Enantioselective Synthesis of Bicyclo[3.2.1]octadienes via Palladium-Catalyzed Intramolecular Alkene-Alkyne Coupling Reaction

Enantioselective Synthesis of Hydrindanes via Palladium-Catalyzed Asymmetric Desymmetrization of Cyclohexadiene Derivatives

We herein disclose a strategy for the asymmetric desymmetrization of cyclohexadiene derivatives via a palladium-catalyzed Heck and tandem Heck/Tsuji-Trost allylic alkoxylation reaction. By employing DCE as the solvent, we obtained a variety of chiral hydrindanes containing an all-carbon quaternary carbon center and a tertiary carbon chiral center in good yields with excellent enantioselectivities. With alcohols as the solvent, the valuable chiral hydrindanes with one quaternary stereocenter and two tertiary centers were constructed with a high level of enantioinduction.

Synthesis of Dioxo-Azabicyclo[3.2.1]octanes via Hypervalent Iodine-Mediated Domino Reaction

Bicyclo[3.2.1]octane (BCO) skeleton widely exists in natural products and biologically active molecules, whereas the development of convenient approaches to construct this structure remains a challenge. Herein, we describe a cascade reaction to synthesize 6,8-dioxa-3-azabicycle[3.2.1]octane derivatives from β-keto allylamines via an oxidation-cyclization reaction. A series of dioxo-azabicyclo[3.2.1]octanes bearing a quaternary carbon center were obtained in good yields under mild reaction conditions. Moreover, the mechanistic rationale for this novel domino reaction is supported by control experiments.

Palladium-Catalyzed Asymmetric Tandem Carbonylation-Heck Reaction of Cyclopentenes to Access Chiral Bicyclo[3.2.1]octenes

A palladium-catalyzed asymmetric tandem carbonylation-Heck reaction of cyclopentenes with carbon monoxide (CO) has been disclosed. This desymmetrization procedure afforded a series of bicyclo[3.2.1]octenes with one chiral quaternary and one tertiary carbon center in good yields with good enantioselectivities. This reaction proceeds via an acyl-palladium intermediate, followed by migratory insertion of the alkenes.

Palladium-Catalyzed Asymmetric Desymmetrization for the Simultaneous Construction of Chiral Phosphorus and Quaternary Carbon Stereocenters

A palladium-catalyzed asymmetric tandem Heck and carbonylation of bisallyl-phosphine oxides has been developed. This desymmetrization process provided an efficient route to the simultaneous synthesis of a chiral P-stereogenic center and a chiral quaternary carbon stereocenter in good yields with good diastereo- and enantioselectivities.

Pd-Catalyzed Enantioselective Desymmetrizing 1,7-Enyne Cycloisomerization of Alkyne-Tethered Cyclopentenes

An enantioselective Pd-catalyzed intramolecular desymmetrizing cycloisomerization of N-(cyclopent-3-en-1-yl)propiolamides has been developed by employing a new chiral phosphoramidite ligand. A series of structurally unique bridged azabicycles are achieved in moderate to excellent yields with good E/Z selectivity and high enantioselectivity. Synthetic transformations are conducted to demonstrate the practical utility of this reaction.

Oxygen-Dependent Ligand-Controlled Iron-Catalyzed Chemoselective Synthesis of Olefins and Vinyl Nitriles

An oxygen-dependent ligand-controlled chemoselective synthesis of vinyl nitriles and E-olefins by coupling a variety of alcohols and benzyl cyanides, catalyzed by a well-characterized, air-stable, easy-to-prepare Fe(II) catalyst (1a) bearing a redox-active arylazo pincer (L1a) is reported. The azo-moiety of the ligand backbone acts as an electron and hydrogen reservoir, enabling catalyst 1a to efficiently produce a broad spectrum of vinyl nitriles and E-olefins in moderate to good yields selectively under an oxygen and argon atmosphere, respectively.