels of enantioselectivities (up to 97% ee) under solvent-free reaction conditions. The procedure presented is simple and makes this method suitable for practical use.     

Catalytic enantioselective synthesis of glutamic acid derivatives via tandem conjugate addition-elimination of activated allylic acetates under chiral PTC conditions

A new, general, and practical procedure for the asymmetric synthesis of 4-alkylidenyl glutamic acid derivatives via a catalytic enantioselective tandem conjugate addition-elimination on allylic acetates under chiral phase-transfer conditions is reported. A variety of structural types of allylic acetates have been reacted with the benzophenone imine of glycine tert-butyl ester to give the products in good to excellent yields and enantioselectivities (63-92% yield, 80-97% ee, 8 cases).     

Organocatalytic enantioselective Michael addition of a kojic acid derivative to nitro olefins

By employing a chiral bifunctional thiourea-tertiary amine as catalyst, enantioselective Michael addition of a kojic acid derivative to nitro olefins was realised. The reactions afforded the products with good yields (up to 99%) in good enantioselectivities (up to 97% ee). In addition, the absolute configuration of one product was determined.