Interface Engineering in Two‐Dimensional Heterostructures: Towards an Advanced Catalyst for Ullmann Couplings

The design of advanced catalysts for organic reactions is of profound significance. During such processes, electrophilicity and nucleophilicity play vital roles in the activation of chemical bonds and ultimately speed up organic reactions. Herein, we demonstrate a new way to regulate the electro‐ and nucleophilicity of catalysts for organic transformations. Interface engineering in two‐dimensional heteronanostructures triggered electron transfer across the interface. The catalyst was thus rendered more electropositive, which led to superior performance in Ullmann reactions. In the presence of the engineered 2D Cu₂S/MoS₂ heteronanostructure, the coupling of iodobenzene and para‐chlorophenol gave the desired product in 92 % yield under mild conditions (100 °C). Furthermore, the catalyst exhibited excellent stability as well as high recyclability with a yield of 89 % after five cycles. We propose that interface engineering could be widely employed for the development of new catalysts for organic reactions.     

Stereoselective Synthesis of Functionalized Pyrrolidines by the Diverted N−H Insertion Reaction of Metallocarbenes with β‐Aminoketone Derivatives

A highly stereoselective route to functionalized pyrrolidines by the metal‐catalyzed diverted N?H insertion of a range of diazocarbonyl compounds with β‐aminoketone derivatives is described. A number of catalysts (rhodium(II) carboxylate dimers, copper(I) triflate, and an iron(III) porphyrin) are shown to promote the process under mild conditions to give a wide range of highly substituted proline derivatives. The reaction starts as a metallocarbene N?H insertion but is diverted by an intermolecular aldol reaction.     

Electronic properties of polyoxometalate derivatives [(C2B9H11) M'M5O18]n‐ (M' = TiIV,MoVI, WVI; M = MoVI,WVI): Protonation,Electronic Spectra,and Redox Properties

Density functional theory is used to study the electronic structures and properties of Lindqvist‐type polyoxometalates‐supported organometallic compounds [LM'M₅O₁₈]^n– (L = [C₂B₉H₁₁]^2– (Cb), [C₅H₅]^– (Cp); M' = Ti^IV, Mo^VI, W^VI; M = Mo^VI, W^VI). [(Cb)M'M₅O₁₈]^n– are a series of novel compounds designed in this work, based on related experiment. The calculated results reveal that the Cb ligand is able to form a σ, 2π triple bond with M', which is similar to the bond character in [(Cp)M'M₅O₁₈]^n–. However, comparing with the protonation, electronic spectra and redox properties of [(Cp)M'M₅O₁₈]^n– and [M'M₅O₁₉]^n–, [(Cb)M'M₅O₁₈]^n– species show the advantageous electronic properties owning to the superior electron donating ability of the Cb ligand. © 2015 Wiley Periodicals, Inc.     

A New Class of Amide Ligands Enable Cu‐Catalyzed Coupling of Sodium Methanesulfinate with (Hetero)aryl Chlorides

((2S ,4R )‐4‐Hydroxy‐N ‐(2‐methylnaphthalen‐1‐yl)pyrrolidine‐2‐carboxamide (HMNPC), an amide derived from 4‐hydroxy‐L ‐proline and 2‐methyl naphthalen‐1‐amine, is a powerful ligand for Cu‐catalyzed coupling of (hetero)aryl halides with sulfinic acid salts, allowing for first time the metal‐catalyzed coupling of (hetero)aryl chlorides and NaSO₂Me. A considerable number of (hetero)aryl chlorides worked well, providing the pharmaceutically important (hetero)aryl methylsulfones in good to excellent yields.     

Aqueous microwave-assisted DMAP catalyzed synthesis of β-phosphonomalonates and 2-amino-4H-chromen-4-ylphosphonates via a domino Knoevenagel-phospha-Michael reaction

An aqueous microwave (mw)-assisted DMAP catalyzed one-pot highly efficient route to synthesize β-phosphonomalonates and 2-amino-4H-chromen-4-yl phosphonates has been demonstrated via the domino Knoevenagel-phospha-Michael reaction of aryl aldehyde/salicylaldehyde, malononitrile/ethyl cyanoacetate and alkyl phosphite ester. Optimization of reaction conditions were performed by using conventional and microwave synthetic approaches. This conversion proceeded smoothly to deliver the desired product in good to excellent yields (75–95%) in a short reaction time (10–12 min). The present methodology is very simple, environmentally benign, high yielding and has very well demonstrated the synergistic effect of water and microwaves.     

Cationic Polymerization: From Photoinitiation to Photocontrol

During the last 40 years, researchers investigating photoinitiated cationic polymerizations have delivered tremendous success in both industrial and academic settings. A myriad of photoinitiating systems have been developed, thus allowing polymerization of a broad array of monomers (e.g., epoxides, vinyl ethers, alkenes, cyclic ethers, and lactones) under practical, inexpensive, and environmentally benign conditions. More recently, owing to progress in photoredox catalysis, photocontrolled cationic polymerization has emerged as a means to precisely regulate polymer chain growth. This Minireview provides a concise historical perspective on cationic polymerization induced by light and discusses the latest advances in both photoinitiated and photocontrolled processes. The latter are exciting new directions for the field that will likely impact industries ranging from micropatterning to the synthesis of complex biomaterials and sequence‐controlled polymers.     

A stereoselective synthesis of the C(3)-C(13) and C(14)-C(24) fragments of macrolactin A

Synthetic studies towards(he C(3)-C(13)and C(14)-C(24)segments(3,4)of the potent antiviral and antitumor compound macrolactin A(1)are presented.Compound 3 was constructed via a convergent and facile approach,exploiting Wittig olefination to generate the sensitive E,Z-diene moiety.Compound 4 was synthesized from the chiral-pod derived sul-fone 39a via an o-alkylation-desulfonation reaction sequence.Cu(Ⅱ)-catalyzed coupling of a Grignard reagent with an al-lylic bromide and Julia olefination were also investigated for the preparation of compound 4.     

不饱和类卡宾H_2C=CLiF的结构及氢迁移反应的DFT研究

用量子化学中的密度泛函DFT方法,在B3LYP/6-311G~*水平上研究了不饱和类 卡宾H_2C=CLiF的结构。结果表明,只有1种平衡结构是稳定的。对稳定的平衡结构 ,找到了分子内氢迁移反应的过渡态,并计算了不同温度下不饱和类卡宾 H_2C=CLiF的平均寿命τ,在200 K时,τ = 7.9 d,在300 K仅为τ = 2.4 s。     

Borylation of saturated heterocycles with several heteroatoms. (Review)

New examples of the borylation of a series of five-and six-membered saturated 1,3-and 1,3,2-heterocycles with the formation of cyclic boric esters are described. The probable mechanism of the reaction is discussed. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 643–654, May, 2006.     

DFT Study on Intermolecular Cleavage Reaction of N-（2-Hydroxyphenyl）-phthalamic Acid

The reaction mechanisms of intermolecular cleavage reaction of N-（2-hydroxyphenyl）-phthalamic acid were studied via the density functional theory（DFT）. All geometries of the reactant, transition states, and products were optimized at the B3LYP/6-31G（d, p） level. Vibration analysis was carried out to confirm its identity as transitions＇ structure, and the intrinsic reaction coordinate method（IRC） was used to search the minimum energy path. Two possible reaction channels are reported in this article. The calculated results indicate that O-cyclization reaction channel has the lower activation barrier, and therefore, it occurs more easier than the other.