Highly effective and enantioselective Phospho-Aldol reaction of diphenyl phosphite with N-alkylated isatins catalyzed by quinine

Cinchona alkaloids were first successfully reported to promote enantioselective Phospho-Aldol reaction of diphenyl phosphite to a variety of N-alkylated isatin derivatives in good to excellent yields (up to 99%) and moderate to good enantioselectivities (up to 73% ee) almost in no time.     

Chiral squaramides catalyzed diastereo- and enantioselective Michael addition of α-substituted isocyanoacetates to N-aryl maleimides

An efficient diastereo- and enantioselective Michael addition of α-substituted isocyanoacetates to N-aryl maleimides catalyzed by quinine or cyclohexane-1,2-diamine derived squaramide catalysts has been disclosed, affording the corresponding adducts in good yields (up to 99%), high diastereoselectivities (up to >20:1 dr) and good to excellent enantioselectivities (up to 94% ee) under mild conditions.     

Rhodium catalyzed asymmetric 1,4-addition of arylboronic acids to β,γ-unsaturated α-keto ester using chiral tert-butanesulfinylphosphines ligands

Rh-Catalyzed asymmetric 1,4-selective addition of arylboronic acids to β,γ-unsaturated α-keto ester was developed using chiral tert-butanesulfinylphosphine as ligand, good yields (up to 87%), good 1,4-regioselectivities (up to 96:4), and high enantioselectivities (up to 94% ee) were achieved.     

Probing electronic and regioisomeric control in an asymmetric Henry reaction catalyzed by camphor-imidazoline ligands

Starting from (R)-camphordiamine, 13 new camphor-annulated imidazoline ligands are synthesized in good yields as two regioisomeric series. Yields of up to 94% and good enantioselectivities up to 67% are achieved for the copper(II)-catalyzed Henry reaction giving the product stereoselectively according to the regioisomer used.     

Lewis Base Organocatalyzed Enantioselective Hydrosilylation of α-Keto Ketimines

A chiral Lewis base organocatalyzed enantioselective hydrosilylation ofa-keto ketimines was investigated.The reactions afforded various enantioenriched a-amino ketones with good yields（up to 95％） in moderate to good enantioselectivities（up to 98％ e.e.）.Furthermore,one of the products was reduced to a chiral 1,2-amino alcohol.Following cyclization of it with triphosgene generated a cannabinoid receptor 1 （CB 1） inhibitor with good diastereoselectivity.     

Facile synthesis of chiral 2-amino-4-(indol-3-yl)-4H-chromene derivatives using thiourea as the catalyst

The enantioselective Friedel–Crafts alkylation of indoles with iminochromenes catalyzed by a bifunctional thiourea organocatalyst was investigated. This reaction afforded chiral functionalized 2-amino-4-(indol-3-yl)-4H-chromenes in good yields (up to 87% yield) and with moderate to good enantioselectivities (up to 86% ee).     

Organocatalytic enantioselective tandem Michael addition-oxidation of 3-substituted oxindoles with 1,4-benzoquinone

By employing a chiral bifunctional thiourea-tertiary amine as catalyst, enantioselective tandem Michael addition-oxidation of 3-monosubstituted oxindoles with 1,4-benzoquinones were realized. The reactions afforded a wide range of 3,3-disubstituted oxindoles with moderate to good yields (up to 87%) in moderate to good enantioselectivities (up to 96%).     

Asymmetric synthesis of aziridines by reduction of N-tert-butanesulfinyl alpha-chloro imines

Reduction of (RS)-N-tert-butanesulfinyl alpha-halo imines afforded chiral aziridines in good to excellent yields. Upon reduction of (RS)-N-tert-butanesulfinyl alpha-halo imines with NaBH4 in THF, in the presence of 10 equiv of MeOH, (RS,S)-beta-halo sulfinamides were formed in excellent yield (up to 98%) with very good stereoselectivity (>98:2). Simple treatment of the latter (RS,S)-beta-halo-tert-butanesulfinamides with KOH afforded the corresponding (RS,S)-N-(tert-butylsulfinyl)aziridines in quantitative yields. On the contrary, its epimer, (RS,R)-N-(tert-butylsulfinyl)aziridine was synthesized by switchover of the reducing agent from NaBH4 to LiBHEt3. (RS,R)-N-(tert-Butylsulfinyl)aziridines were synthesized in good yields (up to 85%) and diastereoselectivity (up to 92:8) by reduction of (RS)-N-tert-butanesulfinyl alpha-halo imines with LiBHEt3 in dry THF and subsequent treatment with KOH. All chiral aziridines were obtained as a single diastereomer after recrystallization (overall yield up to 91%) or after flash chromatography.     

Chiral rhodium(II,II) dimers catalyzed enantioselective intramolecular aziridination of sulfonamides and carbamates

The asymmetric intramolecular aziridination of unsaturated sulfonamides and carbamates catalyzed by chiral dirhodium(II,II) complexes were achieved in good yields (up to 95%) and enantioselectivity (up to 76% e.e.).     

Asymmetric Michael addition of α-cyano acetates to (E)-1,4-diaryl-2-buten-1,4-diones

An organocatalyzed asymmetric Michael addition of α-cyano acetates to (E)-1,4-diaryl-2-buten-1,4-diones was realized. The reactions afforded various enantioenriched α,α-disubstituted α-cyano acetates with good yields (up to 99%), moderate to good diastereoselectivities (up to 13.3:1) and moderate to good enantioselectivities (up to 94% ee). Furthermore, one of the products was subjected to Paal–Knorr cyclization to provide an α-furanyl-α,α-disubstituted α-cyano acetate in good yield with moderate enantioselectivity. Thus an indirect asymmetric α-heteroarylation of α-cyano acetates has been well established.     

Diastereo- and enantioselective conjugate addition of 3-substituted oxindoles to enones via bifunctional catalysts

This paper presents a synthetically challenging vicinal quaternary-tertiary C–C forming reaction of 3-substituted oxindoles and chalcones by a simple aryl substituted bifunctional thiourea catalyst. The reactions work with a broad range of chalcones, giving chiral 3,3′-substituted oxindoles type compounds with adjacent quaternary-tertiary stereocenters in high yields (up to 99%), very good dr (up to >98:2) and very good ee (up to 96%).     

Enantioselective Michael reaction of α-alkyl-β-keto esters and enones under multifunctional catalysis

An efficient approach for the enantioselective Michael additions of β-alkyl-β-keto esters to β-substituted α,β-unsaturated ketones has been developed. The Michael products could be obtained in good to excellent yields (75-98%) with excellent diastereoselectivities (up to >99:1 dr) and enantioselectivities (up to 96% ee) and could easily be transformed into a synthetically useful hexahydrophenanthrene structure under mild conditions in good yield.     

A convenient route to enantiopure 3-aryl-2,3-diaminopropanoic acids by diastereoselective Mannich reaction of camphor-based tricyclic iminolactone with imines

A novel and convenient route to the asymmetric synthesis of 2,3-diamino acids via Mannich reaction of iminolactones 1a and 1b with N-protected imines has been achieved in good yields (up to 95%) and high diastereoselectivity (dr: >99:1). Hydrolysis of the Mannich adducts under acidic conditions furnished the desired 3-aryl-2,3-diaminopropanoic acids in good yields (up to 85%) with excellent enantiomeric excesses (99% ee).     

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.     

Enantioselective organocatalytic three-component Petasis reaction among salicylaldehydes, amines, and organoboronic acids

The catalytic enantioselective three-component Petasis reaction among salicylaldehydes, amines, and organoboronic acids with a newly designed thiourea-binol catalyst is presented. A broad range of alkylaminophenols can be obtained in good yield (up to 92%) and good to high enantioselectivity (up to 95% ee). A possible reaction pathway for this catalytic enantioselective Petasis reaction is tentatively proposed.     

Organocatalytic asymmetric cascade Michael/hemiketalization/retro-aldol reaction of 3-acetyl-oxindole with β,γ-unsaturated ketoesters catalyzed by bifunctional amino-squaramides

An unprecedented organocatalytic asymmetric Michael/Hemiketalization/retro-aldol cascade sequence catalyzed by bifunctional amino-squaramides is described. The corresponding adducts were generally obtained in high yields (up to 97%) with moderate diastereo- (up to 79:21 dr) and good enantioselectivities (up to 90% ee).     

Proline-based Amino Pyridine Dipeptides as Efficient Organocatalysts for Direct Aldol Reaction

A series of proline-based amino pyridine dipeptide organocatalysts was synthesized and applied in direct asymmetric intermolecular aldol reaction. These catalysts showed good solubility in organic solvents, good yields (73%―97%) and enantioselectivitives(74%―94%). Among them, dipeptide organocatalyst(2) was found to be the most efficient one for the asymmetric aldol reaction between cyclohexanone and 4-nitrobeznaldehyde. After optimizing the catalytic reaction conditions, we found that the catalyst showed high yield(97%), enantioselectivity(e.e., up to 92%) and anti-diastereoselectivity(up to 95:5) at mild room temperature without any additives.     

Enantioselective anti-Mannich reaction catalyzed by modularly designed organocatalysts

A highly stereoselective method for achieving the anti-Mannich reaction of aldehydes and ketones with ethyl (4-methoxyphenylimino)acetate was realized using the modularly designed organocatalysts (MDOs) self-assembled from cinchona alkaloid derivatives and (R)-pyrrolidien-3-carboxylic acid in the reaction media. The desired anti-Mannich products were obtained in good to excellent yields (up to 93%), excellent diastereoselectivities (up to 99:1 dr), and good to high enantioselectivities (up to 99% ee).     

Enantioselective intramolecular Rauhut-Currier reaction catalyzed by chiral phosphinothiourea

Chiral organophosphine-catalyzed enantioselective Rauhut-Currier reaction has been disclosed for the first time. With L-valine-derived phosphinothiourea, the intramolecular Rauhut-Currier reaction of bis(enones) was achieved in good yields (up to 99%) with excellent enantioselectivities (up to 99.4% ee).     

syn-selective direct catalytic asymmetric Mannich-type reactions of hydroxyketones using Y{N(SiMe3)2}3/linked-BINOL complexes

[reaction, structure: see text] Chiral Y{N(SiMe3)2}3/linked-BINOL catalyst generated Y-enolate in situ from various hydroxyketones (R2 = aryl, heteroaryl). Beta-amino-alpha-hydroxy ketones (R1 = aryl, heteroaryl, alkenyl) were obtained syn-selectively (up to 96/4) in high ee (up to 98%) and good yield (up to 98% yield).