Metal-Mediated Synthesis of Medium-Sized Rings

In this review, we summarize the origin and advancements of iridium-catalyzed asymmetric allylic substitution reactions during the past two decades. Since the first report in 1997, Ir-catalyzed asymmetric allylic substitution reactions have attracted intense attention due to their exceptionally high regio- and enantioselectivities. Ir-catalyzed asymmetric allylic substitution reactions have been significantly developed in recent years in many respects, including ligand development, mechanistic understanding, substrate scope, and application in the synthesis of complex functional molecules. In this review, an explicit outline of ligands, mechanism, scope of nucleophiles, and applications is presented.

Iridium-Catalyzed Asymmetric Allylic Substitution Reactions

Recently, our group unveiled a system in which an unusual interplay between copper(I) and Selectfluor effects mild, catalytic sp3 C–H fluorination. Herein, we report a detailed reaction mechanism based on exhaustive EPR, 19F NMR, UV–vis, electrochemical, kinetic, synthetic, and computational studies that, to our surprise, was revealed to be a radical chain mechanism in which copper acts as an initiator. Furthermore, we offer an explanation for the notable but curious preference for monofluorination by ascribing an ionic character to the transition state.

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Direct, Catalytic Monofluorination of sp3 C–H Bonds: A Radical-Based Mechanism with Ionic Selectivity

An asymmetric Ni-catalyzed reductive cross-coupling has been developed to prepare enantioenriched allylic silanes. This enantioselective reductive alkenylation proceeds under mild conditions and exhibits good functional group tolerance. The chiral allylic silanes prepared here undergo a variety of stereospecific transformations, including intramolecular Hosomi-Sakurai reactions, to set vicinal stereogenic centers with excellent transfer of chirality.

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Synthesis of Enantioenriched Allylic Silanes via Nickel-Catalyzed Reductive Cross-Coupling

Ligand and solvent effects on cobalt(I)-catalysed reactions: Alkyne dimerisation versus [2+2+2]-cyclotrimerisation versus Diels–Alder reaction versus [4+2+2]-cycloaddition

Vinylogous aldol products from chiral crotylsilanes obtained by enantioselective Rh(II) and Cu(I) carbenoid Si-H insertion.

Metal-catalyzed 4 + 2 + 2 cycloadditions : cycloadducts of substituted norbornadienes and their opening with zeise's dimer

Stereochemical and skeletal diversity employing pipecolate ester scaffolds.

Opening norbornadiene homo Diels-Alder adducts to bicyclic systems

Deltacyclenes and deltacyclanes produced from the [2+2+2] homo Diels-Alder reaction of norbornadiene are opened to the corresponding biquinanes. Similarly, opening the [4+2+2]-adducts yields the bicyclo[5.3.0]decanes.

Yu Chen

Papers

Vinylogous aldol products from chiral crotylsilanes obtained by enantioselective Rh(II) and Cu(I) carbenoid Si-H insertion.

Metal-catalyzed 4 + 2 + 2 cycloadditions : cycloadducts of substituted norbornadienes and their opening with zeise's dimer

Stereochemical and skeletal diversity employing pipecolate ester scaffolds.

Opening norbornadiene homo Diels-Alder adducts to bicyclic systems

Opening Norbornadiene Homo Diels‐Alder Adducts to Bicyclic Systems.