Search

Cooperative palladium-catalyzed and P(NEt2)3-mediated (4 + 1) annulations are developed, leading to a big library of spirooxindole derivatives in high structural diversity.

Both DFT calculations and experimental results revealed that the lone pair of the adjacent atom X facilitates the phosphirane fragmentation to form electrophilic phosphinidene complexes.

Tandem [5 + 1] carbonyl cyclization/[8 + 2] cycloaddition reactions of phosphiranes and tropones were developed as a straightforward method to access 6,5,7-fused tricyclic scaffolds.

Herein we report a diastereodivergent synthesis of fully disubstituted spiro[indoline-3,2′-pyrrolidin]-2-ones through base-promoted (3 + 2) cycloadditions. Importantly, the catalysts are found to have full control over the configuration of the stereocenters. When a Lewis base (PCy3) is used as a catalyst, good yields and excellent diastereoselectivities are obtained, regardless of the properties of the substituents, whereas spiro[indoline-3,2′-pyrrolidin]-2-ones of a different diastereoisomer are produced in good yields when a Bronsted base (K2CO3) is used. ESI-MS experiments proved the existence of key zwitterionic intermediates.

The phospha-Diels–Alder reaction between 2H-phospholes and arylallenes affords 6-methylene-1-phosphanorbornenes in high yields with excellent regioselectivity. This Diels–Alder reaction proceeds at the internal CC double bond of allenes selectively. DFT calculations of possible transition states finely demonstrate the regioselectivity of the reaction. The nucleophilic addition of Ph2PH to 6-methylene-1-phosphanorbornene sulfides and subsequent desulfurization provide the bidentate phosphine ligands 6, which have a fascinating 1-phosphanorbornene modified PCH2CH2P skeleton. The potential applications of 6 as ligands were demonstrated by coordination with transition metals.

The coordination chemistry of 1-phosphafulvenes was investigated by employing their [6 + 4] adducts or α-C2-bridged biphospholes as a precursor. Unbridged phosphacymantrenes arise from 1-phosphafulvenes via proton abstraction. α-C2-bridged biphosphacymantrenes are probably yielded by the reductive coupling of 1-phosphafulvene with Mn2(CO)10. The coordination behavior of 1-phosphafulvenes is comparable to that of pentafulvenes, which again demonstrates the phosphorus-carbon analogy in low-coordinate organophosphorus chemistry.

A copper-catalyzed asymmetric 1,3-dipolar cycloaddition of glycine iminoesters with alkyl substituted 3-methylene-2-oxindoles is described. By using de novo design of P-stereogenic phosphines as ligands, spiro[pyrrolidin-3,3'-oxindole]s are generated in good to excellent yields with high asymmetric induction. A further reduced catalyst loading of 0.1 mol% is sufficient to achieve a satisfactory enantioselectivity of 90% ee. The DFT calculations suggest the second Michael addition of the 1,3-dipole to be the rate- and enantio-determining step. A key feature of this 1,3-dipolar cycloaddition is the wide substrate applicability, even with alkyl aldehyde-derived azomethine ylide; thus it has streamlined a highly enantioselective access to a new class of antiproliferative agents, MDM2-p53.

A new family of phosphindole fused ladder-type heteroacenes with a pyrrolo[3,2-b]pyrrole core were synthesized and characterized, which show good luminescence efficiency, high thermostability and tunable conductance.

1-Iminylphosphirane W(CO)5 complexes react with alkenes under an atmosphere of CO at 130 °C to form the original 7-aza-1-phosphanorbornane complexes. The reaction works well with both electron-rich and electron-poor alkenes. On the basis of DFT calculations, we propose a mechanism including the rearrangement of phosphirane into a dipolar five-membered ring and the following cycloaddition of this dipolar intermediate with alkenes.

A phosphine catalyzed regiodivergent annulation of γ-substituted allenoates with conjugated dienes is reported, and highly functionalized cyclohexenes or cyclopentenes were obtained in high yields and regioselectivities. This transformation takes advantage of mild conditions, wide substrate scope and significant functional group tolerance. The high regioselectivity can be achieved by tuning the nucleophilicity of the phosphine catalyst.

Thermal rectification occurring at interfaces is an important research area, which contains deep fundamental physics and has extensive application prospects. In general, the measurement of interfacial thermal rectification is based on measuring interfacial thermal resistance (ITR). However, ITRs measured via conventional methods cannot avoid extra thermal resistance asymmetry due to the contact between the sample and the thermometer. In this study, we employed a non-contact infrared thermal imager to monitor the temperature of super-aligned carbon nanotube (CNT) films and obtain the ITRs between the CNT films and copper. The ITRs along the CNT-copper direction and the reverse direction are in the ranges of 2.2-3.6 cm2 K W-1 and 9.6-11.9 cm2 K W-1, respectively. The obvious difference in the ITRs of the two directions shows a significant thermal rectification effect, and the rectifying coefficient ranges between 0.57 and 0.68. The remarkable rectification factor is extremely promising for the manufacture of thermal transistors with a copper/CNT/copper structure and further thermal logic devices. Moreover, our method could be extended to other 2-dimensional materials, such as graphene and MoS2, for further explorations.

7-Phosphanorbornene sulfides were used as [RP = S] precursors. The reaction of these precursors with [M(PPh3)4] (M = Pd, Pt) yields star-like M4 clusters in which the central core is coated by three RP = S units acting as 4-electron μ2-P, η2-P = S ligands. The Pd cluster displays both stability and catalytic activity in the Suzuki–Miyaura reaction. DFT analysis suggests that a mononuclear [η2-RP = S]Pd(PPh3) complex is involved in the formation of the Pd4 clusters.

The available data on the activation of A-H sigma bonds by electrophilic terminal phosphinidene complexes are reviewed. Theoretical computations allow us to rationalize the experimental results. It appears that a successful insertion needs an initial interaction between the phosphinidene and the A-H bond, such as a donor-acceptor complex with a lone pair, a Coulombic interaction due to a negative charge on A or H, or a proximity effect.

The formation and migration energies of the mono-vacancies, foreign impurities (H, He and O atoms) and interstitials in Ti2AlN have been investigated using first principles calculations. The results have shown that the mono-vacancy formation is energetically most favorable for the Al atom. There are three stable configurations for the foreign impurities, the Al-layer triangle center site, the interstitial site (⅓,⅔,0.6578) and the vacancy site. It was also found that the O substitution is easily formed. For interstitials, the octahedral interstitial (Ti, N, H or O) and Al-layer triangle interstitial (Al or He) sites were observed in our simulation. Moreover, the H, O and N interstitials are dominant in Ti2AlN. These results could provide theoretical guidance for future experiments and for the application of Ti2AlN.

A multi-step synthesis of the title compound has been devised. In spite of its P=C double bond, the compound does not react at 100 °C with methanol and 2,3-dimethyl-1,3-butadiene. DFT calculations indicate a planar core, a long P=C double bond at 1.725 Å and a high-lying LUMO. Complexation can force the methoxy substituent to rotate out of the plane, thus restoring partly the double bond character of the P=C bond.

We present a molecular dynamic simulation on the mechanical strength and fracture behavior of graphene grain boundaries (GBs). The intrinsic strength, critical failure strain, and failure mechanism of graphene GBs mainly rely on the temperature and inflection angle, whereas the Young's modulus does not vary significantly with either temperature or boundary configuration. The overall intrinsic strengths of inflected GBs can be correlated with infection angle by a linear term, which is irrelevant to the system temperature. The initial failure sites of GBs locate either on the boundary line or inside the domain at high temperature.

Zirconaindenes reacted with allyl halides in the presence of ZnX2 (X = Cl or Br) and a catalytic amount of Pd(PPh3)4 to give naphthalene derivatives in good yield.