A Palladium-Catalyzed α‑Arylation of Oxindoles with Aryl Tosylates

A palladium-catalyzed monoselective C3 arylation of 2-oxindoles with aryl tosylates is described. With the Pd/CM-phos catalyst system, the corresponding 3-arylated oxindoles can be obtained in good to excellent yields (≤97%). The reaction conditions are mild (using 0.5 mol % Pd in general and KF as a base), and functional groups such as methyl ester, NH amido, and enolizable keto moieties are found to be compatible

Palladium-Catalyzed <i>ortho</i>-CH-Bond Oxygenation of Aromatic Ketones

A palladium-catalyzed C_(sp2)–H bond oxygenation reaction is described. This protocol represents the first example of a C–H bond cleavage/C–O bond formation sequence, by employing a ketone moiety as the directing group. With this new catalytic method, a variety of <i>ortho</i>-acylphenols can be easily accessed from arylketones

Preparation of a Highly Congested Carbazoyl-Derived P,N-Type Phosphine Ligand for Acetone Monoarylations

We report a newly developed carbazoyl-derived P,N-type phosphine ligand (<b>L1</b>) for the monoarylation of acetone with aryl chlorides. The proposed Pd­(dba)₂/<b>L1</b> catalyst exhibited remarkable catalytic reactivity toward highly electron rich and sterically congested aryl chlorides, with catalyst loading as low as 0.1 mol % of Pd along with excellent chemoselectivity. A reaction rate study of the system using electronically diverse aryl chlorides determined the mechanisms regarding the rate-limiting steps in this reaction. The oxidative addition adduct of Pd-PhenCar-Phos with <i>p</i>-chlorotoluene showed the participation of N–Pd coordination in the metal complex. The isolated palladium complex <b>C1</b> could be utilized as a precatalyst in the transformation and achieved performance comparable to that of the in situ generated palladium species

Accessing Axially Chiral Biaryls via Organocatalytic Enantioselective Dynamic-Kinetic Resolution-Semipinacol Rearrangement

We have developed a synthetic strategy to access axially chiral biaryls through a dynamic-kinetic resolution-semipinacol rearrangement process. The axial chirality together with a sp³ quaternary carbon can be introduced in a single chemical operation. The products can be further ring-expanded to yield biologically relevant seven-membered dibenzolactams with inverted axial chirality

Copper-Catalyzed Oxidative C–H Amination of Tetrahydrofuran with Indole/Carbazole Derivatives

A simple α-C–H amination of cyclic ether with indole/carbazole derivatives has been accomplished by employing copper­(II) chloride/bipy as the catalyst system. In the presence of the di-<i>tert</i>-butyl peroxide oxidant, cyclic ethers such as tetrahydrofuran, 1,4-dioxane, and tetrahydropyran successfully undergo C–H/N–H cross dehydrogenative coupling (CDC) with various carbazole or indole derivatives in good-to-excellent yields

Design of an Indolylphosphine Ligand for Reductive Elimination-Demanding Monoarylation of Acetone Using Aryl Chlorides

The rational design of a phosphine ligand for the reductive elimination-demanding Pd-catalyzed mono-α-arylation of acetone is demonstrated and reported. The catalyst is tolerant of previously proven challenging electron-deficient aryl chlorides and provides excellent product yields with down to 0.1 mol % Pd. Preliminary investigations suggest that the rate-limiting step for the proposed system is the oxidative addition of aryl chlorides, in which it contradicts previous findings regarding the α-arylation of acetone with aryl halides

Intramolecular Direct C–H Bond Arylation from Aryl Chlorides: A Transition-Metal-Free Approach for Facile Access of Phenanthridines

A C–H arylation with aryl chloride is made viable through a transition-metal-free approach. In the presence of a simple diol associating with KO<i>t</i>-Bu, various phenanthridine derivatives can be conveniently accessed. In particular, only 10 mol % of simple and inexpensive ethylene glycol is required for this protocol. These results represent the first general examples of aryl chloride/C–H coupling under transition-metal-free conditions

Cascade Amination and Acetone Monoarylation with Aryl Iodides by Palladium/Norbornene Cooperative Catalysis

A palladium/norbornene cocatalyzed three-component reaction of aryl iodides, <i>O</i>-benzoylhydroxylamines, and acetone is reported. <i>o</i>′-Aminoaryl acetones or <i>o</i>,<i>o</i>′-diaminoaryl acetones are efficiently prepared via tandem <i>ortho</i>-C–H amination/<i>ipso</i>-C–I α-arylation sequence, and the regiospecificity has been confirmed by X-ray analysis. The proposed method addresses the condensation/amination of free-<i>N</i>-H-bearing substrates in acetone monoarylations and the synthesis of extremely congested 2,6-disubstituted aryl acetones

Synthesis of 3‑Cyanoindole Derivatives Mediated by Copper(I) Iodide Using Benzyl Cyanide

Copper-mediated direct and regioselective C3-cyanation of indoles using benzyl cyanide as the cyanide anion source is presented. A wide range of indoles undergo cyanation smoothly by employing a reaction system of copper­(I) iodide under open-to-air vessels

Carbon–Boron Bond Cross-Coupling Reaction Catalyzed by −PPh₂ Containing Palladium–Indolylphosphine Complexes

This study describes the application of indolylphosphine ligands with a diphenylphosphino moiety to the palladium-catalyzed borylation of aryl chlorides. The combination of palladium metal precursor with PPh₂-Andole-phos, which comprises an inexpensive −PPh₂ group, provides highly effective catalysts for the borylation of aryl chlorides. A range of functional groups such as −CN, −NO₂, −CHO, −COMe, −COOMe, and −CF₃ was compatible, and the catalyst loading down to 0.025 mol % of Pd can be achieved. The Pd/PPh₂-Andole-phos system is able to catalyze both borylation reaction and Suzuki–Miyaura coupling reaction in a one-pot sequential manner for the direct synthesis of biaryl compounds in excellent yields