Tetrabutylammonium Iodide-Catalyzed Phosphorylation of Benzyl CH Bondsviaa Cross-Dehydrogenative Coupling (CDC) Reaction

Direct phosphorylation of benzylic C-H bonds under transition metal-free conditions forming sp3C-P bonds

Direct phosphorylation of benzylic C-H bonds was achieved in a biphasic system under transition metal-free conditions. A selective radical/radical sp3C-H/P(O)-H cross coupling was proposed, and various substituted toluenes were applicable. The transformation provided a promising method for constructing sp3C-P bonds.

The Synthesis and Mechanistic Considerations of a Series of Ammonium Monosubstituted H-Phosphonate Salts

A series of ammonium monosubstituted H-phosphonate salts were synthesized by combining H-phosphonate diesters with amines in the absence of solvent at 80 °C. Variation of the ester substituent and amine produced a range of ionic liquids with low melting points. The products and by-products were analyzed by spectroscopic and spectrometric techniques in order to get a better mechanistic picture of the dealkylation and formal dearylation observed. For dialkyl H-phosphonate diesters, (RO)₂ P(O)H (R=alkyl), the reaction proceeds via direct dealkylation with the reactivity increasing in the order R=iPr<Et<Me corresponding to DFT calculated activation enthalpies of 22.6, 20.8, and 17.9 kcal mol^-1 . For the diphenyl H-phosphonate diesters, (PhO)₂ P(O)H, the dearylation was found to proceed via phenol-assisted formation of a 5-coordinate intermediate, (PhO)₃ PH(OH), from which P(OPh)₃ and water were eliminated. The presence of an equivalent of water then facilitated the formation of P(OH)₂ OPh and the amine, R'NH₂ , subsequently abstracted a proton from it to yield [(PhO)PH(O)O]^- [R'NH₃ ]⁺ .

Metal-Free, N-Iodosuccinimide-Induced Regioselective Iodophosphoryloxylation of Alkenes with P(O)-OH Bonds

A simple and efficient method for the regioselective iodophosphoryloxylation of alkenes with P(O)-OH bonds has been established by using NIS (N-iodosuccinimide) as the iodination reagent under transition-metal-free conditions. The present protocol is compatible with different functional groups, and suitable for various alkenes and P(O)-OH compounds. A variety of functionalized β-iodo-1-ethyl phosphinic/phosphoric acid esters are obtained in good to excellent yields, which could be further transformed to diversified building blocks for the synthesis of bioactive compounds, pharmaceuticals and functional materials.

Cetyltrimethyl ammonium bromide catalysed oxidative cross dehydrogenative coupling of benzylic C(sp3)–H bonds in methylarenes with P(O)–OH compounds

A method for CTAB-catalysed oxidative cross dehydrogenative coupling of benzylic C(sp³)–H bonds in methylarenes with P(O)–OH compounds was reported.

Visible-light-mediated α-phosphorylation of N-aryl tertiary amines through the formation of electron-donor–acceptor complexes: synthetic and mechanistic studies

A visible light-mediated photocatalyst-free approach for the oxidative α-CH functionalization of N-aryl tertiary amines with secondary phosphine oxides has been developed.

DDQ-mediated direct C(sp3)–H phosphorylation of xanthene derivatives

A direct route to alkylphosphonates has been achievedviaDDQ-mediated cross-dehydrogenative coupling between diarylphosphine oxides and xanthene derivatives.

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.

Synthesis of benzyl esters from the commercially available alcohols catalyzed by TBAI via C(sp3)–H bond functionalization

The direct esterification of alcohol catalyzed by TBAI via C(sp³)–H bond functionalization was achieved under mild and clean conditions with good to excellent yields.

Azidation in the Difunctionalization of Olefins

Organic azides are key motifs in compounds of relevance to chemical biology, medicinal chemistry and materials science. In addition, they also serve as useful building blocks due to their remarkable reactivity. Therefore, the development of efficient protocols to synthesize these compounds is of great significance. This paper reviews the major applications and development of azidation in difunctionalization of olefins using azide reagents.

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.

Synthesis of 3-phosphinoylquinolines via a phosphinoylation–cyclization–aromatization process mediated by tert-butyl hydroperoxide

The first metal-free phosphinoylation–cyclization–aromatization method has been developed.

Cross-dehydrogenative coupling for the intermolecular C-O bond formation

The present review summarizes primary publications on the cross-dehydrogenative C-O coupling, with special emphasis on the studies published after 2000. The starting compound, which donates a carbon atom for the formation of a new C-O bond, is called the CH-reagent or the C-reagent, and the compound, an oxygen atom of which is involved in the new bond, is called the OH-reagent or the O-reagent. Alcohols and carboxylic acids are most commonly used as O-reagents; hydroxylamine derivatives, hydroperoxides, and sulfonic acids are employed less often. The cross-dehydrogenative C-O coupling reactions are carried out using different C-reagents, such as compounds containing directing functional groups (amide, heteroaromatic, oxime, and so on) and compounds with activated C-H bonds (aldehydes, alcohols, ketones, ethers, amines, amides, compounds containing the benzyl, allyl, or propargyl moiety). An analysis of the published data showed that the principles at the basis of a particular cross-dehydrogenative C-O coupling reaction are dictated mainly by the nature of the C-reagent. Hence, in the present review the data are classified according to the structures of C-reagents, and, in the second place, according to the type of oxidative systems. Besides the typical cross-dehydrogenative coupling reactions of CH- and OH-reagents, closely related C-H activation processes involving intermolecular C-O bond formation are discussed: acyloxylation reactions with ArI(O2CR)2 reagents and generation of O-reagents in situ from C-reagents (methylarenes, aldehydes, etc.).

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.

Mn(OAc)3-mediated phosphonation–lactonization of alkenoic acids: synthesis of phosphono-γ-butyrolactones

A new, general method for the synthesis of phosphono-γ-butyrolactones has been achieved through Mn(OAc)₃-mediated radical oxidative phosphonation and lactonization of alkenoic acids withH-phosphonates andH-phosphine oxide.

n-Bu4NI-catalyzed direct amination of ethers with aryl tetrazoles and triazoles via cross-dehydrogenative coupling reaction

An efficient, metal-free protocol for direct amination of ethers with aryl tetrazoles and triazoles has been developed using the TBAI/TBHP system.

Reusable ionic liquid-catalyzed oxidative coupling of azoles and benzylic compounds via sp3 C–N bond formation under metal-free conditions

The heterocyclic ionic liquid-catalyzed direct oxidative amination of benzylic sp³ C–H bonds via intermolecular sp³ C–N bond formation for the synthesis of N-alkylated azoles under metal-free conditions is reported for the first time.

Utilization of methylarenes as versatile building blocks in organic synthesis

This review attempts to describe the latest developments in the utilisation of methylarenes adopting C–H functionalization strategies and covers all the developments until March 2015.

Transition metal-free aroylation of NH-sulfoximines with methyl arenes

An iodine-catalyzed N-aroylation of NH-sulfoximines with methyl arenes was herein demonstrated without participation of external organic solvents, transition metal-catalysts or ligands.

A silver-initiated free-radical intermolecular hydrophosphinylation of unactivated alkenes

A scalable, operationally easy intermolecular hydrophosphinylation of various unactivated alkenes with H–P(O) compoundsviaan Ag(i)-initiated free radical process was developed. Mechanistic studies suggest that atom transfer processes were involved in this system.