Copper-Catalyzed Radical/Radical C sp 3H/PH Cross-Coupling: α-Phosphorylation of Aryl KetoneO-Acetyloximes

Stabilization of Two Radicals with One Metal: A Stepwise Coupling Model for Copper-Catalyzed Radical-Radical Cross-Coupling

Transition metal-catalyzed radical-radical cross-coupling reactions provide innovative methods for C-C and C-heteroatom bond construction. A theoretical study was performed to reveal the mechanism and selectivity of the copper-catalyzed C-N radical-radical cross-coupling reaction. The concerted coupling pathway, in which a C-N bond is formed through the direct nucleophilic addition of a carbon radical to the nitrogen atom of the Cu(II)-N species, is demonstrated to be kinetically unfavorable. The stepwise coupling pathway, which involves the combination of a carbon radical with a Cu(II)-N species before C-N bond formation, is shown to be probable. Both the Mulliken atomic spin density distribution and frontier molecular orbital analysis on the Cu(II)-N intermediate show that the Cu site is more reactive than that of N; thus, the carbon radical preferentially react with the metal center. The chemoselectivity of the cross-coupling is also explained by the differences in electron compatibility of the carbon radical, the nitrogen radical and the Cu(II)-N intermediate. The higher activation free energy for N-N radical-radical homo-coupling is attributed to the mismatch of Cu(II)-N species with the nitrogen radical because the electrophilicity for both is strong.

Visible-light promoted γ-cyanoalkyl radical generation: three-component cyanopropylation/etherification of unactivated alkenes

A photoredox approach to generate distal cyano-substituted alkyl radicals through C–C bond cleavage of cyclobutanone oximes was developed.

Visible-light-induced oxidative formylation of N-alkyl-N-(prop-2-yn-1-yl)anilines with molecular oxygen in the absence of an external photosensitizer

Visible-light-induced oxidative formylation of N-alkyl-N-(prop-2-yn-1-yl)anilines with molecular oxygen without an external photosensitizer was developed under mild reaction conditions.

Regiodivergent radical oxidative coupling of vinyl ethers with dithiane by copper or iron catalysis

Direct regioselective C–H dithioacetalization of readily available vinyl ethers to yield a variety of substituted dithianes under a copper or iron catalysis has been developed.

Coordination strategy-induced selective C–H amination of 8-aminoquinolines

Using coordination-strategy, we realized a selective C–H amination of 8-aminoquinolins on the C5 position employing azoles as amines sources.

Stereocontrolled C(sp3)–P bond formation with non-activated alkyl halides and tosylates

The current work provides a general approach for making C–P bonds with stereocontrol from chiral secondary alcohols.

Copper-catalyzed oxidative dehydrogenative coupling of carboxylic acids with H-phosphonates: an efficient and practical approach to acyl phosphate esters

A practical method through a copper-catalyzed dehydrogenative coupling of carboxylic acids with H-phosphonates to construct acyl phosphate esters has been developed.

t-BuOK-mediated reductive addition of P(O)–H compounds to terminal alkynes forming β-arylphosphine oxides

A novel and efficient t-BuOK-mediated reductive addition of P(O)–H compounds to terminal alkynes forming β-arylphosphine oxides was developed. This reaction may proceed via a tandem process involving regio-selective addition and subsequent transfer hydrogenation.

Synthesis of enaminones via copper-catalyzed decarboxylative coupling reaction under redox-neutral conditions

A novel copper-catalyzed C(sp³)–H oxidative functionalization of oxime acetates for the synthesis of enaminones under redox-neutral conditions has been developed.

Copper-catalyzed aerobic oxidative coupling of ketones with P(O)–H compounds leading to β-ketophosphine oxides

A facile copper-catalyzed one-pot method for the synthesis of β-ketophosphine oxides has been developed via aerobic oxidative coupling of ketones with P(O)–H compounds assisted by TBSOTf at room temperature.

Regioselective phosphinylation of coumarins under green LED irradiation and its mechanism

A regioselective and efficient approach to 3-phosphinylated coumarins was developed via the active P-centered radical generated by energy transfer and electron transfer processes under green LED irradiation.

Access to Thiazole via Copper-Catalyzed [3+1+1]-Type Condensation Reaction under Redox-Neutral Conditions

A new strategy for thiazoles via copper-catalyzed [3+1+1]-type condensation reaction from oximes, anhydrides and potassiumthiocyanate (KSCN) is developed herein. The transformation has good functional group tolerance and various thiazoles were formed smoothly in good to excellent yields under mild reaction conditions. This process involves copper-catalyzed N-O/C-S bond cleavages, activation of vinyl sp² C-H bond, and C-S/C-N bond formations which are under redox-neutral conditions as well as operational simplicity.

Visible-Light-Induced Cascade Reaction of Isocyanides and N-Arylacrylamides with Diphenylphosphine Oxide via Radical C-P and C-C Bond Formation

An effective photoredox-mediated tandem phosphorylation/cyclization reaction of diphenylphosphine oxide with three types of radical acceptors leads to P(O)Ph₂-containing phenanthridines, isoquinolines, and indolin-2-ones by formation of both C-P and C-C bonds. [Ir(ppy)₂(dtbpy)]PF₆ (1 mol %) was used as the catalyst, CsF or Cs₂CO₃ as the base, and K₂S₂O₈ as the oxidant. A series of functional groups can be tolerated at room temperature. Moderate to good yields were generated.

Iron-catalyzed synthesis of arylsulfinates through radical coupling reaction

A novel iron-catalyzed synthesis of arylsulfinates from diaryliodonium salts and rongalite through radical coupling reaction is described. Desired products can be prepared in good yields in air at room temperature in 20 minutes without the need for any ligands and additives.

Straightforward synthesis of functionalized chroman-4-ones through cascade radical cyclization-coupling of 2-(allyloxy)arylaldehydes

A novel and direct approach to synthesize a series of phosphonate, azide and hydroxy functionalized chroman-4-ones has been developed. The transformation appears to proceed via an intramolecular addition of in situ generated acyl radical onto alkene, followed by a radical/radical cross coupling.

Metal-free oxidative phosphinylation of aryl alkynes to β-ketophosphine oxides via visible-light photoredox catalysis

A visible-light-induced oxidative phosphinylation of arylacetylenes catalyzed by an inexpensive organic dye was demonstrated to be effective under mild conditions.

Silver-catalyzed synthesis of 2-arylvinylphosphonates by cross-coupling of β-nitrostyrenes with H-phosphites

An efficient protocol for stereoselective synthesis of vinylphosphonates has been developed via AgNO₃-catalyzed cross-coupling of β-nitrostyrenes with dialkyl H-phosphites under mild conditions.

A simple protocol for Cu-catalyzed protodecarboxylation of (hetero)aromatic carboxylic acids

A simple and practical protodecarboxylation of (hetero)aromatic carboxylic acids with various substituents through using CuI/Et₃N has been advantageously achieved.

Dehydrogenative coupling involving P(O)–H bonds: a powerful way for the preparation of phosphoryl compounds

This Frontier highlights the recent progress in the preparation of organophosphorus compounds via transition metal-catalysed dehydrogenative couplings of P(O)H compounds with Z–H compounds.

Dioxygen-induced oxidative activation of a P–H bond: radical oxyphosphorylation of alkenes and alkynes toward β-oxy phosphonates

The dioxygen-induced radical oxyphosphorylation of alkenes and alkynes is presented, wherein a P–H bond was activated by molecular oxygen.

Metal-free direct difunctionalization of alkenes with I2O5 and P(O)–H compounds leading to β-iodophosphates

A novel and efficient procedure for direct difunctionalization of alkenes with I₂O₅ and P(O)–H compounds has been developed under metal-free conditions.

Direct gem-difluoromethylenation of sp3-hybridized carbon center through copper-mediated radical/radical cross-coupling for the construction of a CH2–CF2 linkage

An efficient gem-difluoromethylenation of benzyl bromides through copper-mediated direct radical/radical C–C cross-coupling has been developed for the construction of CH₂–CF₂ linkage.

Stereoselective synthesis of vinylphosphonates and phosphine oxides via silver-catalyzed phosphorylation of styrenes

An efficient and stereoselective synthesis of vinylphosphonates and phosphine oxides was developed starting from styrenes using AgNO₃ as the catalyst and K₂S₂O₈ as the oxidant. Various vinyl-phosphonates and phosphine oxides were synthesized in good yields with excellent regioselectivity.