Chen-Guo Feng

Pd(II)-Catalyzed Phosphorylation of Aryl C–H Bonds

A Pd(II)-catalyzed C-H phosphorylation reaction has been developed using heterocycle-directed ortho-palladation. Both H-phosphonates and diaryl phosphine oxides are suitable coupling partners for this reaction.

Ligand-enabled γ-C-H olefination and carbonylation: construction of β-quaternary carbon centers.

Monoselective γ-C–H olefination and carbonylation of aliphatic acids has been accomplished by using a combination of a quinoline-based ligand and a weakly coordinating amide directing group. The reaction provides a new route for constructing richly functionalized all-carbon quaternary carbon centers at the β-position of aliphatic acids.

Highly enantioselective arylation of N-tosylalkylaldimines catalyzed by rhodium-diene complexes.

A highly enantioselective rhodium-catalyzed arylation of aliphatic N-tosylaldimines has been developed. The combination of chiral bicyclo[3.3.0]octadiene ligands, an active rhodium hydroxide complex, and neutral reaction conditions is the key to achieving high yield and enantioselectivity. The application of this method is demonstrated by the enantioselective synthesis of chiral 2-aryl pyrrolidines and piperidines in a one-pot procedure. Furthermore, excellent results are also obtained for the imine substrates with the more readily cleavable N-nosyl protecting group.

Highly Practical Catalytic Asymmetric 1,4-Addition of Arylboronic Acids in Water Using New Hydrophilic Chiral Bicyclo[3.3.0] Diene Ligands

The first Rh-diene-catalyzed aqueous asymmetric 1,4-addition of alpha,beta-unsaturated carbonyl compounds with arylboronic acids has been realized. By using a hydrophilic bicyclo[3.3.0] diene ligand, the reactions can be performed successfully in neat water at room temperature to afford the corresponding products in good yields and with very high enantioselectivities for both cyclic and linear substrates.

Asymmetric Synthesis of β-Substituted γ-Lactams via Rhodium/Diene-Catalyzed 1,4-Additions: Application to the Synthesis of (R)-Baclofen and (R)-Rolipram

An efficient rhodium/diene-catalyzed asymmetric addition of arylboronic acids to α,β-unsaturated γ-lactams has been developed. The power of this methodology is further demonstrated by the concise synthesis of (R)-baclofen and (R)-rolipram.

C1-symmetric dicyclopentadienes as new chiral diene ligands for asymmetric rhodium-catalyzed arylation of N-tosylarylimines.

Monosubstituted C(1)-symmetric dicyclopentadienes as a new class of diene ligands have been developed for asymmetric arylation of N-tosylarylimines in excellent yields (98-99%) with high enantioselectivities (90-96%). The preparation of these diene ligands relied on an efficient lipase-catalyzed resolution as the key step.

Pd(II)-Catalyzed Ortho-Trifluoromethylation of Benzylamines

The Pd(II)-catalyzed ortho-C-H trifluoromethylation of benzylamines has been achieved utilizing an electrophilic CF3 reagent. Additives, such as H2O and Ag2O, were found to be crucial for obtaining good yields. This protocol will be useful in medicinal chemistry for the preparation of ortho-trifluoromethyl-substituted benzylamines.

Enantioselective Rhodium-Catalyzed Arylation of Cyclic N-Sulfamidate Alkylketimines: A New Access to Chiral β-Alkyl-β-aryl Amino Alcohols

The enantioselective rhodium-catalyzed 1,2-addition of arylboronates to cyclic N-sulfamidate alkylketimines was developed. With a rhodium/diene complex as catalyst, high enantioselectivity and broad functional group tolerance were observed. The resulting sulfamidates can easily be converted into chiral β-alkyl-β-aryl amino alcohols.

Borylation of Olefin C-H Bond via Aryl to Vinyl Palladium 1,4-Migration

The aryl to vinyl palladium 1,4-migration was realized for the first time. The generated alkenyl palladium species was trapped by diboron reagents under Miyaura borylation conditions, providing a new method to synthesize β,β-disubstituted vinylboronates. The excellent regioselectivity and broad substrate scope were observed for this novel transformation.

Enantioselective Alkenylation of Aldimines Catalyzed by a Rhodium–Diene Complex

An efficient rhodium-catalyzed asymmetric addition reaction of potassium alkenyltrifluoroborates to N-nosylaldimines has been developed. Under optimal conditions, the reactions proceeded with good to excellent yields and excellent enantioselectivities (97 → 99% ee). The utility of this method is demonstrated by the formal synthesis of (-)-aurantioclavine.