Highly Enantioslective Synthesis of Multisubstituted Polyfunctional Dihydropyrrole via an Organocatalytic Tandem Michael/Cyclization Sequence

A unique approach to asymmetric synthesis of various optically pure multisubstituted 2,3-dihydropyrroles catalyzed by a novel rosin-derived tertiary amine–thiourea via a tandem Michael/cyclization sequence with high yield (up to 97%) and good to excellent enantioselectivities (up to 97% ee) is present. This strategy provides an efficient and convenient method to access enantioenrich nitrogen heterocycles

Highly Enantioslective Synthesis of Multisubstituted Polyfunctional Dihydropyrrole via an Organocatalytic Tandem Michael/Cyclization Sequence

A unique approach to asymmetric synthesis of various optically pure multisubstituted 2,3-dihydropyrroles catalyzed by a novel rosin-derived tertiary amine–thiourea via a tandem Michael/cyclization sequence with high yield (up to 97%) and good to excellent enantioselectivities (up to 97% ee) is present. This strategy provides an efficient and convenient method to access enantioenrich nitrogen heterocycles

Enantioselective Nucleophilic Addition of Trimethylsilylacetylene to <i>N</i>-Phosphinoylimines Promoted by <i>C</i>₂-Symmetric Proline-Derived β-Amino Alcohol

Both C2- and C3-symmetric proline-derived β-amine alcohol ligands were designed, synthesized, and successfully applied to the enantioselective direct addition of trimethylsilylacetylene to N-phosphinoylimines. Aromatic, heteroaromatic, and aliphatic N-(diphenylphosphinoyl) imines and several N-(diethoxyphosphoryl) imines were tested, and optically active propargylic amides in good yields (up to 92%) and excellent enantioselectivities (up to 95%) were obtained by the simple experimental procedure. The convenience, mild conditions, and easy deprotection of the phosphonamide products made the present method very attractive. Furthermore, the Michael-type addition process of CN alkynylation was studied and proposed on the basis of React 31P NMR investigation

Zinc-Mediated Diastereoselective Synthesis of 3-Amino Oxindoles by Addition of Methyl and Terminal Alkynes to <i>N</i>-<i>tert</i>-Butanesulfinyl Ketimines

A zinc-mediated addition of methyl and terminal alkynes to chiral <i>N</i>-<i>tert</i>-butanesulfinyl ketimines for the preparation of optical quaternary 3-amino oxindoles was reported. In general, the operationally simple reaction affords the desired products in high yields and good to excellent diastereoselectivities. Subsequent convenient cleavage of sulfinyl protecting group under mild conditions was presented without racemization

Highly Enantioselective Addition of Phenylacetylene to Aldehydes Catalyzed by a Camphorsulfonamide Ligand

The asymmetric addition of phenylacetylene to aldehydes was carried out by using a camphorsulfonamide titanium complex as a catalyst. The reactions proceeded under mild conditions and gave the products with good yields and high ees. This system is very useful for the synthesis of chiral propargylic alcohol

Synthesis of <i>N</i>-Alkoxycarbonyl Ketimines Derived from Isatins and Their Application in Enantioselective Synthesis of 3-Aminooxindoles

A simple and general method in the synthesis of N-alkoxycarbonyl ketimines derived from isatins has been described first. Generally, the enantioselective addition of 1,3-dicarbonyl compounds to this kind of ketimine affords chiral 3-amino oxindoles in high yield and excellent ee

Asymmetric Aza-Mannich Addition of Oxazolones to <i>N</i>-Tosyl Aldimines: Synthesis of Chiral α-Disubstituted α,β-Diamino Acids

An organocatalytic enantioselective addition of oxazolones to N-tosyl aldimines has been developed. The process is promoted by a readily prepared cinchona alkaloid ligand and affords a series of valuable α-disubstituted α,β-diamino acid derivatives with excellent enantioselectivities (up to 97% ee) and diastereoselectivities (up to >30:1 dr). The adducts can be transformed into the corresponding protected chiral α-disubstituted α,β-diamino acids by a one-pot hydrolyzed reaction smoothly

Asymmetric Aza-Mannich Addition of Oxazolones to <i>N</i>-Tosyl Aldimines: Synthesis of Chiral α-Disubstituted α,β-Diamino Acids

An organocatalytic enantioselective addition of oxazolones to N-tosyl aldimines has been developed. The process is promoted by a readily prepared cinchona alkaloid ligand and affords a series of valuable α-disubstituted α,β-diamino acid derivatives with excellent enantioselectivities (up to 97% ee) and diastereoselectivities (up to >30:1 dr). The adducts can be transformed into the corresponding protected chiral α-disubstituted α,β-diamino acids by a one-pot hydrolyzed reaction smoothly

Synthesis of <i>N</i>-Alkoxycarbonyl Ketimines Derived from Isatins and Their Application in Enantioselective Synthesis of 3-Aminooxindoles

A simple and general method in the synthesis of <i>N</i>-alkoxycarbonyl ketimines derived from isatins has been described first. Generally, the enantioselective addition of 1,3-dicarbonyl compounds to this kind of ketimine affords chiral 3-amino oxindoles in high yield and excellent ee

Highly Enantioselective Phenylacetylene Additions to Ketones Catalyzed by (<i>S</i>)-BINOL−Ti Complex

The readily available and inexpensive (S)-BINOL ligand in combination with Ti(OiPr)4 is an effective chiral catalyst for the catalytic asymmetric addition of alkynylzinc to unactivated simple ketones. Good to excellent enantioselectivities were achieved. No previous case has been reported successfully using BINOL to catalyze the addition of phenylacetylene to unactivated ketones, and thus the utility of BINOL in asymmetric catalysis is expanded