Metal-free arylation of pyrimidines through a photochemical process

Expedient Access to 18F-Fluoroheteroarenes via Deaminative Radiofluorination of Aniline-Derived Pyridinium Salts

Herein, we disclose that pyridinium salts derived from abundant (hetero)anilines represent a novel precursor class for nucleophilic aromatic substitution reactions with [18F]fluoride. The value of this new 18F-fluorodeamination is demonstrated with the synthesis of over 30 structurally diverse and complex heteroaryl 18F-fluorides, several derived from scaffolds that were yet to be labelled with fluorine-18. The protocol tolerates heteroarenes and functionalities commonly found in drug discovery libraries, and is amenable to scale-up and automation on a commercial radiosynthesiser.

One-pot synthesis of Ag-Cu-Cu2O/C nanocomposites derived from a metal-organic framework as a photocatalyst for borylation of aryl halide

Mixed metal-metal oxide/C (Ag-Cu-Cu2O/C) nanocomposites were synthesized by the heat treatment of a metal-organic framework under a N2 flow using the one-pot synthesis method. The as-prepared nanocomposites were characterized using a range of techniques, such as TEM, elemental mapping, XRD, N2 sorption, UV-Vis DRS, and XPS. The nanoparticles were successfully formed with high dispersion in porous carbon materials and high crystallinity based on the analysis results. The Ag-Cu-Cu2O/C nanocomposites (35 nm) showed high photocatalytic activity and good recyclability toward the borylation of aryl halides under a xenon arc lamp. This result can enhance the interest in photocatalysis for various applications, particularly in organic reactions, using a simple and efficient synthesis method.

Organoboron chemistry comes to light: recent advances in photoinduced synthetic approaches to organoboron compounds

Photoinduced synthetic approaches to organoboron compounds have attracted significant attention in the recent years. Photochemical activation of organic molecules enables generation of reactive intermediates from a variety of precursors, resulting in borylation methods with improved and broader substrate scopes. The review summarizes recent developments in the area of photoinduced reactions of organoboron compounds with an emphasis on borylation of haloarenes, amine derivatives, and redox-active esters of carboxylic acids, as well as photoinduced rearrangements of organoboron compounds and photoinduced synthesis of organoboron compounds from alkenes and alkynes.

A photoinduced reaction of perfluoroalkyl halides with 1,3-diarylprop-2-yn-1-ones catalyzed by DABSO

The sulfur dioxide surrogate of DABCO·(SO₂)₂ is used as an efficient catalyst for the cleavage of the perfluoroalkyl-halogen bond under visible-light irradiation. A plausible mechanism supported by theoretical calculations is proposed.

Additive- and Metal-Free, Predictably 1,2- and 1,3-Regioselective, Photoinduced Dual C-H/C-X Borylation of Haloarenes

We report herein a simple, additive- and metal-free, photoinduced, dual C-H/C-X borylation of chloro-, bromo-, and iodoarenes. The reaction produces 1,2- and 1,3-diborylarenes on gram scales under batch and continuous flow conditions. The regioselectivity of the dual C-H/C-X borylation is determined by the solvent and the substituents in the parent haloarenes.

Scalable, Metal- and Additive-Free, Photoinduced Borylation of Haloarenes and Quaternary Arylammonium Salts

We report herein a simple, metal- and additive-free, photoinduced borylation of haloarenes, including electron-rich fluoroarenes, as well as arylammonium salts directly to boronic acids. This borylation method has a broad scope and functional group tolerance. We show that it can be further extended to boronic esters and carried out on gram scale as well as under flow conditions.

Generation of N-aminosulfonamides via a photo-induced fixation of sulfur dioxide into aryl/alkyl halides

A catalyst-free aminosulfonylation through insertion of sulfur dioxide with aryl/alkyl halides enabled by photoenergy is presented. Under ultraviolet irradiation, a three-component reaction of aryl/alkyl halides, sulfur dioxide, and hydrazines proceeds under mild conditions without any metals or photo-redox catalysts.

A general route to fluorinated 3,3-disubstituted 2-oxindoles via a photoinduced radical cyclization of N-arylacrylamides under catalyst-free conditions

A catalyst-free radical cyclization of N-arylacrylamides with fluorinated alkyl iodides or the Togni reagent enabled by photoenergy is reported, leading to fluorinated 2-oxindoles in good yields. The broad reaction scope is demonstrated with good functional group tolerance.

Synthesis of trifluoromethylated 3,4-dihydroquinolin-2(1H)-ones via a photo-induced radical cyclization of benzene-tethered 1,7-enynes with Togni reagent

A photoinduced radical cyclization of benzene-tethered 1,7-enynes with Togni reagent in the presence of sodium iodide is developed. This transformation works well without any metals or photo-redox catalysts at room temperature.

Generation of (2-oxoindolin-3-yl)methanesulfonohydrazides via a photo-induced reaction of N-(2-iodoaryl)acrylamide, DABSO, and hydrazine

A photo-induced catalyst-free three-component reaction of N-(2-iodoaryl)acrylamide, sulfur dioxide, and hydrazine is reported. Under ultraviolet irradiation, diverse (2-oxoindolin-3-yl)methanesulfonohydrazides are generated in moderate to good yields.