Ruthenium-Catalyzed C–H Arylation of Diverse Aryl Carboxylic Acids with Aryl and Heteroaryl Halides

Ruthenium ligated to tricyclohexylphosphine or di-<i>tert</i>-butylbipyridine catalyzes the arylation of carboxylic acids with diverse aryl halides (iodide, bromide, and triflate; aryl and heteroaryl). In addition, arylations with 2-iodophenol formed benzochromenones, carboxylate was shown to be a stronger donor than an amide, and the arylation of a pyridine carboxylate was demonstrated. Stoichiometric studies demonstrated that the added ligand is required for reaction with the electrophile but not the C–H bond

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

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)

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

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

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

Synthesis of δ-Bromo γ,δ-Unsaturated Carbonyl Compounds via Palladium-Catalyzed Bromoalkylation of Alkynoates

Palladium-catalyzed regio- and stereoselective intermolecular tandem reaction of electron-deficient alkynes, CuBr₂, and allylic alcohol to synthesize δ-bromo-γ,δ-unsaturated carbonyls was developed. A mechanism involving bromopalladation of alkyne, followed by insertion of allylic alcohol and allylic hydrogen shift, is proposed. The shift of allylic hydrogen is the rate-limiting step in this reaction

Palladium-Catalyzed Oxidative Annulation of Acrylic Acid and Amide with Alkynes: A Practical Route to Synthesize α‑Pyrones and Pyridones

A range of internal alkynes smoothly underwent palladium-catalyzed oxidative annulations with acrylic acid and amide to afford α-pyrones and pyridones in good to excellent yields with high regioselectivity. The usage of O₂ (1 atm) as a stoichiometric oxidant with H₂O as the only byproduct under mild conditions makes this process more attractive and practical

Nucleopalladation-Initiated Oxyalkenylation of Alkenes: A Strategy To Construct Functionalized Oxygenated Heterocycles

A convenient and efficient approach to construct functionalized oxygen heterocycles, i.e., tetrahydrofurans, tetrahydropyrans, and γ-lactones, has been reported. This process successfully provides a route to construct derivatives of naturally occurring biologically active tetrahydrofurans, especially ones with spirocyclic structure. Highly regio- and stereoselective nucleopalladation of alkynes initiates the cross-coupling between alkynamides and alkenes to give the olefin oxyalkenylation products in good to excellent yields. The hydroxyl group in the olefins cooperates with the amide in alkynamides to promote the cyclization by suppressing the β-H elimination

Highly Selective β‑Hydride Elimination in Pd-Catalyzed Decarboxylative Heck-Type Reaction

A variety of β-aryl ketones and aldehydes were facilely synthesized via a Pd(II)/Ag₂CO₃-mediated decarboxylative Heck type reaction between readily available benzoic acid derivatives and allylic alcohols under mild conditions. The control experiments indicated that this transformation may proceed via a hydrogen migration process