Rhodium-Catalyzed Enantioselective Research Articles

Rhodium-Catalyzed Enantioselective Addition of Heteroarenium Salts Enabled by Nucleophilic Cyclization of 2-Alkynylanilines.

Transition-metal-catalyzed cyclative coupling of 2-alkynylanilines provides a feasible routine for accessing functionalized indoles. Herein, a rhodium-catalyzed highly enantioselective addition of heteroarenium salts is presented, which is enabled by the nucleophilic cyclization of 2-alkynylanilines. It offers feasible protocols to access enantioenriched functionalized indoles tethered to 1,2-dihydropyridine and 1,2-dihydroquinoline motifs with excellent enantioselectivities.

Rhodium-Catalyzed Enantioselective Diarylcarbene Insertion into Si–H Bonds

Rhodium-Catalyzed Enantioselective Diarylcarbene Insertion into Si–H Bonds

Construction of 1-Tetralols Bearing Two Contiguous Quaternary Chiral Centers through a Rhodium-Catalyzed Enantioselective Desymmetrization Cascade Reaction.

A novel and efficient access to polyfunctionnalized chiral 1-tetralols, bearing two contiguous quaternary carbon stereocenters, has been developed from various and easily accessible alkynyl-1,3-diketones, through a cascade process including a regioselective alkyne insertion, a 1,4-Rh shift, and a nucleophilic addition step via the desymmetrization of the 1,3-diketone moiety thanks to an appropriate rhodium-chiral diene complex in the presence of arylboronic acids.

Rhodium-Catalyzed Enantioselective Addition of Arylboroxines to Isatin-Derived N-Boc Ketimines Using Chiral Phosphite-Olefin Ligands: Asymmetric Synthesis of 3-Aryl-3-amino-2-oxindoles.

An efficient rhodium-catalyzed enantioselective arylation of isatin-derived N-Boc ketimines with arylboroxines has been developed using H8-BINOL-derived phosphite-olefin as a chiral ligand. This method allows access to a broad variety of valuable tetrasubstituted 3-amino-2-oxindole derivatives in good yields (up to 98%) with excellent enantioselectivities (up to 98% ee).

Rhodium-Catalyzed Enantioselective Decarboxylative Alkynylation of Allenes with Arylpropiolic Acids.

A rhodium-catalyzed chemo-, regio-, and enantioselective intermolecular decarboxylative alkynylation of terminal allenes with arylpropiolic acids is reported. Employing a Rh(I)/(R)-Tol-BINAP catalytic system, branched allylic 1,4-enynes were obtained under mild conditions. The overall utility of this protocol is exemplified by a broad functional group compatibility.

Rhodium-Catalyzed Enantioselective Conjugate Addition of Electron-Rich Alkenes

Rhodium-Catalyzed Enantioselective Conjugate Addition of Electron-Rich Alkenes

Rhodium-Catalyzed Enantioselective Cascade Cyclopropanation

Key words rhodium - cascade reaction - cyclopropanation - sulfonylhydrazones - carbenes - vinylcyclopropanes

Rhodium-Catalyzed Enantioselective Addition of Tricyclopropylboroxin to N-Sulfonylimines

A hydroxorhodium complex coordinated with a chiral diene ligand efficiently catalyzed the asymmetric addition of tricyclopropylboroxin to <i>N</i>-sulfonylimines in high yields and high enantioselectivities.

Rhodium-Catalyzed Enantioselective Cycloisomerization to Cyclohexenes Bearing Quaternary Carbon Centers.

We report a Rh-catalyzed enantioselective cycloisomerization of α,ω-heptadienes to afford cyclohexenes bearing quaternary carbon centers. Rhodium(I) and a new SDP ligand promote chemoselective formation of a cyclohex-3-enecarbaldehyde motif that is inaccessible by the Diels-Alder cycloaddition. Various α,α-bisallylaldehydes rearrange to generate six-membered rings by a mechanism triggered by aldehyde C-H bond activation. Mechanistic studies suggest a pathway involving regioselective carbometalation and endocyclic β-hydride elimination.

Back Cover: Direct Synthesis of Chiral 3-Arylsuccinimides by Rhodium-Catalyzed Enantioselective Conjugate Addition of Arylboronic Acids to Maleimides (Chem. Eur. J. 31/2015)

Back Cover: Direct Synthesis of Chiral 3-Arylsuccinimides by Rhodium-Catalyzed Enantioselective Conjugate Addition of Arylboronic Acids to Maleimides (Chem. Eur. J. 31/2015)

Rhodium-Catalyzed Enantioselective Addition of Thiols to Allenes

Rhodium-Catalyzed Enantioselective Addition of Thiols to Allenes

ChemInform Abstract: Rhodium‐Catalyzed Enantioselective Addition of Organoaluminum Reagents to N‐Tosyl Ketimines.

AbstractThe first enantioselective 1,2‐addition of methyl‐ and arylaluminum reagents to cycloalkenone‐derived N‐tosyl imines, yielding α‐tertiary allylamides, is developed.

Rhodium-catalyzed enantioselective addition of organoaluminum reagents to N-tosyl ketimines.

Rhodium(I)/Binap complexes catalyze highly enantioselective additions of methyl- and arylaluminum reagents to cyclic α,β-unsaturated N-tosyl ketimines. Depending on the solvent and substituents at the ring, the reaction occurs either in a 1,2-manner to deliver α-tertiary allylic amines or in a 1,4-manner to yield, after subsequent reduction, 3-substituted cycloalkyl amines. Well known in the case of the respective cycloalkenones, these first transformations of the aza-analogues enable the synthesis of amine structures of pharmaceutical and biochemical interest.

ChemInform Abstract: Rhodium‐Catalyzed Enantioselective Hydrogenation of Oxime Acetates.

Rh-catalyzed enantioselective hydrogenation of oxime acetates was first reported, which afforded a new approach for chiral amine synthesis.

Rhodium-Catalyzed Enantioselective Vinylogous Addition of Enol Ethers to Vinyldiazoacetates

A highly asymmetric vinylogous addition of acyclic silyl enol ethers to siloxyvinyldiazoacetate is described. The reaction features a diastereoselective 1,4-siloxy group migration event. Products are obtained in up to 97% ee. When more sterically crowded silyl enol ethers are employed, an enantioselective formal [3+2] cycloaddition becomes the dominant reaction pathway. Control experiments reveal the (Z)-olefin geometry to be critical for high levels of enantiocontrol.

Rhodium-Catalyzed Enantioselective Addition of Boronic Acids to N-Benzylnicotinate Salts

The highly enantioselective catalytic asymmetric addition of aryl and alkenylboronic acids to N-benzylnicotinate salt 1 is described. The dihydropyridine 2 reaction products can be converted to synthetically useful piperidines. Application of the methodology to the preparation of enantioenriched quaternary chiral centers is also discussed.

Rhodium-Catalyzed Enantioselective Multicomponent Reaction

Rhodium-Catalyzed Enantioselective Multicomponent Reaction

Rhodium-Catalyzed Enantioselective Cycloaddition Route to Indolizidines

Described herein is a synthesis of indolizidines by an asymmetric Rh(I)-catalyzed [2+2+2] cycloaddition of 1,1-disubstituted alkenyl isocyanates to terminal alkynes. The reaction proceeds in moderate to high yields with a high level of enantio- and regioselectivity in the presence of the phosphoramidite ligands. Aliphatic alkynes gave lactams A as major products whereas vinylogous amides B predominated with aryl alkynes. The formation of 2-pyridones E as the major byproduct was suppressed under high dilution reaction conditions (typically 0.04 M). The isolated yields were low with sterically demanding substituents (e.g., R1 = i-Pr, Cy) and in such reactions an increase in the 2-pyridone byproduct was observed, presumably due to a slow rate of coordination-insertion of the alkene with Rh.

Design and Preparation of a Chiral Ligand Based on a Pseudorotaxane Skeleton: Application to Rhodium-Catalyzed Enantioselective Hydrogenation of Enamides

We have prepared a novel pseudorotaxane molecule which works as a chiral bidentate ligand having a phosphine moiety in an axle and a phosphite moiety in a wheel as two coordination sites and applied it successfully to the rhodium-catalyzed enantioselective hydrogenation of enamides (up to 96% ee). To the best of our knowledge, this is the first successful example of the use of the pseudorotaxane molecule as a chiral ligand for homogeneous transition-metal-catalyzed asymmetric reactions.

Hydrogen Bonding Makes a Difference in the Rhodium-Catalyzed Enantioselective Hydrogenation Using Monodentate Phosphoramidites

A new generation of monodentate phosphoramidite ligands bearing a primary amine moiety was found to display comparable or better efficiency than bisphosphines in the Rh-catalyzed asymmetric hydrogenation of challenging substrates, such as (Z)-methyl alpha-acetoxyacrylate or (E)-beta-aryl itaconate derivatives, affording the corresponding hydrogenation products with excellent enantioselectivities (up to >99% ee). The presence of intermolecular hydrogen bonding (HB) between two monodentate ligands in the catalyst was found to be critical for excellent catalyst performance. This finding provides a basis for design and development of further catalyst systems using this type of monodentate phosphoramidite ligands.