Regio- and stereoselective access to highly substituted vinylphosphine oxides via metal-free electrophilic phosphonoiodination of alkynes.

In general, the P-centered ring-opening of quaternary phosphirenium salts (QPrS) predominantly leads to hydrophosphorylated products, while the C-centered ring-opening is primarily confined to intramolecular nucleophilic reactions, resulting in the formation of phosphorus-containing cyclization products instead of difunctionalized products generated through intermolecular nucleophilic processes. Here, through the promotion of ring-opening of three-member rings by iodine anions and the quenching of electronegative carbon atoms by iodine cations, we successfully synthesize β-functionalized vinylphosphine oxides by the P-addition of QPrS intermediates generated in situ. Multiple β-iodo-substituted vinylphosphine oxides can be obtained with exceptional regio- and stereo-selectivity by reacting secondary phosphine oxides with unactivated alkynes.

Synthesis of alkenylphosphine oxides TfO promoted addition-elimination of ketones and secondary phosphine oxides.

Herein, we describe an efficient method for the synthesis of alkenylphosphine oxides a TfO promoted addition-elimination process. Various diarylphosphine oxides and alkylarylphosphine oxides react with ketones smoothly and produce alkenylphosphine oxides in moderate to excellent yields with abundant functional group compatibility. In addition, several transformations and applications of the product also demonstrate the potential value of the methodology.

Dual Photoredox/Nickel-Catalyzed Dehydrative Difluoroalkylation of Benzyl Alcohols for the Synthesis of Allylic -Difluorides.

A photoredox/Lewis acid cooperative catalytic system has been developed for the construction of C-C bonds through the dehydrative difluoroalkylation of benzyl alcohols. A variety of allylic -difluorides could be obtained in moderate yields with good to excellent / selectivity. In addition, several control experiments have been explored, and a possible mechanism was proposed for this process.

Copper-Catalyzed Asymmetric Cyanation of Propargylic Radicals via Direct Decarboxylation of Propargylic Carboxylic Acids.

Chiral propargylic cyanides are often used as small-molecule feedstocks for the introduction of chiral centers into various valuable products and complex molecules. Here, we have developed a highly atom-economical strategy for the chiral copper complex-catalyzed synthesis of chiral propargylic cyanides. Propargylic radicals can be smoothly obtained by direct decarboxylation of the propargylic carboxylic acids without preactivation.

Copper-Catalyzed 1,2-Dicarbonylative Cyclization of Alkenes with Alkyl Bromides via Radical Cascade Process.

Herein, we developed a new procedure on 1,2-dicarbonylative cyclization of 4-aryl-1-butenes with alkyl bromides. Using simple copper catalyst, two molecules of carbon monoxide were introduced into the double bond with the formation of four new C-C bonds and a new ring. Various α-tetralones and 2,3-dihydroquinolin-4-ones were formed in moderate to good yields.

Copper-Catalyzed Substrate-Controlled Carbonylative Synthesis of α-Keto Amides and Amides from Alkyl Halides.

Controllable production of α-keto amides and amides from the same substrates is an attractive goal in the field of transition-metal-catalyzed (double-)carbonylation. Herein, a novel copper-catalyzed highly selective double carbonylation of alkyl bromides has been developed. Moderate to good yields of α-keto amides were obtained as the only products.

Copper-catalyzed enantioselective carbonylation toward α-chiral secondary amides.

Secondary amides are omnipresent structural motifs in peptides, natural products, pharmaceuticals, and agrochemicals. The copper-catalyzed enantioselective hydroaminocarbonylation of alkenes described in this study provides a direct and practical approach for the construction of α-chiral secondary amides. An electrophilic amine transfer reagent possessing a 4-(dimethylamino)benzoate group was the key to the success.

NHC ligand-powered palladium-catalyzed carbonylative C-S bond cleavage of vinyl sulfides: efficient access to tert-butyl arylacrylates.

A method for palladium-catalyzed carbonylative C-S bond activation of divinyl sulfides to synthesize numerous tert-(E)-butyl arylacry-lates under 1 bar of CO has been developed. Employing electron-rich NHC as the ligand, the electron-rich and stabilized palladium complex trend to oxidative addition to the relatively inert C-S bond and decreased the poisoning effect of sulfide and CO; a series of tert-(E)-butyl acrylates were obtained in moderate to good yields.

Rhodium-Catalyzed Carbonylative Synthesis of Aryl Salicylates from Unactivated Phenols.

A rhodium-catalyzed carbonylative transformation of unactivated phenols to aryl salicylates is described. This protocol is characterized by utilizing 1,3-rhodium migration as the key step to provide direct access to synthesize -hydroxyaryl esters. Various desired aryl -hydroxybenzoates were produced in moderate to excellent yields with bis(dicyclohexylphosphino)ethane (DCPE) as the ligand.

Deaminative carbonylative coupling of alkylamines with styrenes under transition-metal-free conditions.

A transition-metal-free deaminative carbonylation of alkylamines with styrenes has been developed. The reaction shows good functional group compatibility and various α,β-unsaturated ketones were obtained in moderate to good yields. The alkyl radical generated from Katritzky salts via base-promoted C-N bond cleavage is one of the key intermediates in this reaction.

Nucleophilic Aromatic Substitution of Unactivated Aryl Fluorides with Primary Aliphatic Amines by Organic Photoredox Catalysis.

In this work, a mild and transition-metal-free approach for the nucleophilic aromatic substitution (S Ar) of unactivated fluoroarenes with primary aliphatic amines to form aromatic amines is reported. This reaction is facilitated by the formation of cationic fluoroarene radical intermediates in the presence of an acridinium-based organic photocatalyst under blue-light irradiation. Various electron-rich and electron-neutral fluoroarenes are competent electrophiles for this transformation.

Ruthenium-Catalyzed Carbonylative Coupling of Anilines with Organoboranes by the Cleavage of Neutral Aryl C-N Bond.

Herein, we report the first ruthenium-catalyzed Suzuki-type carbonylative reaction of electronically neutral anilines via C(aryl)-N bond cleavage. Without any ligand and base, diaryl ketones can be obtained in moderate to high yields by using Ru(CO) as the catalyst and chelation assisted by pyridine. The pyridine ring has a significant effect on both high efficiency and high regioselectivity in the cleavage of the aryl C-N bond in anilines.

Photocatalytic Hydrogen-Evolving Cross-Coupling of Arenes with Primary Amines.

Herein, we described a cooperative catalyst system consisting of an acridinium photoredox catalyst and a cobalt-based proton-reduction catalyst that is effective for the C-H amination of arenes with concomitant generation of hydrogen. This oxidant-free method allows a variety of amines with diverse functional groups to be converted to aromatic amines. Additionally, this protocol can also be extended to hydrolytically unstable benzophenone imines.

Mild dynamic kinetic resolution of amines by coupled visible-light photoredox and enzyme catalysis.

Herein, we described photoenzymatic dynamic kinetic resolution (DKR) of amines under mild conditions. The racemization of amines via a photoredox-mediated hydrogen atom transfer (HAT) protocol in conjunction with an enzyme catalyst to achieve the DKR of amines allows a variety of primary amines to be converted into a single enantiomer in high yield and with excellent enantioselectivity. Notably, this protocol can also be extended to 1,4-diamine derivatives with high levels of diastereo- and enantioselectivity.