Copper-Catalyzed Enantioconvergent Radical C(sp^(3))−N Cross- Coupling to Access Chiral α-Amino-β-lactams

A copper-catalyzed enantioconvergent radical C-(sp^(3))-N cross-coupling of racemic tertiaryα-bromo-β-lactams with aromatic amines is developed under mild thermal reaction conditions.The use of a sterically demanded oxazoline-derived sulfonamide N,N,N-ligand is crucial for the reaction initiation and effective enantio-discrimination of the azetidinone-derived cyclic alkyl radicals.The strategy provides an attractive approach to access chiralα-amino-β-lactams,an important structural motif in many biologically active molecules.Preliminary mechanistic studies support the formation of azetidinone-derived alkyl radicals from the L*Cu(I)-amido complex andα-bromo-β-lactams.

An improved synthesis of (-)-7-isopropyl-cis-l-amino-2-indanol the chiral auxiliary for 6π-azaelectrocyclization

（-）-7-Isopropyl-cis-l-amino-2-indanol, a key chiral auxiliary and ligand in the highly stereo-selective asymmetric 6π- azaelectrocyclization, has been prepared previously by two methods. Each however involved using of one extreme condition, i.e. high temperature or high pressure, for the respective reaction. A modified reaction route employed mild condition for synthesis was presented in this report.

Synthesis,Characterization and Structure of Chiral Amino Acids and Their Corresponding Amino Alcohols with Camphoric Backbone

Chiral amino acids and their corresponding amino alcohols bearing camphoric backbone were prepared from D-（＋）-camphoric imide and characterized by infrared, elemental analysis, ESI-MS, and NMR measurements. Among them, one intermediate （1S,3R）-3-amino-2,2,3- trimethyl cyclopentane-1-carboxylic acid hydrochloride 3 was structurally elucidated by X-ray diffraction techniques. Versatile intermolecular hydrogen bonding interactions observed in its packing structure result in a two-dimensional framework.

Free amino group-directed C(sp^(2))-H arylation ofα-amino-β-aryl esters by palladium catalysis

Native amino-directed palladium-catalyzed C(sp^(3))-H activation/functionalization has been developed for modification ofα-amino acids and peptides.Herein a palladium(Ⅱ)-catalyzed C(sp^(2))-H arylation ofα-amino-β-aryl esters has been disclosed,using the native amino as the directing group.A variety of chiralα-amino-β-aryl esters can be functionalized to give the corresponding ortho-substituted mono-and di-arylated products.

Asymmetric Synthesis of All Four Isomers of an Unusual Heterocycle-Containing Amino Acid ： 2-Amino-3-furan-2-yl-pentanoic Acid

All four isomers of a novel fl-branched unusual amino acid were designed and synthesized with high stereoselectivity （〉 90% de） and in 33%--44% overall yields by the use of 4（R/S）-5,5-dimethyl-4-phenyl-oxazolidin-2-one as the chiral auxiliary via asymmetric 1,4-Michael addition, direct or indirect azidation, hydrolysis and hydrogenation reactions.

Asymmetric synthesis of binaphthyls through photocatalytic crosscoupling and organocatalytic kinetic resolution

By capitalizing on the capability of photoredox catalysis to generate reactive radical intermediate under mild conditions, we established a photocatalytic cross-coupling protocol that could deliver both derivatives from 1-bromo-2-naphthols in combination with 2-naphthols or 2-naphthylamines. This distinct activation mode could overcome structural or electronic limitation associated with conventional coupling pathways. Additionally, a novel kinetic resolution protocol of unprotected BINOLs has been established with azodicarboxylates via chiral phosphoric acid(CPA) catalysis. Selectivity factor of up to 175 could be achieved and delivered to both enantiomers in atropisomerically enriched form after a simple work-up.