NHC–AuCl/Selectfluor: A Highly Efficient Catalytic System for Carbene-Transfer Reactions

The combination of NHC–gold complex and Selectfluor has been found to be a highly efficient catalyst system for carbene-transfer reactions, with a turnover number (TON) up to 990000 and a turnover frequency (TOF) up to 82500 h^–1

Ruthenium-Catalyzed Dehydrogenative β‑Benzylation of 1,2,3,4-Tetrahydroquinolines with Aryl Aldehydes: Access to Functionalized Quinolines

A new benzylation protocol, enabling straightforward access to β-benzylated quinolines, has been demonstrated. By employing readily available [RuCl₂(<i>p</i>-cymene)]₂ as a catalyst and O₂ as a sole green oxidant, various 1,2,3,4-tetrahydro­quinolines were efficiently converted in combination with aryl aldehydes into desired products in a step- and atom-economic fashion together with the advantages of excellent functional group tolerance and chemoselectivity, offering an important basis for the transformation of saturated <i>N</i>-heterocycles into functionalized <i>N</i>-heteroaromatics via a dehydrogenative cross-coupling strategy. Mechanistic investigations support that the reaction undergoes a monodehydrogenation-triggered β-benzylation mode

Access to C(sp³)–C(sp²) and C(sp²)–C(sp²) Bond Formation via Sequential Intermolecular Carbopalladation of Multiple Carbon–Carbon Bonds

A synthetic strategy of 4-benzyl-substituted 1,3-butadiene derivatives through Pd-catalyzed three-component coupling reaction of benzyl chlorides, alkynes, and monosubstituted alkenes is described. This tandem coupling reaction forms a C­(sp³)–C­(sp²) bond and a C­(sp²)–C­(sp²) bond sequentially in a single-step operation

Cu(II)-Catalyzed Synthesis of Naphthalene-1,3-diamine Derivatives from Haloalkynes and Amines

An efficient procedure for the preparation of naphthalene-1,3-diamine derivatives by copper-catalyzed haloalkynes with amines has been reported. The reaction was supposed to proceed through a coupling reaction followed by the dimerization of ynamines

Ruthenium-Catalyzed C–H Arylation of Aromatic Acids with <i>ortho</i>-Haloaniline To Access Phenanthridinones

Phenanthridinone is a significant moiety in pharmaceutical and material science; thus, it is highly desirable to develop an efficient and robust method to construct phenanthridinone from readily available starting materials. Herein, we report a Ru-catalyzed C–H arylation of aromatic carboxylic acids with ortho-haloanilines, followed by intramolecular dehydration to afford phenanthridinones in high yields

Synthesis of γ‑Thiapyrones by Diels–Alder/Retro-Diels–Alder Reaction of α‑Pyrones with 5‑<i>H</i>‑1,2,3-Thiadiazoles

The efficient synthesis of γ-thiapyrones by a base-mediated Diels–Alder/retro-Diels–Alder reaction of α-pyrones with 5-H-1,2,3-thiadiazoles is reported herein. Thioketenes in situ generated from thiadiazoles as electron-poor dienophile and electron-rich 4-hydroxy-2-pyrones as dienes are conjunctively transformed into a series of γ-thiapyrones with broad functional group compatibility in good to excellent yields (35 examples, 67% average yield)

Palladium-Catalyzed 1,2-Alkynylarylation of Vinyl Arenes with Haloalkynes and Arylboronic Acids

We herein disclose a novel palladium-catalyzed 1,2-alkynylarylation of vinyl arenes using haloalkynes and arylboronic acids as coupling partners. This reaction is characterized by broad substrate scope, controllable reaction sequence, and excellent chemo- and regioselectivities. Mechanistic investigations suggest that the reaction is initiated by regioselective insertion of vinyl arenes into the alkynyl-Pd(II) species, and the silver salt is crucial for this transformation, serving as both the Lewis acid and halide scavenger. This protocol provides efficient access to new carbon skeletons, which are embedded in the key biologically active motifs

Base-Mediated Three-Component Tandem Reactions for the Synthesis of Multisubstituted Pyrimidines

A base-mediated three-component tandem reaction for the synthesis of multisubstituted pyrimidines from amidines, aryl alkynes, and aldehydes in a one-pot manner has been developed. Advantages of this transformation include being transition-metal-free, high efficiency, available starting materials, and being environmentally friendly

Pd(II)-Catalyzed Sequential C–C/C–O Bond Formations: A New Strategy to Construct Trisubstituted Furans

Palladium-catalyzed oxidative difunctionalization of enol ethers with 1,3-dicarbonyl compounds to construct trisubstituted furans in one step under mild conditions is described. The reaction is thought to proceed through a C–C bond formation along with a C–O bond closing the ring structure. Oxygen is the sole oxidant regenerating the Pd(II) catalyst

Nucleopalladation Triggering the Oxidative Heck Reaction: A General Strategy to Diverse β‑Indole Ketones

A simple and efficient palladium-catalyzed oxidative coupling between 2-alkynyl anilines and allylic alcohols is described by using cheap and green dioxygen as the oxidant. These cross-couplings have a large functional group tolerance and are of higher reactivity toward electron nonbaised allylic alcohols. The resultant β-indole ketones are readily converted to pharmaceutically significant β-indole alcohol/amine and pyrrolo[2,1-<i>a</i>]isoquinolines