Highly Site-Selective Direct C–H Bond Functionalization of Phenols with α-Aryl-α-diazoacetates and Diazooxindoles via Gold Catalysis

Modular Synthesis of Tetrasubstituted Vinyl Sulfides via One-Pot Sequential Carbene Transfer Reaction from Thiols with α-Diazo Carbonyl Compounds

We present a one-pot reaction that offers an efficient approach to synthesizing tetrasubstituted vinyl sulfides with high stereoselectivity. This method involves the sequential Wolff rearrangement, ylide formation, and [1,4]-aryl transfer by utilizing aryl and alkyl thiols and α-diazo carbonyl compounds as substrates. Notably, this reaction features commercially available materials, straightforward operation, atom economy, and broad substrate scope. Moreover, the primary photophysical properties (aggregation-induced emission effect) of the products were also investigated, which might be useful in functional materials via structural modification.

Enantioselective de novo construction of 3‑oxindoles via organocatalyzed formal [3 + 2] annulation from simple arylamines

The de novo construction of enantioenriched 3-hydroxyindolenines and 3-oxindoles from easily available starting materials has been highly desired. Herein, an enantioselectively intermolecular direct [3 + 2] annulation of aryl amine with 2,3-diketoesters to construct 3-hydroxyindolenines with a chiral tertiary alcohol has been disclosed. The results of control experiments and DFT calculation revealed that π - π interaction plays a pivotal role in the enantioselectivity-determining process of [3 + 2] annulation. The following unusual concerted [1,2]-ester migration provides a family of chiral 3-oxindoles in good to excellent yields with excellent enantioselectivity.

Heterogeneous Rhodium Single-Atom-Site Catalyst Enables Chemoselective Carbene N-H Bond Insertion

Transition-metal-catalyzed carbene insertion reactions of a nitrogen-hydrogen bond have emerged as robust and versatile methods for the construction of C-N bonds. While significant progress of homogeneous catalytic metal carbene N-H insertions has been achieved, the control of chemoselectivity in the field remains challenging due to the high electrophilicity of the metal carbene intermediates. Herein, we present an efficient strategy for the synthesis of a rhodium single-atom-site catalyst (Rh-SA) that incorporates a Rh atom surrounded by three nitrogen atoms and one phosphorus atom doped in a carbon support. This Rh-SA catalyst, with a catalyst loading of only 0.15 mol %, exhibited exceptional catalytic performance for heterogeneous carbene insertion with various anilines and heteroaryl amines in combination with diazo esters. Importantly, the heterogeneous catalyst selectively transformed aniline derivatives bearing multiple nucleophilic moieties into single N-H insertion isomers, while the popular homogeneous Rh2(OAc)4 catalyst produced a mixture of overfunctionalized side products. Additionally, similar selectivities for N-H bond insertion with a set of stereoelectronically diverse diazo esters were obtained, highlighting the general applicability of this heterogeneous catalysis approach. On the basis of density functional theory calculations, the observed selectivity of the Rh-SA catalyst was attributed to the insertion barriers and the accelerated proton transfer assisted by the phosphorus atom in the support. Overall, this investigation of heterogeneous metal-catalyzed carbene insertion underscores the potential of single-atom-site catalysis as a powerful and complementary tool in organic synthesis.

Environmentally Friendly Synthesis of Highly Substituted Phenols Using Enallenoates and Grignard Reagents

We developed an efficient and environmentally friendly methodology for selectively synthesizing highly substituted phenols using readily available enallenoates and Grignard reagents. This method consistently yields good to excellent results across over 60 examples, demonstrating the substrate scope and the exploration of phenol product derivatization, further extending the method's utility.

Doyle-Kirmse Reaction on Alkynyl Hydrazone Carboxylates: Synthesis of 1,4-Allenyne and 1,5-Enyne Thioaryl Carboxylates

The first Doyle-Kirmse reaction on alkynyl diazoacetates using allyl/propargyl sulfides is reported. The development provides diversified 1,5-enyne and 1,4-allenyne thioaryl carboxylates in good yields under ligand-/additive-free AuCl and Rh2(OAc)4 catalysis, respectively (48 examples, up to 96% yield). The study demonstrated the dual role of allyl sulfide as a ligand and substrate. Also, we have exemplified various synthetic modifications of the products to showcase the utility of different functional groups.

Facile Friedel-Crafts alkylation of arenes under solvent-free conditions

The Friedel-Crafts alkylation of arenes is an important part of electrophilic aromatic substitution reactions. However, the reactivity of arenes is weakened by electron-withdrawing substituents, leading to limited substrate scopes and applications. Herein, we developed an efficient HOTf-promoted Friedel-Crafts alkylation reaction of broad arenes with α-aryl-α-diazoesters under metal-free and solvent-free conditions.

Csp2-H functionalization of phenols: an effective access route to valuable materials via Csp2-C bond formation

In the vast majority of top-selling pharmaceutical and industrial products, phenolic structural motifs are highly prevalent. Non-functionalized simple phenols serve as building blocks in the synthesis of value-added chemicals. It is worth mentioning that lignin, being the largest renewable biomass source of aromatic building blocks in nature, mainly consists of phenolic units, which enable the production of structurally diverse phenols. Given their remarkable applicability in the chemical value chain, many efforts have been devoted to increasing the molecular complexity of the phenolic scaffold. Among the key techniques, direct functionalization of Csp2-H is a powerful tool, enabling the construction of new Csp2-C bonds in an economical and atomic manner. Herein we present and summarize the large plethora of direct Csp2-H functionalization methods that enables scaffold diversification of simple, unprotected phenols, leading to the formation of new Csp2-C bonds. In this review article, we intend to summarize the contributions that appeared in the literature mainly in the last 5 years dealing with the functionalization of unprotected phenols, both catalytic and non-catalytic. Our goal is to highlight the key findings and the ongoing challenges in the stimulating and growing research dedicated to the development of new protocols for the valorization of phenols.

Rhodium-Catalyzed C(sp2)-O Cross Couplings of Diazo Quinones with Phenols to Construct Diaryl Ethers

The diaryl ether represents a prevalent structural motif found in numerous biologically active molecules. Herein, we describe a dirhodium-catalyzed C(sp2)-O cross coupling reaction between diazo quinones and phenols for the construction of diaryl ethers in moderate to high yields. The reaction proceeds under mild and neutral conditions and is tolerant of various functional groups. The synthetic method has been successfully applied to the concise synthesis of a Navl.7 inhibitor.

B(C6 F5 )3 -Catalyzed [2+3]-Cyclative o,m-diC-H Functionalization of Phenols

Metal-free catalytic C-H functionalization is highly desired for the construction of C-C bonds. We herein report a highly chemoselective consecutive C-H [2+3]-cyclative functionalization for the simultaneous formation of two C-C bonds with construction of polycyclic phenols catalyzed by commercially available and low-cost B(C6 F5 )3 . This catalytic system tolerates a wide range of substrate scope, providing a series of 2,6,7,8-tetrahydroacenaphthylen-3-ol-type polycyclic compounds efficiently. Several derivatizations of the catalytic products have also been conducted to show the potential application of this method in synthesis of polycyclic compounds.

Umpolung Reactivity of Diazo Arylidene Succinimides: Distal C-H Functionalization of α-Thiocarbonyls from the Reactive Carbenoid Center

Herein, for the first time we have explored the umpolung reactivity of the vinylogous carbon center of diazo arylidene succinimide (DAS) through rhodium catalysis to achieve [2,3]-Stevens rearrangement of α-thioether esters. The protocol has successfully demonstrated the distal C-H bond functionalization of the α-thioether esters. Alongside, the carbenoid reactivity of DAS has also been achieved with Doyle-Kirmse reaction of allyl/propargyl phenyl sulfides. The protocol proved to be practical to synthesize a wide variety of [2,3]-Stevens rearrangement products exclusively and the possible side products emanating from Pummerer rearrangement and [1,2]-Stevens rearrangement were not observed. This catalytic protocol works smoothly in environmentally benign solvent under open air to afford the corresponding desired products with excellent diastereo-, regio- and chemo-selectivities in good to excellent yields. The protocol also proved to be scalable on gram quantity.

Borane catalyzed transesterification of tert-butyl esters using α-aryl α-diazoesters

The B(C6F5)3-catalyzed transesterification of a series of 3-alkenyl-oxindoles and other unsaturated tert-butyl esters with aryl-diazo esters is reported. This protocol is facile and generally high yielding proceeding under mild conditions and is remarkably chemoselective leaving the CC bonds intact.

Palladium-Catalyzed Fluorinative Bifunctionalization of Aziridines and Azetidines with gem-Difluorocyclopropanes

An unprecedented Pd-catalyzed fluorinative bifunctionalization of aziridines and azetidines was successfully developed via regioselective C-C and C-F bond cleavage of gem-difluorocyclopropanes, leading to various β,β'-bisfluorinated amines and β,γ-bisfluorinated amines. This reaction was achieved by incorporating a 2-fluorinated allyl group and a fluorine atom scissored from gem-difluorocyclopropane in 100 % atom economy for the first time. The mechanistic investigations indicated that the reaction underwent amine attacking 2-fluorinated allyl palladium complex to generate η2 -coordinated N-allyl aziridine followed by fluoride ligand transfer affording the final β- and γ-fluorinated amines.

Accessing para-Alkylphenols via Iridium-Catalyzed Site-Specific Deoxygenation of Alcohols

An iridium-catalyzed and phenol-directed deoxygenation of benzylic alcohols comes as an alternative access to 4-alkylphenols, featuring low catalyst loading (S/C up to 20,000, TOF up to 12,400 h-1), high functionality compatibility, and excellent site-selectivity. The applications in late-stage modification of steroids and gram-scale total synthesis of a Gastrodia elata extract are highlighted. Mechanistically, the intermediacy of quinone methide controls the site-selectivity, and the formation of iridium hydride serves as the rate-limiting step.

Metal-free synthesis and study of glycine betaine derivatives in water for antimicrobial and anticancer applications

A sustainable synthesis of interesting glycine betaine derivatives from cyclic 3°-amines viz. N-methyl morpholine (NMM), N-methyl piperidine (NMP), and 1,4-diazabicyclo[2.2.2]octane (DABCO) with numerous aryl diazoacetates 1 in water and under blue LED is reported. Generally, 3°-amines and metal carbenoids (from diazoacetates with transition metal catalysts) provide C-H insertion at the α-position of the amines. Computational comparison of the metal carbenoid with the singlet carbene (metal free and generated under blue LED) realized the difference in reactivity. Next, experimental results corroborated the preliminary findings. The products were isolated either by precipitation of the solid or gel-like final products from the aqueous reaction mixture without any chromatographic purification. The reaction mechanism was realized by control experiments. These compounds exhibit selective bactericidal properties against Gram-positive S. aureus, induce lipid droplets (LDs) formation in HePG2 cells and single crystal X-ray diffraction study of their halogenated analogs reveal interesting Hal … Hal contacts.

Theoretical Study on the Copper-Catalyzed ortho-Selective C-H Functionalization of Naphthols with α-Phenyl-α-Diazoesters

The aromatic C(sp²)-H functionalization of unprotected naphthols with α-phenyl-α-diazoesters under mild conditions catalyzed by CuCl and CuCl₂ exhibits high efficiency and unique ortho-selectivity. In this study, the combination of density functional theory (DFT) calculations and experiments is employed to investigate the mechanism of C-H functionalization, which reveals the fundamental origin of the site-selectivity. It explains that CuCl-catalyzed ortho-selective C-H functionlization is due to the bimetallic carbene, which differs from the reaction catalyzed by CuCl₂ via monometallic carbene. The results demonstrate the function of favourable H-bond interactions on the site- and chemo-selectivity of reaction through stabilizing the rate-determining transition states in proton (1,3)-migration.

B(C6F5)3-catalyzed cyclopropanation of 3-alkenyl-oxindoles with diazomethanes

Spirocyclopropane-oxindoles are key motifs in biologically active compounds and are versatile synthetic intermediates. Herein, we report a metal-free, B(C₆F₅)₃ catalyzed cyclopropanation of 3-alkenyl-oxindoles with diazomethanes. This provides 25 variants of spirocyclopropane-oxindole derivatives. These spirocyclopropane-oxindole products were obtained in good to excellent yields (up to 99%) and high diastereoselectivities (up to 20 : 1 d.r.) under mild reaction conditions and could be performed on a gram scale.

Chemodivergent C(sp3)-H and C(sp2)-H Cyanomethylation Using Engineered Carbene Transferases

The ubiquity of C-H bonds presents an attractive opportunity to elaborate and build complexity in organic molecules. Methods for selective functionalization, however, often must differentiate among multiple chemically similar and, in some cases indistinguishable, C-H bonds. An advantage of enzymes is that they can be finely tuned using directed evolution to achieve control over divergent C-H functionalization pathways. Here, we demonstrate engineered enzymes that effect a new-to-nature C-H alkylation with unparalleled selectivity: two complementary carbene C-H transferases derived from a cytochrome P450 from Bacillus megaterium deliver an α-cyanocarbene into the α-amino C(sp3)-H bonds or the ortho-arene C(sp2)-H bonds of N-substituted arenes. These two transformations proceed via different mechanisms, yet only minimal changes to the protein scaffold (nine mutations, less than 2% of the sequence) were needed to adjust the enzyme's control over the site-selectivity of cyanomethylation. The X-ray crystal structure of the selective C(sp3)-H alkylase, P411-PFA, reveals an unprecedented helical disruption which alters the shape and electrostatics in the enzyme active site. Overall, this work demonstrates the advantages of enzymes as C-H functionalization catalysts for divergent molecular derivatization.

Efficient Synthesis of Diaryl Quaternary Centers by Rh(II)/Xantphos Catalyzed Relay C-H Functionalization and Allylic Alkylation

A three-component reaction of N, N-disubstituted aniline, α-diazo ester, and an allylic electrophile has been realized by [Rh(II)]₂ /Xantphos catalysis, providing a direct access to various aniline derivatives bearing diaryl allylic quaternary centers in good yields. The synthetic utility of this protocol was demonstrated by facile derivatization of the products for preparation of biologically relevant molecules and structural scaffolds, which offers a high potential for increasing the molecular diversity. Mechanistic studies identified α, α-diarylacetate species as an active intermediate, thereby revealing the presence of a C(sp² )-H functionalization of aniline derivatives/allylic alkylation cascade in this attractive catalytic transformation.

A rhodium-catalyzed ylide formation/Smiles rearrangement reaction of chalcogenide ether and triazoles

A Rh(ii)-catalyzed highly stereoselective chalcogenide ylide formation/Smiles rearrangement reaction of diaryl thioether/selenoethers and triazoles was successfully developed.

Aqueous C-H aminomethylation of phenols by iodine catalysis

A transition-metal-free strategy regarding an iodine-sodium percarbonate catalysis to achieve the ortho-aminomethylation of phenols in aqueous media has been developed. This method can effectively broaden a wide range of phenols, tolerate sensitive functional groups, and achieve the late-stage functionalization of ten functional molecules that contain phenolic structures.

Highly Site-Selective Direct C-H Bond Functionalization of Unactivated Arenes with Propargyl α-Aryl-α-diazoacetates via Scandium Catalysis

Highly chemo- and regio-selective C-H bond functionalization of unactivated arenes with propargyl α-aryl-α-diazoacetates has been developed using scandium catalysis. A variety of unactivated, mildly deactivated, and electronically activated arenes have been functionalized using this protocol. The synergistic combination of scandium triflate as a catalyst and propargyl α-aryl-α-diazoacetate as a reagent played a pivotal role in the effective C-H bond functionalization of arenes without the assistance of any directing group or ligand. The practicality of the protocol has been demonstrated by the gram-scale synthesis of very useful α,α-diarylacetates including antispasmodic drug-adiphenine. Based on the experimental observations, labeling experiment, and density functional theory calculations, a plausible reaction mechanism has been outlined.

Photocatalytic para-Selective C-H Functionalization of Anilines with Diazomalonates

Visible-light-induced para-selective C-H functionalization of anilines over N-H insertion was developed using diazomalonates with the help of an Ir(III) photocatalyst. The para-selective radical-radical cross coupling proceeded via C-centered radical intermediates generated from both anilines and diazomalonates. The photochemistry of anilines could be extended to other N-heterocycles, such as indole and carbazole. The reaction pathway for the selective C-C coupling was validated by electrochemical and photophysical experiments as well as computational studies.

Photocatalytic 1,2-oxo-alkylation reaction of styrenes with diazoacetates

We report on the photocatalytic 1,2-difunctionalization reaction of styrenes with acceptor-only diazoalkanes. In the presence of DABCO and tBuOOH, the carbene reactivity of diazoalkanes can be suppressed and a 1,2 oxo-alkylation reaction can be achieved (32 examples, up to 94% yield) without the formation of cyclopropane by-products via the formation of radical intermediates from ethyl diazoacetate.

Diastereoselective aldol-type interception of phenolic oxonium ylides for the direct assembly of 2,2-disubstituted dihydrobenzofurans

A Rh₂(OAc)₄ catalyzed intermolecular aldol-type interception of phenolic oxonium ylides with isatins has been developed, which provides an effective access to 2,2-disubstituted dihydrobenzofuran derivatives containing 3-hydroxyoxindole in high yields and with high diastereoselectivities under mild reaction conditions. The antiproliferation activity of these synthesized dihydrobenzofuran and 3-hydroxyoxindole hybrid products has been tested via the CCK8 assay in different cancer cell lines; compounds 3s and 3t exhibit good anticancer potency against human colon cancer cells (HCT116 cells, 3s: IC₅₀ = 15.99 μM; 3t: IC₅₀ = 14.48 μM) compared to other tested compounds.

Borane-catalyzed arylation of aryldiazoacetates with N,N-dialkylanilines

A selective arylation of donor-acceptor diazo compounds with aniline derivatives catalyzed by Lewis acidic boranes is developed. This simple reaction protocol provides an efficient method for the synthesis of diarylacetates under metal-free conditions.

Selective Functionalization of Arene C(sp2)–H Bonds by Gold Catalysis: The Role of Carbene Substituents

The complete regioselective incorporation of carbene units to nonactivated arene rings has been achieved employing gold(I) catalysts bearing alkoxydiaminophosphine ligands, with readily available, nonelaborated ethyl 2-phenyldiazoacetate as the carbene source. These results are in contrast with the scarce precedents which required highly elaborated diazo substrates. Density functional theory (DFT) calculations have revealed the important role of the R group in the C(R)CO₂Et fragment, which dramatically affects the energy profile of this transformation.

Overcoming O-H Insertion to Para-Selective C-H Functionalization of Free Phenols: Rh(II)/Xantphos Catalyzed Geminal Difunctionalization of Diazo Compounds

Para-selective C-H functionalization of free phenols by metal carbenoids is rather challenging due to the generally more favorable competing O-H insertion. Herein, with the use of the combination of Rh(II) and a Xantphos ligand as the catalyst, a novel multicomponent reaction of free phenols, diazoesters, and allylic carbonates was successfully developed, affording a wide variety of phenol derivatives, bearing an all-carbon quaternary center and a synthetically useful allylic unit. This reaction is likely to occur through a tandem process of carbene-induced para-selective C-H functionalization, followed by Rh(II)/Xantphos-catalyzed allylation. The distinctive reactivity of para-selective C-H rather than O-H insertion for the carbenoid intermediate, combined with features of excellent functional group compatibility, high atom and step economy, and ease in further diversification of the products, might render this protocol highly attractive in facile functionalization of unprotected phenols.

Asymmetric Arylation of Diazoesters with Anisoles Enabled by Cooperative Gold and Phosphoric Acid Catalysis

An enantioselective insertion of a carbene into the Csp²-H bond of anisole derivatives has been accomplished using an achiral gold complex and a chiral phosphoric acid as the catalytic system, providing a novel protocol for the synthesis of chiral α,α-diaryl acetates. Density functional theory calculations reveal the reactivity and the origin of the enantioselectivity of this reaction.

Cobalt-Catalyzed Regioselective para-Amination of Azobenzenes via Nucleophilic Aromatic Substitution of Hydrogen

The metal-catalyzed nucleophilic aromatic substitution of hydrogen (S_NArH) via coordination of the substituent on the aromatic ring to the metal catalyst, in terms of reactivity, substrate type, and reaction selectivity, complements the transition metal-catalyzed C-H functionalization that proceeds via C-H metalation but remains an elusive target. Described herein is the development of an unprecedented cobalt-catalyzed para-selective amination of azobenzenes, which is essentially a metal-promoted S_NArH process as revealed by Hammett analysis, thus illustrating the concept that coordination of the substituent on the arene ring to the metal catalyst may result in electrophilic activation of the arene ring toward S_NArH. This cobalt-catalyzed protocol allows the use of a variety of both aliphatic amines and anilines as aminating reagents, tolerates electronically diverse substituents of azobenzene, and furnishes the corresponding products in good yields with a regiospecific selectivity for para-amination.

Recent advances in transition-metal-catalyzed carbene insertion to C-H bonds

C-H functionalization has been emerging as a powerful method to establish carbon-carbon and carbon-heteroatom bonds. Many efforts have been devoted to transition-metal-catalyzed direct transformations of C-H bonds. Metal carbenes generated in situ from transition-metal compounds and diazo or its equivalents are usually applied as the transient reactive intermediates to furnish a catalytic cycle for new C-C and C-X bond formation. Using this strategy compounds from unactivated simple alkanes to complex molecules can be further functionalized or transformed to multi-functionalized compounds. In this area, transition-metal-catalyzed carbene insertion to C-H bonds has been paid continuous attention. Diverse catalyst design strategies, synthetic methods, and potential applications have been developed. This critical review will summarize the advance in transition-metal-catalyzed carbene insertion to C-H bonds dated up to July 2021, by the categories of C-H bonds from aliphatic C(sp³)-H, aryl (aromatic) C(sp²)-H, heteroaryl (heteroaromatic) C(sp²)-H bonds, alkenyl C(sp²)-H, and alkynyl C(sp)-H, as well as asymmetric carbene insertion to C-H bonds, and more coverage will be given to the recent work. Due to the rapid development of the C-H functionalization area, future directions in this topic are also discussed. This review will give the authors an overview of carbene insertion chemistry in C-H functionalization with focus on the catalytic systems and synthetic applications in C-C bond formation.

BF3·OEt2 catalyzed decarbonylative arylation/C-H functionalization of diazoamides with arylaldehydes: synthesis of substituted 3-aryloxindoles

A metal-free BF₃·OEt₂ catalyzed direct decarbonylative arylation of diazoamides with readily accessible aryl aldehydes under an open-air atmosphere was developed to afford 3-aryloxindoles via 1,2-aryl migration with high selectivity. The reaction offers an efficient pathway for 3-arylation of diazoamides under relatively mild conditions, which shows a high level of functional group tolerance of both electron-donating and electron-withdrawing groups with a broad substrate scope. 3-Aryloxindoles were also obtained by a substituent-controlled chemo- and site-selective C-H bond functionalization of unprotected salicylaldehyde derivatives.

Highly Stereoselective Synthesis of Tetrasubstituted Vinyl Selenides via Rhodium-Catalyzed [1,4]-Acyl Migration of Selenoesters and Diazo Compounds

Herein, we disclose a highly stereoselective Rh(II)-catalyzed 1,4-acyl rearrangement of selenium esters and α-diazo carbonyl compounds, which provides an efficient method for synthesizing tetrasubstituted vinyl selenides. Furthermore, this reaction also offers a synthetic tool for medium and large ring compounds.

Nickel-catalyzed para-selective carboxylation of phenols with CBr4/MeOH

1,10-Phenanthroline-assisted, Ni(ii)-catalyzed para-carboxylation of phenol derivatives is reported.

Nickel/Brønsted acid dual-catalyzed regioselective C–H bond allylation of phenols with 1,3-dienes

A nickel/Brønsted acid dual-catalyzed C-H bond ortho-allylation of phenols with 1,3-dienes has been developed. This methodology is readily applicable to the modification of complex pharmaceutical molecules.

Site-selective rhodium carbene transfer of 2 hydroxy-β-nitrostyrenes with diazo compounds En route to 2-alkylated benzofurans

The Rh(iii)-catalysed cascade vinylic C–H functionalization/carbene transfer/Michael addition sequence of 2-hydroxy-β-nitrostyrenes has been realized, delivering the 2-alkylated benzofuran derivatives as potential tyrosinase inhibitors.

Theoretical study on the mechanism, chemo- and enantioselectivity of the Ag- vs. Rh-catalyzed intramolecular carbene transfer reaction of diazoacetamides

DFT calculations reveal the mechanism, as well as the origins of chemoselectivity and enantioselectivity in the Ag vs. Rh catalyzed intramolecular carbene transfer reaction.

Modular and stereoselective synthesis of tetrasubstituted vinyl sulfides leading to a library of AIEgens

Tetraarylethylenes exhibit intriguing photophysical properties and sulfur atom frequently play a vital role in organic photoelectric materials and biologically active compounds. Tetrasubstituted vinyl sulfides, which include both sulfur atom and tetrasubstituted alkenes motifs, might be a suitable skeleton for the discovery of the new material molecules and drug with unique functions and properties. However, how to modular synthesis these kinds of compounds is still challenging. Herein, a chemo- and stereo-selective Rh(II)-catalyzed [1,4]-acyl rearrangements of α-diazo carbonyl compounds and thioesters has been developed, providing a modular strategy to a library of 63 tetrasubstituted vinyl sulfides. In this transformation, the yield is up to 95% and the turnover number is up to 3650. The mechanism of this reaction is investigated by combining experiments and density functional theory calculation. Moreover, the "aggregation-induced emission" effect of tetrasubstituted vinyl sulfides were also investigated, which might useful in functional material, biological imaging and chemicalnsing via structural modification.

Gold catalyzed efficient preparation of dihydrobenzofuran from 1,3-enyne and phenol

A gold catalyzed formal intermolecular [2+3] cyclo-coupling of 1,3-enynes with phenols was developed to prepare dihydrobenzofuran derivatives with the addition of 2,6-dichloropyridine N-oxide, in which, a highly ortho-selective phenol S_EAr functionalization was achieved by using 1,3-enynes as α-oxo vinyl gold carbenoid surrogates.

Gold(I)-Catalyzed Oxidative Amination of β-Amino-ynones to Quaternary Ammonium-olate Salts: The Benefit of a P,N-Bidentate Ligand

A novel P,N-bidentate ligand-assisted gold-catalyzed oxidative amination of β-amino-ynones has been developed, allowing the simple and efficient construction of various quaternary ammonium-olate salts in good to excellent yields. These unprecedented quaternary ammonium-olate salts can be isolated and purified via simple suction filtration. The broad substrate scope, easy purification, easy further transformation, and mild conditions make it a viable alternative for the synthesis of various quaternary ammonium-olate salts.