Bifunctional AgOAc-Catalyzed Asymmetric [3 + 2] Cycloaddition of Azomethine Ylides

A bifunctional AgOAc-catalyzed asymmetric cycloaddition of azomethine ylides with electronic-deficient alkenes was developed using ferrocenyloxazoline-derived N,P ligands. The reactive metal-bound azomethine ylide dipole is formed by the deprotonation with acetate, and extra base is not necessary. The reactions proceed with high enantioselectivity. This method provides an efficient and convenient route to optically active pyrrolidine derivatives

Synthesis of Tunable Bisphosphine Ligands and Their Application in Asymmetric Hydrogenation of Quinolines

A series of tunable axial chiral bisphosphine ligands have been synthesized from (S)-MeO-Biphep. The Ir complex of the MeO-PEG-supported ligand (S)-4k has been successfully applied in asymmetric hydrogenation of quinolines with up to 92% ee. The catalyst system is air-stable and recyclable

Highly Enantioselective Reductive Amination of Simple Aryl Ketones Catalyzed by Ir−f-Binaphane in the Presence of Titanium(IV) Isopropoxide and Iodine

Using an Ir−f-Binaphane complex as the catalyst, complete conversions and high enantioselectivies (up to 96% ee) were achieved in the asymmetric reductive amination of aryl ketones in the presence of Ti(OiPr)4 and I2. A simple and efficient method of synthesizing chiral primary amines has been realized

Synthesis and Highly Enantioselective Hydrogenation of Exocyclic Enamides: (<i>Z</i>)-3-Arylidene-4-acetyl-3,4-dihydro-2<i>H</i>- 1,4-benzoxazines

Highly enantioselective hydrogenation of exocyclic enamides, (Z)-3-arylidene-4-acyl-3,4-dihydro-2H-benzoxazines, was achieved in up to 98.6% ee by using Rh/(R,R)-Me-Duphos complex as the catalytic system. The absolute configuration of the product was assigned as R by chemical interrelations

Highly Enantioselective Pd-Catalyzed Asymmetric Hydrogenation of Activated Imines

Pd/bisphosphines complexes are highly effective catalysts for asymmetric hydrogenation of activated imines in trifluoroethanol. The asymmetric hydrogenation of N-diphenylphosphinyl ketimines 3 with Pd(CF3CO2)/(S)-SegPhos indicated 87−99% ee, and N-tosylimines 5 could gave 88−97% ee with Pd(CF3CO2)/(S)-SynPhos as a catalyst. Cyclic N-sulfonylimines 7 and 11 were hydrogenated to afford the useful chiral sultam derivatives in 79−93% ee, which are important organic synthetic intermediates and structural units of agricultural and pharmaceutical agents

Palladium-Catalyzed Asymmetric Hydrogenation of Functionalized Ketones

A novel catalytic system for asymmetric hydrogenation of functionalized ketones has been developed using a Pd/bisphosphine complex as the catalyst in 2,2,2-trifluoroethanol. The reaction exhibits high enantioselectivity, and up to 92.2% ee was obtained

Synthesis and Highly Enantioselective Hydrogenation of Exocyclic Enamides: (<i>Z</i>)-3-Arylidene-4-acetyl-3,4-dihydro-2<i>H</i>- 1,4-benzoxazines

Highly enantioselective hydrogenation of exocyclic enamides, (Z)-3-arylidene-4-acyl-3,4-dihydro-2H-benzoxazines, was achieved in up to 98.6% ee by using Rh/(R,R)-Me-Duphos complex as the catalytic system. The absolute configuration of the product was assigned as R by chemical interrelations

Highly Enantioselective Synthesis of Sultams via Pd-Catalyzed Hydrogenation

Using pd(cf3co2)2/(S,S)-f-Binaphane as the catalyst, an efficient enantioselective synthesis of sultams was developed via asymmetric hydrogenation of the corresponding cyclic imines with high enantioselectivities. The hydrogenation products can be conveniently transformed to chiral homoallylic amines without loss of enantioselectivity

Biomimetic Asymmetric Reduction of Tetrasubstituted Olefin 2,3-Disubstituted Inden-1-ones with Chiral and Regenerable NAD(P)H Model CYNAM

Because of the formidable development of the asymmetric reduction of tetrasubstituted olefins, an effective method is in urgent demand. Herein, through the biomimetic protocol of the coenzyme NAD­(P)­H, the reduction of tetrasubstituted olefin 2,3-substituted 1H-inden-1-ones has been successfully realized with the catalytic chiral NAD­(P)H model CYNAM, which is hard to bring about via the common rhodium or iridium-based catalytic system, producing the corresponding products in good yield (up to 98%) with good enantioselectivity (up to 99% ee). Furthermore, the chiral bioactive molecule can be concisely synthesized from the reduced product

Hydrogen-Bonding Directed Reversal of Enantioselectivity

A successful stereochemical reversal was achieved in AgOAc catalyzed [3+2] cycloaddition by the formation of hydrogen bonding between ligand and reactant. This strategy provides an efficient and convenient route to prepare both enantiomers of a chiral compound. DFT studies proposed a reasonable mechanism of the reversal of the enantioselectivity; hydrogen bonding changed the transition state. The strategy may provide some useful hints for ligand design