Metal-Free Electrochemical Allylic C-H Aerobic Oxidation.

A scalable and sustainable electrochemical protocol for allylic C-H aerobic oxidation has been developed, enabling the formation of enones without the use of stoichiometric toxic oxidants or metal catalysts and offering an environmentally benign alternative to traditional chemical oxidation techniques. The process has been successfully applied to selectively oxidize a series of natural products and drug molecules, underscoring its potential for widespread adoption in both academic and industrial contexts.

Electrochemical Synthesis of Vinyl, Alkyl, and Allyl Sulfones from Sodium Sulfinates and Olefins.

An electrochemical synthesis of vinyl, alkyl, and allyl sulfones using sodium sulfinates and olefins was reported. This method uses direct current to pass through an undivided cell equipped with graphite carbon electrodes, and a series of diverse sulfone compounds can be synthesized at room temperature in high yields.

A Recyclable Electrochemical Reduction of Aldehydes and Ketones to Alcohols Using Water as the Hydrogen Source and Solvent.

There are several challenging problems such as the usage of combustible and hazardous hydrogen sources and severe environmental pollution in the conventional reduction of aldehydes/ketones to alcohols. We report here a practical, safe, and green electrochemical reduction, which solves these problems to a large extent. Through an undivided cell, Zn(+) and Sn(-) as the electrode, tetrabutylammonium chloride (TBAC) as the electrolyte, water as the solvent and hydrogen source, a wide range of aldehydes and ketones are converted into the corresponding alcohols in mild conditions.

Radical Three-Component Nitro Spiro-Cyclization of Unsaturated Sulfonamides/Amides to Access NO-Featured 4-Azaspiro[4.5]decanes.

Free radical three-component nitration/spirocyclization of unsaturated sulfonamides/amides with -butyl nitrite was developed for the construction of diverse NO-revised 4-azaspiro[4.5]decanes. This tandem system featured metal-free participation, simple operation, good selectivity/yields, and a green/low-cost O source.

Metal-free radical bicyclization/chloroalkylarylation of 1,6-enynes with chloroalkanes.

Free radical initiated bicyclization of 1,6-enynes with chloralkanes, is achieved selective activation of the C(sp)-H bond of the chloralkane, resulting in diverse polychlorinated/chlorinated polyheterocycles. Two kinds of transformations and a scaled-up experiment were performed to test the synthetic importance of the organic chlorides. Finally, a range of radical inhibition operations and radical clock tests were explored to support the reaction process.

A free radical nitration of olefins with NaNO/IO.

We demonstrated herein an IO-mediated radical nitration of olefins with NaNO. A variety of ()-nitroolefins can be synthesized in high yields and chemoselectivity.

Photoinduced Tandem Cyanomethylation/Cyclization of Unsaturated Compounds: Access to Cyanomethylated 7- or 5-Membered -Heterocycles.

A cyanomethylation/cyclization of aryl acetylenes/ethylenes with bromoacetonitrile was finished in a photopromoted condition, which offers an efficient and mild protocol for the preparation of cyanomethylated 7- or 5-membered -heterocycles with good yields. Meanwhile, trichloroacetonitrile was also compatible with this radical pathway. In addition, a variety of single-crystal X-ray diffraction measurements, scaled-up operations to 1 mmol, functional group transformations of final products, light on/off experiments, and even radial inhibition studies were smoothly performed in this tandem system.

Nitro-Spirocyclization of Biaryl Ynones with -Butyl Nitrite: Access to NO-Substituted Spiro[5,5]trienones.

A metal/peroxide-free involved simple cascade 6--trig spirocyclization of -butyl nitrite with biaryl ynones has been finished, which resulted in various NO-modified spiro[5,5]trienones with good regioselectivity/yields. A variety of scaled-up experiments, reduction/epoxidation operations, and mechanistic studies were performed to verify the merits and spirocyclization process of this radical system. Finally, the structure of the spirocycles was confirmed by single-crystal X-ray diffraction.

Palladium-catalyzed C(sp)-H nitrooxylation of masked alcohols.

A palladium-catalyzed β-C(sp)-H nitrooxylation of aliphatic alcohols with AgNO is reported. An 8-formylquinoline-derived oxime is installed as an -type directing group for sp C-H activation and selectfluor acts as the oxidant. The reaction tolerates a variety of functional groups and shows good selectivity for β-C-H nitrooxylation of alcohols.

Free Radical Promoted Trifluoromethylthiolation of Alkynes to Access SCF-Containing Dibenzazepines or Dioxodibenzothiazepines.

Persulfate-promoted radical cascade trifluoromethylthiolation of aryl acetylenes with AgSCF provides a simple reaction system for the synthesis of SCF-substituted dibenzazepines or dioxodibenzothiazepines with good / selectivity. The single-crystal X-ray diffraction data confirms the structures of the final products. A series of scaled-up experiments, further transformations, and radical inhibition experiments were operated in the reaction system.

Electrochemical Aerobic Oxidative Cleavage of (sp)C-C(sp)/H Bonds in Alkylarenes.

An electrochemistry-promoted oxidative cleavage of (sp)C-C(sp)/H bonds in alkylarenes was developed. Various aryl alkanes can be smoothly converted into ketones/aldehydes under aerobic conditions using a user-friendly undivided cell setup. The features of air as oxidant, scalability, and mild conditions make them attractive in synthetic organic chemistry.

Free Radical-Promoted Monochloroalkylarylation of Alkenes with Chloralkanes.

Free radical-initiated cascade cyclization of unactivated alkenes with chloralkanes, which undergoes selective activation of the α-C(sp)-H bond of chloralkanes, provides a protocol for the synthesis of chlorinated heterocycles or polycyclic compounds. A series of radical inhibition experiments, radical capture operations, and radical clock tests were studied in this system.

Site-Specific Oxidation of (sp)C-C(sp)/H Bonds by NaNO/HCl.

A site-specific oxidation of (sp)C-C(sp) and (sp)C-H bonds in aryl alkanes by the use of NaNO/HCl was explored. The method is chemical-oxidant-free, transition-metal-free, uses water as the solvent, and proceeds under mild conditions, making it valuable and attractive to synthetic organic chemistry.

Free-Radical-Promoted Dehydrogenative Coupling of Polyfluorinated Alcohol with Quinone, Chromone, and Coumarin.

A free-radical-mediated dehydrogenative cross-coupling reaction of polyfluorinated alcohol with quinone, coumarin, and chromone was developed. It provides a sustainable and practical strategy for installation of fluorine atom into organic molecules by using polyfluorinated alcohols.

Free Radical Addition of Nitrile, Ketone, and Ester to Alkyne and the Selectivity Discussion.

A general and practical atom transfer radical addition (ATRA) of simple nitriles, ketones, and esters to alkynes was developed. It can allow an efficient access to a wide range of β,γ-unsaturated nitriles, ketones, and esters. The unique chemoselectivity in this system is also discussed.

Atom-Transfer Radical Addition of Alcohols to Aliphatic Alkynes.

An intermolecular hydrogen bond-promoted atom-transfer radical addition of simple alcohols to aliphatic alkynes is demonstrated here. Through this strategy, a variety of allyl alcohols can be synthesized in high selectivity and yields. Furthermore, this work reveals the relationship between selectivity and the substrate.

A free radical alkylation of quinones with olefins.

We demonstrated herein an Fe(iii)-mediated radical alkylation of quinones. A wide range of bioactive molecules with quinone motifs can be rapidly synthesized by using readily available and inexpensive NaBH4/NaBD4 with alkenes at room temperature under open flask conditions.

Molecular Oxygen-Promoted General and Site-Specific Alkylation with Organoboronic Acid.

A general alkylating method using organoboronic acid under 1 atm of oxygen is developed. It allows a facile access to a wide range of functionalized molecules with privileged scaffolds in drugs and natural products such as oxindoles, quinolinones, chromones, naphthoquinones, coumarins, and quinolones. In contrast to previous alkylation approaches that generally requiring transition-metal catalysis and a stoichiometric chemical oxidant, the present strategy features metal-free, molecular oxygen as the terminal oxidant and site specificity.

Molecular Oxygen-Mediated Minisci-Type Radical Alkylation of Heteroarenes with Boronic Acids.

The carbon-carbon bond formation via autoxidation of organoboronic acid using 1 atm of O is achieved in a simple, clean, and green fashion. The approach allows a technically facile and environmentally benign access to structurally diverse heteroaromatics with medicinally privileged scaffolds. The strategy also displays its practicality and sustainability in the resynthesis of marketed drugs Crestor and pyrimethamine.

A Fe(III)/NaBH-Promoted Free-Radical Hydroheteroarylation of Alkenes.

A free-radical-mediated intermolecular hydroheteroarylation of simple alkenes was developed. Through simply mixing heteroarenes, alkenes, Fe(III), and NaBH at 0 °C together, a wide range of alkylated heteroarenes could be afforded in moderate to excellent yields within 1 h.

Free-Radical-Promoted Site-Selective C-H Silylation of Arenes by Using Hydrosilanes.

A free-radical-promoted aryl/heteroaryl C-H silylation using hydrosilane was developed. This cross-dehydrogenative silylation enables both electron-rich and electron-poor aromatics to afford the desired arylsilanes in unique selectivity. A "para-selectivity" was observed by examination of over 54 examples.

An Intermolecular Azidoheteroarylation of Simple Alkenes via Free-Radical Multicomponent Cascade Reactions.

Based upon a radical polar effect, an intermolecular azidoheteroarylation of simple alkenes via a metal-free radical multicomponent cascade process was achieved. It allows a mild, rapid, and step-economic access to a broad range of azidoalkylated heteroaromatics. Given the diversity in transformations of organic azides and medicinally privileged scaffolds of heteroarenes, this strategy enables efficient synthesis and late-stage derivatization of drugs and candidates.