Ya-Hui Wang

Highly Diastereo- and Enantioselective Cu-Catalyzed [3+3] Cycloaddition of Propargyl Esters with Cyclic Enamines toward Chiral Bicyclo[n.3.1] Frameworks

A new Cu-catalyzed asymmetric [3 + 3] cycloaddition of propargyl esters with cyclic enamines is reported. With a combination of Cu(OAc)(2)·H(2)O and a chiral tridentate ferrocenyl-P,N,N ligand as the catalyst, perfect endo selectivities (endo/exo > 98/2) and excellent enantioselectivities (up to 98% ee) for endo cycloadducts were achieved under mild conditions. This method provides a simple and efficient approach for the synthesis of optically active bicyclo[n.3.1] frameworks.

Enantioselective synthesis of highly functionalized dihydrofurans through copper-catalyzed asymmetric formal [3+2] cycloaddition of β-ketoesters with propargylic esters.

An enantioselective synthesis of highly functionalized dihydrofurans through a copper-catalyzed asymmetric [3+2] cycloaddition of β-ketoesters with propargylic esters has been developed. With a combination of Cu(OTf)2 and a chiral tridentate P,N,N ligand as the catalyst, a variety of 2,3-dihydrofurans bearing an exocyclic double bond at the 2u2005position were obtained in good chemical yields and with good to high enantioselectivities. The exocyclic double bond can be hydrogenated in a highly diastereoselective fashion to give unusual cis-2,3-dihydrofuran derivatives, thus further enhancing the scope of this transformation.

Enantioselective copper-catalyzed decarboxylative propargylic alkylation of propargyl β-ketoesters with a chiral ketimine P,N,N-ligand.

The first enantioselective copper-catalyzed decarboxylative propargylic alkylation has been developed. Treatment of propargyl β-ketoesters with a catalyst, prepared in situ from [Cu(CH3 CN)4 BF4 ] and a newly developed chiral tridentate ketimine P,N,N-ligand under mild reaction conditions, generates β-ethynyl ketones in good yields and with high enantioselectivities without requiring the pregeneration of ketone enolates. This new process provides facile access to a range of chiral β-ethynyl ketones in a highly enantioenriched form.

Highly Enantioselective Copper-Catalyzed Propargylic Substitution of Propargylic Acetates with 1,3-Dicarbonyl Compounds

A chiral tridentate ketimine P,N,N-ligand has been successfully applied in the copper-catalyzed enantioselective propargylic substitution of propargylic acetates with a variety of β-dicarbonyl compounds, in which excellent enantioselectivities (up to >99% ee) and high yields have been obtained.

Desilylation-Activated Propargylic Transformation: Enantioselective Copper-Catalyzed [3+2] Cycloaddition of Propargylic Esters with β-Naphthol or Phenol Derivatives.

A copper-catalyzed asymmetric [3+2] cycloaddition of 3-trimethylsilylpropargylic esters with either β-naphthols or electron-rich phenols has been realized and proceeds by a desilylation-activated process. Under the catalysis of Cu(OAc)2⋅H2O in combination with a structurally optimized ketimine P,N,N-ligand, a wide range of optically active 1,2-dihydronaphtho[2,1-b]furans or 2,3-dihydrobenzofurans were obtained in good yields and with high enantioselectivities (up to 96u2009% ee). This represents the first desilylation-activated catalytic asymmetric propargylic transformation.

Enantioselective Copper-Catalyzed Formal [4 + 2] Cycloaddition of o-Aminophenol Derivatives with Propargylic Esters for Synthesis of Optically Active 3,4-Dihydro-2H-1,4-benzoxazines

The first copper-catalyzed asymmetric formal [4 + 2] cycloaddition of o-aminophenol derivatives with propargylic esters as the bis-electrophilic C2 synthons for the stereoselective construction of chiral 2,3,4-trisubstituted 2H-1,4-benzoxazines bearing an exocyclic double bond has been developed. By using a structurally modified chiral ketimine P,N,N-ligand, a wide range of optically active 2H-1,4-benzoxazines were prepared in high yields and with excellent enantioselectivities (up to 97% ee).

Chiral Phosphine-Phosphoramidite Ligands for Highly Efficient Ir-Catalyzed Asymmetric Hydrogenation of Sterically Hindered N-Arylimines

A mild and general iridium-catalyzed, highly enantioselective hydrogenation of sterically hindered N-arylimines with a new H(8)-BINOL-derived phosphine-phosphoramidite ligand has been developed. The present catalytic system features high turnover numbers (up to 100000) and good to perfect enantioselectivities (up to 99% ee) for the hydrogenation of a variety of sterically hindered N-arylimines.