Photochemically Mediated Nickel-Catalyzed Synthesis of N-(Hetero)aryl Sulfamides

2-Pyridone-Directed CuII-Catalyzed General Method of C(sp2)-H Activation for C-S, C-Se, and C-N Cross-Coupling: Easy Access to Aryl Thioethers, Selenide Ethers, and Sulfonamides and DFT Study

We have demonstrated N-substituted 2-pyridones as an N,O-directing group for selective C(sp2)-H-activated thiolation, selenylation, and sulfonamidation of ortho C-H bonds of benzamides. This method utilizes a cost-effective Cu(II)-salt catalyst instead of precious metal catalysts, achieving high yields, including gram-scale synthesis and excellent functional group tolerance. We applied this protocol to access 30 different compounds with high yields, demonstrating thiolation of fluorine-substituted benzamides as well. Density functional theory (DFT) calculations support the mechanism, including acetate-supported concerted metalation deprotonation (CMD) steps and the unique role of dimethyl sulfoxide (DMSO) solvent. The facile synthesis of pharmaceutically important sulfonamides and other compounds highlights the method's potential in chemistry and medicinal chemistry.

One-Flow Syntheses of Unsymmetrical Sulfamides and N-Substituted Sulfamate Esters

We developed one-flow syntheses of unsymmetrical sulfamides and N-substituted sulfamate esters by changing a nucleophile and a tertiary amine from inexpensive and commercially available chlorosulfonic acid. In the synthesis of N-substituted sulfamate esters, unexpected symmetrical sulfite formation was suppressed by changing the tertiary amine. The effect of tertiary amines was proposed using linear regression. Our approach rapidly (≤90 s) provides desired products containing acidic and/or basic labile groups without tedious purification under mild (20 °C) conditions.

Thermal Nickel-Catalyzed N-Arylation of NH-Sulfoximines with (Hetero)aryl Chlorides Enabled by PhPAd-DalPhos Ligation

We report a versatile method for cross-coupling of NH-sulfoximines with (hetero)aryl chlorides, as well as bromide and sulfonate electrophiles, that makes use of the air-stable, commercial precatalyst (PhPAd-DalPhos)Ni(o-tol)Cl. Under optimized conditions a diverse electrophile scope is established, including the N-arylation of the pharmaceutical Clozapine. While 5 mol % Ni and 80 °C are commonly employed in this chemistry, successful examples utilizing 1 mol % Ni and/or 25 °C are presented. Competition experiments establish the superiority of NH-sulfoximine over primary sulfonamide as nucleophiles under these conditions.

Directed Photochemically Mediated Nickel-Catalyzed (Hetero)arylation of Aliphatic C-H Bonds

Site-selective functionalization of unactivated C(sp3)-H centers is challenging because of the ubiquity and strength of alkyl C-H bonds. Herein, we disclose a position-selective C(sp3)-C(sp2) cross-coupling reaction. This process engages C(sp3)-H bonds and aryl bromides, utilizing catalytic quantities of a photoredox-capable molecule and a nickel precatalyst. Using this technology, selective C-H functionalization arises owing to a 1,6-hydrogen atom transfer (HAT) process that is guided by a pendant alcohol-anchored sulfamate ester. These transformations proceed directly from N-H bonds, in contrast to previous directed, radical-mediated, C-H arylation processes, which have relied on prior oxidation of the reactive nitrogen center in reactions with nucleophilic arenes. Moreover, these conditions promote arylation at secondary centers in good yields with excellent selectivity.

Comparative Screening of DalPhos/Ni Catalysts in C-N Cross-couplings of (Hetero)aryl Chlorides Enables Development of Aminopyrazole Cross-couplings with Amine Base

A systematic competitive evaluation of the DalPhos ligand family in nickel-catalyzed N-arylation chemistry is reported, involving primary (linear and branched) and secondary alkylamines, as well as a primary five-membered heteroarylamine (aminopyrazole), in combination with a diverse set of test electrophiles and bases (NaOtBu, K₂ CO₃ , DBU/NaTFA). In addition to providing optimal ligand/catalyst identification, and bringing to light methodology limitations (e. g., unwanted C-O cross-coupling with NaOtBu), our survey enabled the development of the first efficient catalyst system for heteroatom-dense C-N cross-coupling of aminopyrazoles and related nucleophiles with (hetero)aryl chlorides by use of an amine 'dual-base' system.

Synthesis, in silico study (DFT, ADMET) and crystal structure of novel sulfamoyloxy-oxazolidinones: Interaction with SARS-CoV-2

A new series of sulfamoyloxyoxazolidinone (SOO) derivatives have been synthesized and characterized by single-crystal X-ray diffraction, NMR, IR, MS and EA. Chemical reactivity and geometrical characteristics of the target compounds were investigated using DFT method. The possible binding mode between SOO and Main protease (Mpro) of SARS-CoV-2 and their reactivity were studied using molecular docking simulation. Single crystal X-ray diffraction showed that SOO crystallizes in a monoclinic system with P 2 1 space group. The binding energy of the SARS-CoV-2/Mpro-SOO complex and the calculated inhibition constant using docking simulation showed that the active SOO molecule has the ability to inhibit SARS-CoV2. We studied the prediction of absorption, distribution, properties of metabolism, excretion and toxicity (ADMET) of the synthesized molecules.

Mapping Dual-Base-Enabled Nickel-Catalyzed Aryl Amidations: Application in the Synthesis of 4-Quinolones

The C-N cross-coupling of (hetero)aryl (pseudo)halides with NH substrates employing nickel catalysts and organic amine bases represents an emergent strategy for the sustainable synthesis of (hetero)anilines. However, unlike protocols that rely on photoredox/electrochemical/reductant methods within Ni^I/III cycles, the reaction steps that comprise a putative Ni^0/II C-N cross-coupling cycle for a thermally promoted catalyst system using organic amine base have not been elucidated. Here we disclose an efficient new nickel-catalyzed protocol for the C-N cross-coupling of amides and 2'-(pseudo)halide-substituted acetophenones, for the first time where the (pseudo)halide is chloride or sulfonate, which makes use of the commercial bisphosphine ligand PAd2-DalPhos (L4) in combination with an organic amine base/halide scavenger, leading to 4-quinolones. Room-temperature stoichiometric experiments involving isolated Ni^{0, I, and II} species support a Ni^0/II pathway, where the combined action of DBU/NaTFA allows for room-temperature amide cross-couplings.

Strategies to Generate Nitrogen-centered Radicals That May Rely on Photoredox Catalysis: Development in Reaction Methodology and Applications in Organic Synthesis

For more than 70 years, nitrogen-centered radicals have been recognized as potent synthetic intermediates. This review is a survey designed for use by chemists engaged in target-oriented synthesis. This review summarizes the recent paradigm shift in access to and application of N-centered radicals enabled by visible-light photocatalysis. This shift broadens and streamlines approaches to many small molecules because visible-light photocatalysis conditions are mild. Explicit attention is paid to innovative advances in N-X bonds as radical precursors, where X = Cl, N, S, O, and H. For clarity, key mechanistic data is noted, where available. Synthetic applications and limitations are summarized to illuminate the tremendous utility of photocatalytically generated nitrogen-centered radicals.

Metal-catalyzed reactions for the C(sp2)–N bond formation: achievements of recent years

The review deals with the main catalytic methods for the C(sp2)–N bond formation, including Buchwald–Hartwig palladium-catalyzed amination of aryl and heteroaryl halides, renaissance of the Ullmann chemistry, i.e., the application of catalysis by copper complexes to form the carbon–nitrogen bond, and Chan–Lam reactions of (hetero)arylboronic acids with amines. Also, oxidative amination with C–H activation, which has been booming during the last decade, is addressed. Particular attention is paid to achievements in the application of heterogenized catalysts.

The bibliography includes 350 references.

Metallaphotoredox: The Merger of Photoredox and Transition Metal Catalysis

The merger of photoredox catalysis with transition metal catalysis, termed metallaphotoredox catalysis, has become a mainstay in synthetic methodology over the past decade. Metallaphotoredox catalysis has combined the unparalleled capacity of transition metal catalysis for bond formation with the broad utility of photoinduced electron- and energy-transfer processes. Photocatalytic substrate activation has allowed the engagement of simple starting materials in metal-mediated bond-forming processes. Moreover, electron or energy transfer directly with key organometallic intermediates has provided novel activation modes entirely complementary to traditional catalytic platforms. This Review details and contextualizes the advancements in molecule construction brought forth by metallaphotocatalysis.

Photophysical Properties and Redox Potentials of Photosensitizers for Organic Photoredox Transformations

Photoredox catalysis has proven to be a powerful tool in synthetic organic chemistry. The rational design of photosensitizers with improved photocatalytic performance constitutes a major advancement in photoredox organic transformations. This review summarizes the fundamental ground-state and excited-state photophysical and electrochemical attributes of molecular photosensitizers, which are important determinants of their photocatalytic reactivity.