Search

A metal-free method for the dual activation of aryl phosphinate has been developed; the P–H and P–O bonds are sequentially activated by the Tf2O/DMSO system. Without the requirement of metals and unstable P-reagents, this one-pot procedure provides a convenient and practical access to a variety of aryl phosphonates. A mechanism involving twice generation of electrophilic P-species and two SN-processes is proposed on the basis of the control experiments. [ABSTRACT FROM AUTHOR]

Herein, metal-free phosphonation of N-heterocycles with diphenylphosphine oxides, promoted by easily available 1,5-diazabicyclo[5,4,0]undec-5-ene (DBU) in dimethyl carbonate (DMC) as a green solvent under an air atmosphere, is presented. This simple method can accommodate 1,2,4-triazine-3,5(2H,4H)-diones, quinoxalin-2(1H)-ones, quinoxalines and pyrazinones with diverse substituted diphenylphosphine oxides, delivering distinctive monophosphonated N-heterocycles with a broad functional group tolerance, and the transformations are also viable for post-modification of bioactive and pharmaceutical molecules. In addition to the sustainable feature of being metal- and photocatalyst-free and utilization of ambient air as an oxidant, this method efficiently achieves the gram-scale transformation, and the product was isolated through extraction and filtration, rather than column chromatography. [ABSTRACT FROM AUTHOR]

A novel strategy of bisphosphorylation of anhydrides with P(O)–H reagents via a DMAP-catalyzed and DBU-promoted process has been developed. These one-step transformations proceed efficiently to provide convenient access to a variety of P–O–C–P motif containing organophosphorus compounds. In addition, the gram-scale synthesis and the efficient recovery of the by-product highlight the sustainability and applicability of this method. [ABSTRACT FROM AUTHOR]

N-Phosphorylated amides continue to be an unparalleled asset for the development of pharmaceutical molecules, and the importance of this framework has inspired researchers to look for concise and efficient methods for the synthesis of this unit. In this work, a new strategy was developed in which a one-pot synthesis of N-phosphorylated amides was achieved by a three-component reaction with carboxylic acids, phosphorus chlorides and azides under mild reaction conditions. To our knowledge, this is the first study in which this framework was constructed through a multicomponent reaction, which is innovative, efficient and economical. [ABSTRACT FROM AUTHOR]

Visible-light-facilitated phosphorus radical reactions have been developed as a powerful and sustainable tool for the synthesis of various organophosphorus compounds. In general, these reactions require stoichiometric amounts of oxidants, and reductants, bases, and radical initiators, leading to uneconomical and complicated processes. Progress has been made over the past few years toward using reactions that proceed under eco-benign and mild reaction conditions. Furthermore, these reactions have broad functional group tolerance, with some facile and economical pathways. Herein, we summarize the discoveries and achievements pertaining to C–P bond formation through a visible light photocatalysis procedure with high atom economy, made by our group and other research groups. It was established that greener and more environmentally friendly approaches do not require an additional oxidant or base. Moreover, we have designed and synthesized a new type of P-radical precursor, which can take part in reactions without the requirement for any additional bases, oxidants, and additives. This breakthrough, pertaining to novel visible-light-induced transformations, will be discussed and a plausible mechanism is proposed, based on corresponding experiments and the literature. [ABSTRACT FROM AUTHOR]

A palladium-catalyzed, temporary P(O) directing group assisted C–H bond arylation of carbazoles was achieved. The release of the directing group occurs spontaneously in the reaction and the mechanistic studies indicate that acid is essential for N–P bond cleavage. [ABSTRACT FROM AUTHOR]

A novel type of oxime phosphonate was synthesized and used in the intermolecular cascade radical addition reaction of alkenes to access β-aminophosphonates via visible-light-driven N-centered iminyl radical-mediated and redox-neutral selective C–P single-bond cleavage in an active phosphorus radical route. The procedure is characterized by its ability to achieve the construction of Csp3–P and Csp3–N bonds without the requirement for oxidants and bases. [ABSTRACT FROM AUTHOR]

A Rh/Ni-catalyzed cascade sequence of allylamine isomerization and hydrophosphonylation to synthesize α-aminophosphonates has been disclosed. The reaction, which not only allows the generation of widespread valuable α-aminophosphonates under simple systems and mild conditions, but also enriches the process of olefin isomerization–addition both in catalytic systems and various reaction types. [ABSTRACT FROM AUTHOR]

The first Cu-catalyzed cascade sp3 C–H bond oxidative functionalization of the 2-ethylazaarenes has been developed. The two different sp3 C–H bonds in 2-ethylazaarenes are selectively oxidized and four new types of bonds (C=O, C=N, C–C, C–O) are constructed in one operation. Starting from the simple substrates and cheap nitro source, this reaction provides an efficient approach to produce new kinds of isoxazolines. [ABSTRACT FROM AUTHOR]

A novel and convenient approach to the synthesis of various phosphorated indolines via a copper-catalyzed radical cascade cyclization reaction has been developed. The reaction employs cheap copper as the catalyst and K2S2O8 as the oxidant under mild conditions. Various alkenes and P-radical precursors are compatible with this transformation. Preliminary mechanistic studies reveal that the addition of the P-radical may initiate the reaction, and then oxidative cyclization may be achieved to afford the desired product. [ABSTRACT FROM AUTHOR]

A novel metal-free oxidative carbonitration of alkenes by a nitration and C–H functionalization cascade process has been developed. This methodology provides an efficient way to construct valuable nitro-containing oxindoles. [ABSTRACT FROM AUTHOR]

A novel protocol for the preparation of various 3-alkylideneoxindoles viaa silver-catalyzed aromatic C–H functionalization has been developed. The process is simple, environmentally conscious, and avoids the use of abundant bases, oxidants, or other additives. [ABSTRACT FROM AUTHOR]

An oxidative homo dimerization of N-protected and free indole derivatives toward bioactive 3,3′-linked biindolyl scaffolds viaPd-catalyzed direct C–H transformations was first successfully demonstrated. [ABSTRACT FROM AUTHOR]

A novel metal-free oxidative carbonitration of alkenes by a nitration and C–H functionalization cascade process has been developed. This methodology provides an efficient way to construct valuable nitro-containing oxindoles. [ABSTRACT FROM AUTHOR]

A metal-free method for the dual activation of aryl phosphinate has been developed; the P-H and P-O bonds are sequentially activated by the Tf 2 O/DMSO system. Without the requirement of metals and unstable P-reagents, this one-pot procedure provides a convenient and practical access to a variety of aryl phosphonates. A mechanism involving twice generation of electrophilic P-species and two S N -processes is proposed on the basis of the control experiments.

Visible-light-facilitated phosphorus radical reactions have been developed as a powerful and sustainable tool for the synthesis of various organophosphorus compounds. In general, these reactions require stoichiometric amounts of oxidants, and reductants, bases, and radical initiators, leading to uneconomical and complicated processes. Progress has been made over the past few years toward using reactions that proceed under eco-benign and mild reaction conditions. Furthermore, these reactions have broad functional group tolerance, with some facile and economical pathways. Herein, we summarize the discoveries and achievements pertaining to C-P bond formation through a visible light photocatalysis procedure with high atom economy, made by our group and other research groups. It was established that greener and more environmentally friendly approaches do not require an additional oxidant or base. Moreover, we have designed and synthesized a new type of P-radical precursor, which can take part in reactions without the requirement for any additional bases, oxidants, and additives. This breakthrough, pertaining to novel visible-light-induced transformations, will be discussed and a plausible mechanism is proposed, based on corresponding experiments and the literature.

A palladium-catalyzed, temporary P(O) directing group assisted C-H bond arylation of carbazoles was achieved. The release of the directing group occurs spontaneously in the reaction and the mechanistic studies indicate that acid is essential for N-P bond cleavage.

The first Cu-catalyzed cascade sp(3) C-H bond oxidative functionalization of the 2-ethylazaarenes has been developed. The two different sp(3) C-H bonds in 2-ethylazaarenes are selectively oxidized and four new types of bonds (C=O, C=N, C-C, C-O) are constructed in one operation. Starting from the simple substrates and cheap nitro source, this reaction provides an efficient approach to produce new kinds of isoxazolines.

A new method for the synthesis of chiral α-amino acid derivatives by enantioselective C-H arylation of N-aryl glycine esters with aryl boric acids in the presence of a chiral Pd(II)-catalyst has been developed. This work successfully integrates the direct C-H oxidation with asymmetric arylation and exhibits excellent enantioselectivity.

An efficient method for the synthesis of phosphoric fluoride via oxidative coupling between hydrophosphine oxide and NaF is reported. DDQ serves as the oxidizing reagent as well as the hydrogen acceptor. The process involves a Cu(II) catalysis and exhibits great functional group tolerance under mild reaction conditions.

The first Cu(i)-catalyzed cross-coupling reaction by hydrogen (H2) removal for the stereoselective synthesis of 3-phosphoindoles is reported. Going beyond the oxidative dehydrogenative coupling reactions reported recently, this reaction completely omits the oxidant and base, producing hydrogen (H2) as the only byproduct.

A novel and efficient Pd-catalyzed C-H acetoxylation is described. The approach uses R2(O)P as a directing group to synthesize various substituted 2'-phosphorylbiphenyl-2-OAc compounds. Notably, the reaction exhibits smooth operation under mild conditions and shows good functional group tolerance. Products are obtained with high selectivity and yields.

Palladium-catalyzed arylation of (diisopropylphosphoryl)biphenyl skeleton derivatives by the P(O)R2 directed C-H functionalization was reported. The related products were obtained in high regioselectivity and good functional group tolerance was observed. This reaction provided a new and efficient pathway for the synthesis of polyaromatic monophosphorus ligands.

A novel metal-free oxidative carbonitration of alkenes by a nitration and C-H functionalization cascade process has been developed. This methodology provides an efficient way to construct valuable nitro-containing oxindoles.

A novel protocol for the preparation of various diarylphosphine oxide compounds via a Ni-catalyzed cross-coupling of aryl chlorides with R(2)P(O)H has been developed. Notably, this process exhibits the following very attractive features: (i) the process is simpler and operates under mild reaction conditions; (ii) the process is generally cheaper in part because the more accessible aryl chloride is used to form the C-P bond; (iii) the process avoids the need for simultaneous preparation and use of Ar(2)P(O)M.

A novel protocol for the preparation of various 3-alkylideneoxindoles via a silver-catalyzed aromatic C-H functionalization has been developed. The process is simple, environmentally conscious, and avoids the use of abundant bases, oxidants, or other additives., (This journal is © The Royal Society of Chemistry 2011)

An oxidative homo dimerization of N-protected and free indole derivatives toward bioactive 3,3-linked biindolyl scaffolds via Pd-catalyzed direct C-H transformations was first successfully demonstrated.