Sulfoxide-Mediated α-Arylation of Carbonyl Compounds

A novel sulfoxide-mediated α-arylation of carbonyl compounds is reported. This reaction proceeds under very mild conditions at room temperature and does not require any transition-metal promoter or catalyst

Gold-Catalyzed Oxidative Cascade Cyclization of 1,3-Diynamides: Polycyclic N‑Heterocycle Synthesis via Construction of a Furopyridinyl Core

A facile and practical approach to construct a furopyridinyl motif through a gold-catalyzed cascade cyclization of easily accessible diynamides is described. This strategy offers a straightforward approach to furo­[2,3-c]­isoquinoline and 6H-furo­[3′,2′:5,6]­pyrido­[3,4-b]­indole derivatives. The reaction could build up four new bonds and two additional heteroaromatic rings via a single operation. The heterocyclic products show promising blue luminous performance with fluorescence quantum yields up to 75%

Amination of Diazocarbonyl Compounds: N–H Insertion under Metal-Free Conditions

Transition-metal-free intermolecular N–H insertion of α-diazocarbonyl compounds is reported. Among the series of nitrogen sources examined, dibenzenesulfonimide was found to be the choice in terms of the yields and the reaction time. Primary mechanistic experiments suggest that a pathway involving a sequence of protonation and nucleophilic substitution was preferred

Gold-Catalyzed Intermolecular Nitrene Transfer from 2<i>H</i>‑Azirines to Ynamides: A Direct Approach to Polysubstituted Pyrroles

An effective gold-catalyzed intermolecular nitrene transfer by the reaction of 2<i>H</i>-azirines and ynamides is reported, which provides highly substituted pyrroles in a straightforward manner. This transformation proceeds under mild conditions and gives the polysubstituted pyrroles in good-to-excellent yields. Preliminary results indicate that a nongold carbenoid pathway is preferred for current pyrrole synthesis

Polysubstituted 2‑Aminopyrrole Synthesis via Gold-Catalyzed Intermolecular Nitrene Transfer from Vinyl Azide to Ynamide: Reaction Scope and Mechanistic Insights

A gold-catalyzed intermolecular reaction of vinyl azides and ynamides is described. This process presents an efficient and mild approach to multisubstituted 2-aminopyrroles in good-to-excellent yields. Control experiments were carried out to distinguish the reactivity between vinyl azides and the corresponding 2<i>H</i>-azirines. A plausible reaction mechanism was also proposed according to previous reports and our preliminary mechanistic studies

Sulfur(IV)-Mediated Transformations: From Ylide Transfer to Metal-Free Arylation of Carbonyl Compounds

The development of a direct ylide transfer to carbonyl derivatives and of a sulfoxide-mediated arylation is presented from a unified perspective. Mechanistic studies (including density functional calculations) support a common reaction pathway and showcase how subtle changes in reactant properties can lead to disparate and seemingly unrelated reaction outcomes

Palladium-Catalyzed Three-Component Selective Aminoallylation of Diazo Compounds

We describe a Xantphos-containing dinuclear palladium complex-enabled geminal aminoallylation of diazocarbonyl compounds, which selectively provides a range of quaternary α-amino esters. Direct N–H insertion, allylic alkylation of amino nucleophiles, and diene formation were not observed under standard conditions. Mechanistic studies indicated that a relayed pathway via allylation of the N–H insertion product or [2,3]-sigmatropic rearrangement of an ylide intermediate was unlikely

Divergent Access to Polycyclic <i>N</i>‑Heterocyclic Compounds through Büchner-Type Dearomatization Enabled Cycloisomerization of Diynamides under Gold Catalysis

Catalytic dearomatization has been considered as a valuable approach to convert readily accessible flat molecules to products with three-dimensional frameworks. Herein, an unprecedented gold-catalyzed oxidative Büchner-type cyclopropanation is described that enables the cycloisomerization of diynamides. By variation of the position of substituents on the phenyl ring, a variety of fused N-heterocyclic products with challenging structural skeletons were obtained divergently

Polysubstituted 2‑Aminopyrrole Synthesis via Gold-Catalyzed Intermolecular Nitrene Transfer from Vinyl Azide to Ynamide: Reaction Scope and Mechanistic Insights

A gold-catalyzed intermolecular reaction of vinyl azides and ynamides is described. This process presents an efficient and mild approach to multisubstituted 2-aminopyrroles in good-to-excellent yields. Control experiments were carried out to distinguish the reactivity between vinyl azides and the corresponding 2<i>H</i>-azirines. A plausible reaction mechanism was also proposed according to previous reports and our preliminary mechanistic studies

Understanding the Chemoselectivity in Palladium-Catalyzed Three-Component Reaction of <i>o</i>‑Bromobenzaldehyde, <i>N</i>‑Tosylhydrazone, and Methanol

To understand the ligand-controlled palladium-catalyzed coupling of o-bromobenzaldehyde, N-tosylhydrazone, and methanol to give methyl 2-benzylbenzoic ester or methyl ether, we herein investigated the mechanisms which account for how C–C and C–O bonds are formed and why bidentate dppf/dppb ligands afford ester, whereas P­(o-tolyl)3 ligand gives ether. The ester chemoselectivity of the bidentate ligands is attributed to the strong electron-donating effect that disfavors the C,Br-reductive elimination of the coupling intermediate of o-bromobenzaldehyde and N-tosylhydrazone