Renhua Fan

Transition-Metal-Free Intermolecular Amination of sp3 C−H Bonds with Sulfonamides

An efficient transition-metal-free intermolecular benzylic amidation with sulfonamides is described. Various valuable nitrogen-containing compounds, including amines, beta-chloro amine, amino alcohol, alpha-, beta-amino ester, and N-sulfonyl imine, are generated from the preferential N-functionalization of saturated benzylic C-H bonds. The potential of this reaction system also lies in the fact it can be developed into an environmentally friendly intermolecular amidation process.

Solvent-Controlled Oxidative Cyclization for Divergent Synthesis of Highly Functionalized Oxetanes and Cyclopropanes

An efficient solvent-controlled oxidative cyclization of Michael adducts of malonates with chalcones with the combination of iodosobenzene and tetrabutylammonium iodide is reported. Highly functionalized oxetanes and cyclopropanes were divergently synthesized in moderate to excellent yields with high diastereoselectivity.

Construction of 3-oxyindoles via hypervalent iodine mediated tandem cyclization–acetoxylation of o-acyl anilines

An efficient tandem cyclization-acetoxylation of o-acyl anilines mediated by the combination of iodobenzene diacetate with tetrabutylammonium iodide provides a new convenient and useful route to 2-acetoxy indolin-3-ones, which are ready to be converted into other 2-substituted 3-oxyindole derivatives.

Aqueous Iodine(III)-Mediated Stereoselective Oxidative Cyclization for the Synthesis of Functionalized Fused Dihydrofuran Derivatives

An efficient aqueous oxidative cyclization mediated by the combination of iodosobenzene with tetra-(n-butyl)ammonium iodide provides a new convenient and useful route to functionalized fused dihydrofuran derivatives in moderate to excellent yields with high diastereoselectivities.

Dearomatization strategy and palladium-catalyzed domino reaction: construction of azepino[5,4,3-cd]indoles from 2-alkynylanilines.

A facile approach to construct 3,4-fused tricyclic azepino[5,4,3-cd]indoles from 2-alkynyl anilines, isocyanides, and α,β-unsaturated acids is reported. This synthetic process involves a regioselective meta-functionalization of 2-alkynylanilines using a dearomatization strategy and a palladium(II)-catalyzed domino heterocyclization/Heck reaction.

Stereoselective construction of highly functionalized azetidines via a [2 + 2]-cycloaddition.

A facile stereoselective synthesis of highly functionalized azetidines from a novel [2 + 2]-cycloaddition of 2-aminomalonates to chalcones is reported. The desired four-membered ring construction proceeded via a grind-promoted solvent-free Michael addition and a PhIO/Bu(4)NI mediated oxidative cyclization and afforded azetidines in moderate to good yields with excellent diastereoselectivities.

Divergent Construction of Nitrogen-Containing Polycyclic Compounds with a Dearomatization Strategy

The oxidative dearomatization of para-substituted o-alkynylanilines afforded 2-alkynyl cyclohexadienimines, which can act as active substrates for reaction with electron-rich styrenes. The reaction is metal-controlled. Bi(OTf)3-catalyzed reactions afforded 3,4-dihydro-cyclopenta[c,d]indoles, and AgOTf-catalyzed reactions provided tricyclic pyrrole derivatives.

Iodine(III)-Mediated Tandem Acetoxylation−Cyclization of o-Acyl Phenols for the Facile Construction of α-Acetoxy Benzofuranones

An efficient tandem acetoxylation-cyclization of o-acylphenols mediated by the combination of iodobenzene diacetate with tetrabutylammonium iodide provides a new convenient and useful route to alpha-acetoxy benzofuranones.

Direct Assembly of 3,4‐Difunctionalized Benzofurans and Polycyclic Benzofurans by Phenol Dearomatization and Palladium‐Catalyzed Domino Reaction

A method to directly convert 2-alkynylphenols to 3,4-difunctionalized benzofurans and polycyclic benzofurans was developed. This protocol involves a hypervalent-iodine-mediated oxidative dearomatization to break the aromaticity of 2-alkynylphenols, and a palladium-catalyzed domino reaction to install two functional groups at the C3 and the C4 positions and restore the aromaticity of benzofurans.

Oxidative Nucleophilic Cyclization of 2-Alkynylanilines with Thiophenols under Metal-Free Conditions

An oxidative nucleophilic cyclization of 2-alkynylanilines with thiophenols under metal-free conditions was developed. The one-pot two-step reaction involves a PhI(OAc)2-mediated oxidative dearomatization and a Brønsted acid promoted nucleophilic cyclization. DFT calculations were performed to understand the reaction pathway.