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Phosphenium ions [R

A divergent intramolecular phosphination of alkynes is developed. Fine tuning of chemo- and regioselectivity has been realized by just adding LiBr or H

Herein, we report a facile and highly atom-economic approach to 2-phosphafurans by using simple 2-chloroethylphosphine and acetylenic ketones. The key step of this protocol utilizes the Lewis acidity of electrophilic phosphinidenes to induce an intramolecular cyclization with enones. Dearomative hetero-Diels-Alder reactions of 2-phosphafurans provide two series of bicyclic phosphacycles. This rare synthetic application of Lewis acidity of electrophilic phosphinidene complexes represents a new frontier of phosphinidene chemistry.

Three series new NH2-benzophosphole oxides were synthesized from cycloaddition of o-aminophenyl phosphine oxide with alkynes. Photophysics investigation and theoretical calculation indicate that the position of amino group in these benzophosphole oxides obviously regulate their properties. 4-NH2-benzo[b]phosphole oxides show strong fluorescence emission and high fluorescence quantum efficiency. This “One stone three birds” process provides rapid access to multiple organophosphorus based luminogens for the structure–property relationship study.

Herein we reported a novel phosphine-catalyzed (4 + 2) cyclization reaction of electron-deficient conjugated dienes with enones to generate functionalized dihydropyran skeletons. A mechanistic investigation reveals that the reaction produces a new phosphonium zwitterion, which undergoes consecutive reactions. In addition, an asymmetric variant was developed by efficient and economical chiral phosphine catalysis.

We have developed an unprecedented approach for the synthesis of transient 1-phosphafulvenes through three component reactions of phospholes. The generation of 1-phosphafulvenes was demonstrated by in situ [6 + 4] cycloaddition with 2H-phospholes and [6 + 6] self-dimerization. The [6 + 4] and [6 + 6] reaction pathway could be modulated by the starting ketones and aldehydes. The construction of 1-phosphafulvenes is illustrated by a proposed mechanism combining nucleophilic addition of phospholide to the iminium or isomerized azomethine ylide and a [1,5]-shift of phosphole.

In this report, a series of biphosphirane complexes 1 were synthesized from the phosphiranide complex. The binuclear Mn2(CO)10-catalyzed intramolecular dimerization of these biphosphirane complexes...

[1 + 2] cycloaddition is a classical reaction between the electrophilic phosphinidene and an alkene. However, a spatial constraint blocks this well-known reaction and enables an unprecedented chemoselective C(sp2)-Ar σ-bond insertion of the alkene. The theoretical calculations demonstrate that this C-C bond cleavage is energetically feasible and thermodynamically favored through an electrophilic rearrangement and concomitant 1,9-aryl migration without involving any strained intermediate.

An unusual chemoselective 1,1-addition of α-C2-bridged biphospholes to terminal alkynes is reported. The developed protocol provides simple access to the unknown 1,3-diphosphepines, which has poten...

A simple method to build phospholene derivatives has been achieved in a one-pot reaction with readily available o-alkynylaryl bromides and alkylphosphine oxides. This method is also applicable to s...

A short and efficient route to peri-fused heterocycles has been developed. The transition metal in cooperation with the imino directing group cleaves the C-P bond of the phosphirane, followed by 1,1-insertion of CO and reductive elimination to give a reactive azaphosphacyclohexone derivative. The further dearomatic Diels-Alder reaction of the in situ-generated azaphosphacyclohexone with alkenes provides an array of annulated heterodecalins with high molecular complexity and atomic utilization.

A novel (4 + 3) annulation reaction of Morita–Baylis–Hillman carbonates and vinyl benzoxazinanones has been developed by using phosphine/palladium dual catalysis. This reaction demonstrates a wide substrate scope, providing a range of vinyl 2, 3-dihydro-1H-benzo[b]azepine derivatives in moderate to good yields and diastereoselectivities. Experimental results indicate that both palladium and phosphine play crucial roles in the annulation reactions.

A Ag/P-stereogenic phosphine-complex-catalyzed 1,3-dipolar cycloaddition of azomethine ylides with electron-deficient olefins is reported. In this reaction, highly functionalized pyrrolines with a spiro-quaternary stereogenic center were obtained in good yields (up to 99%) with excellent levels of diastereo- (up to >20:1 dr) and enantioselectivities (up to >99% ee). The chirality of adducts was controlled predominantly by the P-stereogenic phosphines.

A new pair of P-stereogenic ligands with multiple chiral centers were synthesized and used in the copper(I)-catalyzed enatioselective [3 + 2] cycloaddition of iminoesters with alkenes. A variety of highly functionalized pyrrolidines were obtained in excellent yield and enatioselectivity. This is the first example of a pair of P-stereogenic ligands working as pseudoenantiomers to tune the enantio- and diastereoselective 1,3-dipolar cycloaddition, and providing a pair of enantiomerically pure pyrrolidines, respectively.

Carbon nanotubes (CNTs) and other related CNT-based materials with a high thermal conductivity can be used as promising heat dissipation materials. Meanwhile, the miniaturization and high functionality of portable electronics, such as laptops and mobile phones, are achieved at the cost of overheating the high power-density components. The heat removal for hot spots occurring in a relatively narrow space requires simple and effective cooling methods. Here, an auxiliary passive cooling approach by the aid of a flat plate (aluminum-magnesium alloy) is investigated to accommodate heat dissipation in a narrow space. The cooling efficiency can be raised to 43.5%. The cooling performance of several CNT-based samples is compared under such circumstances. Heat dissipation analyses show that, when there is a nearby plate for cooling assistance, the heat radiation is weakened and natural convection is largely improved. Thus, improving heat radiation by increasing emissivity without reducing natural convection can effectively enhance the cooling performance. Moreover, the decoration of an auxiliary cooling plate with sprayed CNTs can further improve the cooling performance of the entire setup.

The unprecedented 2,2'-bis(azaphosphindole) has been synthesized via a new route. Reaction with NaH afforded a dianion derivative 5, which is easily transformed to alkylated bis(azaphosphindole) or (Z)-P,P,N,N-cisoid diazadiphosphafulvalene. The reaction features good regioselectivity and high steroselectivity. Relatively strong fluorescence is observed with diazadiphosphafulvalenes. The X-ray crystal structure analysis showed that dianion ligand 5 is bonded to two Na atoms in a bridging cis-fashion, which allows the synthesis of diazadiphosphafulvalene in a highly stereoselective approach.

A polycyclic imidazolophosphinine has been synthesized by collapse of the bridge of an appropriate 7-phosphanorbornene. This stable compound has been characterized by X-ray crystal structure analysis. It is fully planar with a P═C bond length of 1.733(4) A. The lone pair at P is poorly reactive and corresponds to HOMO–3. The compound reacts with a protic acid and methyl iodide at the sp2 nitrogen and with AuCl with the α-methoxy substituent, yielding a zwitterionicacylphosphidewhose complexation at P gives a bis-gold complex. Both the protonated product and the bis-gold complex have been characterized by X-ray crystal structure analysis.

A facile method to synthesize quaternized benzophospholes on gram scale was reported, and the products were isolated by simple filtration. During this research, a series of σ5-oxaphosphoranes incorporating polycyclic aromatic hydrocarbons (PAHs) were obtained. The grafting of α-phenolate groups on the phosphorus center enhances the coplanarity of the system.

Electrophilic terminal phosphinidene complexes [R1P-W(CO)5] bearing 2-alkynylphenyl R1 substituents undergo a spontaneous cyclization to give intermediate five-membered species which are able to perform an electrophilic substitution reaction with toluene and mesitylene. An intramolecular version of this reaction is possible with appropriate R substituents on the C≡C triple bond.

The title phosphine-isocyanides were obtained by reaction of 2-lithioaryl isocyanides with diarylchlorophosphines. They cyclize to 1,3-benzazaphospholes with cleavage of their two aryl–P bonds upon treatment with an excess of lithium in THF. Their P═CH2 ylids spontaneously evolve to give λ5-1,4-benzazaphosphinines. Their complexation by gold(I), palladium(II), and nickel(II) chlorides has been investigated. An original pincer diphosphine–carbene complex has been obtained with palladium. The new products have been characterized by X-ray crystal structure analysis.

1-Phosphafulvenes can be easily generated by dissociation of dimers resulting from the reaction of phospholes with aldimines. As electron-rich partners, they act as 4π phosphadienic systems toward alkenes and alkynes in [4 + 2] cycloaddition reactions. As electron-poor partners, they act either as 2π systems toward conjugated dienes in [2 + 4] cycloaddition reactions via their P═C double bond or as 6π systems toward phosphadienes in [6 + 4] cycloaddition reactions.

Under Pd(II)/CuI cocatalysis, o-diarylphosphinophenylalkynes cyclize in boiling toluene via C-P bond cleavage and arylphosphination of the C≡C bond. This protocol provides an unprecedented atom- and step-efficient access to optoelectronically and biologically interesting benzophospholes.

Phospholides are easily obtained by treatment of the open-chain acetylenic phosphines shown by an excess of lithium at room temperature in THF (12 examples).

Transient terminal phosphinidene complexes [RP-W(CO)5] dimerize in the presence of copper chloride, and the dimers react in situ with triphenylphosphine–borane to give the disecondary diphosphine complexes [RPH–PHR][W(CO)5]2. When R = CH2CH2Cl, a cyclization takes place to give the diphosphirane complex. A 1,2-diphospholane is obtained for R = Ph by further reaction with 1,3-dibromopropane in the presence of aqueous K2CO3.

The reaction of a phosphole-2,5-diol with a tripyrromethane in the presence of BF3 generates, after oxidation by DDQ, a P-confused carbaporphyrinoid whose X-ray crystal structure analysis has been performed. The steric bulk of the phosphorus subunit prevents the formation of the expected phosphaporphyrin.

In contrast with an earlier report, the reaction of 1-phenyl-3,4-dimethylphosphole with an excess of dimethyl acetylenedicarboxylate (DMAD) at room temperature affords the phosphole + 2 DMAD ylide 10, whose structure was established by a careful analysis of the 13C NMR spectrum. Its stability is surprising, since the analogous Ph3P + 2 DMAD adduct spontaneously rearranges to other products and has never been fully characterized. When the reaction of phosphole with DMAD was carried out in the presence of AgNO3, the intermediate 1:1 adduct was oxidized to the stable oxo-ylide 13, whose X-ray crystal structure shows the highly zwitterionic character.

The hydrolysis of a phosphanorbornenium triflate gives the expected tertiary phosphine oxide by cleavage of one P-C bond of the bridge in the presence of triethylamine but affords the secondary phosphine oxide by cleavage of the two P-C bonds of the bridge in the presence of alpha-picoline.