Search

Enantioenriched unnatural amino acids represent a prevalent motif in organic chemistry, with profound applications in biochemistry, medicinal chemistry, and materials science. Herein, we report a cobalt-catalyzed aza-Barbier reaction of dehydroglycines with unactivated alkyl halides to afford unnatural α-amino esters with high enantioselectivity. This catalytic reductive alkylative addition protocol circumvents the use of moisture-, air-sensitive organometallic reagents, and stoichiometric chiral auxiliaries, enabling the conversion of a variety of primary, secondary, and even tertiary unactivated alkyl halides to α-alkyl-amino esters under mild conditions, thus leading to broad functional group tolerance. The expedient access to biologically active motifs demonstrates the practicality of this protocol by reducing the number of synthetic steps and enhancing the reaction efficiency.

The highly diastereoselective dicarbofunctionalization of substituted olefins still remains a daunting challenge in synthetic chemistry. Herein, we report a Pd-catalyzed diastereoselective 1,1-diarylation of 1,1-diarylethylene with chelation group free to enable the modular synthesis of smart material candidates, 1,1,2,2-tetraarylethanes (TAEs), which represent the first protocol by assembling four different aryl groups into ethane motif. Preliminary mechanistic experiments suggest that the crucial Pd-H species generated in situdo not disengage from the alkene intermediate during the reaction.

Transition metal nitrides have received considerable attention owing to their crucial roles in nitrogen fixation and nitrogen atom transfer reactions. Compared to the early and middle transition metals, it is much more challenging to access late transition metal nitrides, especially cobalt in group 9. So far, only a handful of cobalt nitrides have been reported; consequently, their hydrogenation reactivity is largely unexplored. Herein, we present a structurally and spectroscopically well-characterized thiolate-bridged dicobalt μ-nitride [Cp*CoIII(μ-SAd)(μ-N)CoIIICp*] (2) featuring a bent {CoIII(μ-N)CoIII} core. Remarkably, complex 2can realize not only direct hydrogenation of nitride to amide but also stepwise N–H bond formation from nitride to ammonia. Specifically, 2can facilely activate dihydrogen (H2) at mild conditions to generate a dicobalt μ-amide [Cp*CoII(μ-SAd)(μ-NH2)CoIICp*] (4) via an unusual mechanism of two-electron oxidation of H2as proposed by computational studies; in the presence of protons (H+) and electrons, nitride 2can convert to dicobalt μ-imide [Cp*CoIII(μ-SAd)(μ-NH)CoIIICp*][BPh4] (3[BPh4]) and to CoIICoIIμ-amide 4, and finally release ammonia. In contrast to 2, the only other structurally characterized dicobalt μ-nitride Na(THF)4{[(ketguan)CoIII(N3)]2(μ-N)} (ketguan = [(tBu2CN)C(NDipp)2]−, Dipp = 2,6-diisopropylphenyl) (e) that possesses a linear {CoIII(μ-N)CoIII} moiety cannot directly react with H2or H+. Further in-depth electronic structure analyses shed light on how the varying geometries of the {CoIII(μ-N)CoIII} moieties in 2and e, bent vs linear, impart their disparate reactivities.

A novel DMAP-catalyzed [4+3] spiroannulation of pyrazolone-derived Morita–Baylis–Hillman carbonates with N-(o-chloromethyl)aryl amides was developed. This reaction led to the assembly of medicinally relevant pyrazolone and azepine nuclei into a structurally new spirocyclic scaffold, and a diverse array of spiro[pyrazolone-azepine] products were afforded in good to excellent yields (up to 93%) with a wide substrate scope (23 examples) under mild conditions. Moreover, a gram-scale reaction and product transformations were conducted, which further increased the diversity of products.

Here we report a Pd-catalyzed isomerization of alicyclic allyl amine to achieve the unprecedented α,β-difunctionalization of synthetically inaccessible trisubstituted cyclic enamine. The dual role of in situformed enamine intermediate allows for the intermolecular formal [4 + 2] reaction with acrylamide or isatoic anhydride to simultaneously construct the C–C bond and C–N bond, thus realizing the expedient construction of [4.3.0]-aminal with excellent diastereoselectivity and high atom economy.

Unnatural chiral α-tertiary amino acids containing two different carbon-based substituents at the α-carbon centre are widespread in biologically active molecules. This sterically rigid scaffold is becoming a growing research interest in drug discovery. However, a robust protocol for chiral α-tertiary amino acid synthesis remains scarce due to the challenge of stereoselectively constructing sterically encumbered tetrasubstituted stereogenic carbon centres. Herein we report a cobalt-catalysed enantioselective aza-Barbier reaction of ketimines with various unactivated alkyl halides, including alkyl iodides, alkyl bromides and alkyl chlorides, enabling the formation of chiral α-tertiary amino esters with a high level of enantioselectivity and excellent functional group tolerance. Primary, secondary and tertiary organoelectrophiles are all tolerated in this asymmetric reductive addition protocol, which provides a complementary method for the well-exploited enantioselective nucleophilic addition with moisture- and air-sensitive organometallic reagents. Moreover, the three-component transformation of α-ketoester, amine and alkyl halide represents a formal asymmetric deoxygenative alkylamination of the carbonyl group.

Coordinatively unsaturated sulfur-supported iron complexes are conceived as suitable functional models for probing the potential biomimetic reactivity. In this regard, it is of continuous interest to construct this class of metallic complexes and investigate their unique properties for prospective applications. Here, we describe synthesis, characterization, and reactivity of a series of thiolate-bridged di- or multinuclear iron complexes supported by bulky 1,2,4-tri(tert-butyl)cyclopentadienyl (Cp′) ligands. Especially, detailed studies on variable-temperature solid-state magnetic susceptibility measurement and zero-field 57Fe Mössbauer spectroscopy at different temperatures reveal that the two iron centers in desirable [FeII(μ-SR)2FeII]-type complexes are all in intermediate- or high-spin configurations. Notably, when the substituent in the bridging thiolate ligand is the isopropyl group, the corresponding diiron complex exhibits temperature-induced reversible phase transition phenomenon. Its temperature-dependent magnetic susceptibility under successive cycles exhibits an 8 K wide hysteresis of magnetization caused by the reversible phase transition. Moreover, its single-crystal X-ray diffraction analyses at different temperatures clearly demonstrate the existence of phase transition accompanied by obvious thermal expansion upon heating, during which the corresponding space group varied from non-central tetragonal P4̅2(1)cbelow the inflection point temperature to central tetragonal P4(2)/mbcabove the inflection point temperature. In addition, these new iron complexes bearing sulfur donors are all proved to be good catalysts for the reductive silylation of N2.

Herein, we reported a Ni-catalyzed carbonylation of cyclopropanol with benzyl bromide to afford multisubstituted cyclopentenone under 1 atm of CO. The reaction proceeds through cascade carbonylation of benzyl bromides, followed by generation of nickel homoenolate from cyclopropanols via β-C elimination to afford 1,4-diketones, which undergoes intramolecular Aldol condensation to furnish highly substituted cyclopentenone derivatives in moderate to good yields. The reaction exhibits high functional group tolerance with broad substrate scope.

Thiolate-bridged hetero-bimetallic complexes [Cp*M(MeCN)N2S2FeCl][PF6] (2, M = Ru; 3, M = Co, Cp* =η5-C5Me5, N2S2 = N,N'-dimethyl-3,6-diazanonane-1,8-dithiolate) were prepared by self-assembly of dimer [N2S2Fe]2with mononuclear precursor [Cp*Ru(MeCN)3][PF6] or [Cp*Co(MeCN)3][PF6]2in the presence of CHCl3as a chloride donor. Complexes 2and 3exhibit obviously different redox behaviors investigated by cyclic voltammetry and spin density distributions supported by DFT calculations. Notably, iron-cobalt complex 3possesses versatile reactivities that cannot be achieved for complex 2. In the presence of CoCp2, complex 3can undergo one-electron reduction to generate a stable formally CoIIFeIIcomplex [Cp*CoN2S2FeCl] (4). Besides, the terminal chloride on the iron center in 3can be removed by dehalogenation agent AgPF6or exchanged with azide to afford the corresponding complexes [Cp*Co(MeCN)N2S2Fe(MeCN)][PF6]2(5) and [Cp*Co(MeCN)N2S2Fe(N3)][PF6] (6). In addition, complexes 2, 3and 4show distinct catalytic reactivity toward the disproportionation of hydrazine into ammonia. These results may be helpful to understand the vital role of the heterometal in some catalytic transformations promoted by heteromultinuclear complexes.

The activation of nitrosobenzene promoted by transition-metal complexes has gained considerable interest due to its significance for understanding biological processes and catalytic C–N bond formation processes. Despite intensive studies in the past decades, there are only limited cases where electron-rich metal centers were commonly employed to achieve the N–O or C–N bond cleavage of the coordinated nitrosobenzene. In this regard, it is significant and challenging to construct a suitable functional system for examining its unique reactivity toward reductive activation of nitrosoarene. Herein, we present a {Fe2S2} functional platform that can activate nitrosobenzene via an unprecedented iron-directed thiolate insertion into the N–O bond to selectively generate a well-defined diiron benzenesulfinamide complex. Furthermore, computational studies support a proposal that in this concerted four-electron reduction process of nitrosobenzene the iron center serves as an important electron shuttle. Notably, compared to the intact bridging nitrosoarene ligand, the benzenesulfinamide moiety has priority to convert into aniline in the presence of separate or combined protons and reductants, which may imply the formation of the sulfinamide species accelerates reduction process of nitrosoarene. The reaction pattern presented here represents a novel activation mode of nitrosobenzene realized by a thiolate-bridged diiron complex.

The first asymmetric trifluoromethylated allylic alkylation of pyrazolones using α-(trifluoromethyl)alkenyl acetates as a novel trifluoromethylated allylation reagent is described, affording various functionalized chiral pyrazolones containing a trifluoromethylated allyl substituent in high yields with excellent regio-/enantio-/diastereoselectivities. Mechanistically, the double-bond migration of α-(trifluoromethyl)alkenyl acetates in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene is initial and interesting step. More importantly, this study is of significance in providing a novel and widely applicable trifluoromethyl-containing allylation reagent.

Herein we report the nickel-catalyzed reductive dicarbofunctionalization of 1,1-disubstituted enamides with unactivated alkyl iodides to access the 3,3-dialkyl-substituted isoindolinone frameworks. This tandem cyclization/reductive coupling protocol exhibits broad functional group tolerance under mild conditions. The utilization of commercially accessible chiral Bn-Biox ligand allows excellent enantioselectivities to forge the tetrasubstituted stereocenters.

Using sterically demanding Cp′ (Cp′ = η5-1,2,4-tBu3C5H2) as auxiliary ligands, coordinatively unsaturated thiolate-bridged CrIICrIIcomplexes were obtained by a facile salt metathesis strategy. This dichromium system with vacant coordination sites can easily cleave the two carbon–halogen bonds of dihalomethane by a cooperative activation effect. Meanwhile, it can accommodate the resulting methylene moiety and two halide groups. Notably, an unprecedented thiolate-bridged CrIIICrIIImethylene complex was successfully isolated and unambiguously characterized by X-ray crystallography. Unlike the common chemical inertness of the {Cr–CH2–Cr} subunit, this bridging methylene fragment not only can interact with CH2Br2to give ethylene but can also transfer to styrene to generate the corresponding cyclopropanated product. In addition, the CrIIICrIIIcomplex containing two halides can be easily reduced by mild Zn powder to regenerate the initial CrIICrIIcomplex. Furthermore, this [Cr2S2] reaction scaffold can catalyze the cyclopropanation of styrenes using CH2Br2as the methylene source.

Iron nitrides are key intermediates in biological nitrogen fixation and the industrial Haber–Bosch process, used to form ammonia from dinitrogen. However, the proposed successive conversion of nitride to ammonia remains elusive. In this regard, the search for well-described multi-iron nitrido model complexes and investigations on controlling their reactivity towards ammonia formation have long been of great challenge and importance. Here we report a well-defined thiolate-bridged FeIVFeIVμ-nitrido complex featuring an uncommon bent Fe–N–Fe moiety. Remarkably, this complex shows excellent reactivity toward hydrogenation with H2at ambient conditions, forming ammonia in high yield. Combined experimental and computational studies demonstrate that a thiolate-bridged FeIIIFeIIIμ-amido complex is a key intermediate, which is generated through an unusual two-electron oxidation of H2. Moreover, ammonia production was also realized by treating this diiron μ-nitride with electrons and water as a proton source.

Herein, we disclose a nickel-catalyzed three-component reaction of internal enamide, diethoxymethylsilane, and aryl iodide to provide expedient access to benzylic amide derivatives. The protocol features a broad substrate scope with a moderate to excellent isolated yield under the mild condition. The high regioselectivity of Ni-catalyzed enamide hydroarylation can be attributed to the directing effect by the prefunctionalized nitrogen-containing group on the alkenes.

A general and practical approach to benzimidazothiazepine and benzimidazothioether derivatives via an intramolecular nucleophilic addition/ring expansion rearrangement of aryl isothiocyanates promoted by the tert-amino effect has been developed. This reaction is catalyzed by low-cost camphorsulfonic acid and tolerates a broad substrate scope with complete atom economy. Structurally intriguing benzimidazothiazepine and benzimidazothioether products could be easily obtained by a simple operation in good to excellent yield (up to 98%).

Herein, we report a nickel-catalyzed reductive cross-coupling reaction of easily accessible 3-butenyl carbamoyl chloride with primary alkyl iodide to access the chiral α-alkylated pyrrolidinone with broad substrate scope and high enantiomeric excess. The current art of synthesis still remains challenging on the enantioselective α-monoalkylation of pyrrolidinones. The newly designed chiral 8-quinoline imidazoline ligand (Quinim) is crucial for maintaining the reactivity and enantioselectivity to ensure the reductive cyclization of monosubstituted alkenes for unprecedented synthesis of chiral non-aromatic heterocycles.

Reported herein is a palladium-catalyzed secondary benzylic imidoylative Negishi reaction leveraging the sterically bulky aromatic isocyanides as the imine source. This method allows the facile access of alkyl-, (hetero)aryl-, and alkynylzinc reagents to afford various α-substituted phenylacetone products under mild acidic hydrolysis, which are ubiquitous motifs in many pharmaceuticals and biologically active compounds. The diastereoselective reduction of imine can be accomplished to provide the expedient conversion of secondary benzylic halide into α-substituted phenethylamine derivatives with high atom economy.

Reported herein is a palladium/copper cooperative-catalyzed dicarbofunctionalization of alkene-tethered carbamoyl chlorides with 1,1-diborylmethane. This cyclization/deborylation cascade strategy allows for the expedient formation of the versatile borylated 3,3-disubstituted oxindole skeleton, allowing for further functionalization via the derivatization of the carbon–boron bond.

Synthetic di- or multimetallic complexes bearing NxHynitrogenous ligands in a sulfur-rich coordination environment have attracted considerable attention due to their importance in evaluating the complex mechanism of biological nitrogen fixation. Herein, we report a series of thiolate-bridged dicobalt NxHyspecies obtained by treatment of CoIIICoIIIprecursor with hydrazine and its substituted derivatives at ambient temperature. Remarkably, when the substituent is the cyclohexyl group, the resulting species can interconvert through different pathways. This Co2S2skeleton provides a new model system for obtaining valuable information about the early N2Hx-bound intermediate species during the catalytic cycle of nitrogenase.

Phenylacetamides represent versatile feedstocks in synthetic chemistry, widely existing in drug molecules and natural products. Herein, we disclose a nickel-catalyzed formal aminocarbonylation of secondary benzyl chlorides with isocyanides yielding α-substituted phenylacetamide with steric hindrance, which is synthetically challenging via palladium-catalyzed aminocarbonylation. The reaction features wide functional group tolerance under mild conditions, highlighted by the tolerance of various aromatic halide (−Cl, −Br, −I) and heteroaromatic rings (pyridine and pyrazine).

We report herein a miscellaneous oxindole synthesis bearing an all-carbon quaternary center, enabled by Pd-catalyzed intramolecular cyclization followed by multiple intermolecular Heck reactions of both easily accessible alkene-tethered carbamoyl chlorides and olefins. This protocol obviates the use of prefunctionalized olefinic reagents, exhibits excellent functional group tolerance, and features fascinating reactive versatility.

Herein, we disclose a Ni-catalyzed formal aminocarbonylation of primary and secondary unactivated aliphatic iodides with isocyanides to afford alkyl amide, which proceeds via the selective monomigratory insertion of isocyanides with alkyl iodides, subsequent β-hydride elimination, and hydrolysis process. The reaction features wide functional group tolerance under mild conditions. Additionally, the selective, one-pot hydrolysis of reaction mixture under acid conditions allows for expedient synthesis of the corresponding alkyl carboxylic acid.

A “two-state reactivity” scenario has been computationally disclosed for dinitrogen activation by a diniobium tetrahydride. Remarkably, it is revealed that alkali metal cations play a crucial role via alkali···N coordination interaction, which is capable of decreasing the activation barriers of N–H formation and subsequent H2elimination in particular. Furthermore, the effect of various alkali metal cations has also been investigated systematically.

The development of a catalytic method for stereogenic carbon center formation holds immense significance in organic synthesis. Transition-metal-catalyzed cross-coupling reaction has been regarded as a straightforward and efficient tool for stereoselectively forging C–C bond. Nevertheless, the creation of acyclic all-carbon quaternary-containing vicinal stereocenters remains notoriously challenging within the domain of cross-coupling chemistry despite their prominence in various bioactive small molecules. Herein, we describe a palladium-catalyzed asymmetric multicomponent cross-coupling of trisubstituted alkene with aryl diazonium salts and arylboronic acids to realize the formation of tertiary-quaternary carbon centers with high regio-, distereo-, and enantioselectivity. Specifically, the precise manipulation of the stereoconfiguration of trisubstituted alkenes enables the divergent stereoselective cross-coupling reaction, thus allowing for the facile construction of all four enantiomers. Harnessing the ligand-swap strategy involving a chiral bisoxazoline and an achiral fumarate individually accelerates the enantioselective migratory insertion and reductive elimination step in the cross-coupling process, as supported by density functional theory (DFT) calculations, thus obviating the requirement for a neighboring directing group within the internal olefin skeleton.

We describe a nickel-catalyzed carbonylative cross-coupling of unactivated secondary alkyl electrophiles with the organozinc reagent at atmospheric CO gas, thus allowing the expedient construction of unsymmetric dialkyl ketones with broad functional group tolerance. The leverage of a newly developed NN2-pincer type ligand enables the chemoselective three-component carbonylation by overcoming the competing Negishi coupling, the undesired β-hydride elimination, and dehalogenation of alkyl iodides side pathways. Both alkyl iodides and alkyl tosylates are compatible in the single electron transfer involved mechanism.

The mechanisms of H–H and N–H bond cleavages of dihydrogen and ammonia mediated by the diiridium μ2-imido complex [(Cp*Ir)2(μ2-H)(μ2-NH)]+(A; Cp* = η5-C5Me5) were theoretically investigated with the density functional theory (DFT) method. Both oxidative addition and metal–ligand cooperation modes have been studied for H–H and N–H bond cleavages, respectively. The H–H bond cleavage most likely occurs through competitive oxidative addition and metal–ligand cooperation, and both cleavage modes have similar overall free energy barriers (24.3 and 25.7 kcal/mol, respectively). The ligand-assisted N–H bond heterolytic cleavage mechanism is proposed for the NH3reaction, and the general oxidative addition pathway can be reasonably ruled out, as it is kinetically unfavorable.

Nitrosobenzene (PhNO) and phenylhydroxylamine (PhNHOH) are of paramount importance because of their involvement as crucial intermediates in the biological metabolism and catalytic transformation of nitrobenzene (PhNO2) to aniline (PhNH2). However, a complete reductive transformation cycle of PhNO to PhNH2via the PhNHOH intermediate has not been reported yet. In this context, we design and construct a new thiolate-bridged dicobalt scaffold that can accomplish coordination activation and reductive transformation of PhNO. Notably, an unprecedented reversible ligand-based redox sequence PhNO0↔ PhNO•–↔ PhNO2–can be achieved on this well-defined {CoIII(μ-SPh)2CoIII} functional platform. Further detailed reactivity investigations demonstrate that the PhNO0and PhNO•–complexes cannot react with the usual hydrogen and hydride donors to afford the corresponding phenylhydroxylamino (PhNHO–) species. However, the double reduced PhNO2–complex can readily undergo N-protonation with an uncommon weak proton donor PhSH to selectively yield a stable dicobalt PhNHO–bridged complex with a high pKavalue of 13–16. Cyclic voltammetry shows that there are two successive reduction events at E1/2= −0.075 V and Ep= −1.08 V for the PhNO0complex, which allows us to determine both bond dissociation energy (BDEN–H) of 59–63 kcal·mol–1and thermodynamic hydricity (ΔGH–) of 71–75 kcal·mol–1of the PhNHO–complex. Both values indicate that the PhNO•–complex is not a potent hydrogen abstractor and the PhNO0complex is not an efficient hydride acceptor. In the presence of BH3as a combination of protons and electrons, facile N–O bond cleavage of the coordinated PhNHO–group can be realized to generate PhNH2and a dicobalt hydroxide-bridged complex. Overall, we present the first stepwise reductive sequence, PhNO0↔ PhNO•–↔ PhNO2–↔ PhNHO–→ PhNH2.

Biological nitrogen fixation mediated by nitrogenases has garnered significant research interest due to its critical importance to the development of efficient catalysts for mild ammonia synthesis. Although the active center of the most studied FeMo-nitrogenases has been determined to be a complicated [Fe7S9MoC] hetero-multinuclear metal–sulfur cluster known as the FeMo-cofactor, the exact binding site and reduction pathway of N2remain a subject of debate. Over the past decades, the majority of studies have focused on mononuclear molybdenum or iron centers as potential reaction sites. In stark contrast, cooperative activation of N2through bi- or multimetallic centers has been largely overlooked and underexplored, despite the renewed interest sparked by recent biochemical and computational studies. Consequently, constructing bioinspired bi- or multinuclear metallic model complexes presents an intriguing yet challenging prospect. In this Account, we detail our long-standing research on the design and synthesis of novel thiolate-bridged diiron complexes as nitrogenase models and their application to chemical simulations of potential biological N2reduction pathways.

Chiral-substituted 3-amino tetrahydro-2H-pyran-2-ones were prepared in excellent enantioselectivities (up to 99% ee) via an organo-catalyzed cascade procedure with N-TFA-Gly-Bt and α,β-unsaturated aldehydes as the substrates. The corresponding tetrahydro-2H-pyran-2-ones can be used for further synthetic transformations that furnish chiral-substituted 3-aminopiperidin-2-ones with high levels of stereoselectivity.

A direct transformation of aryl esters to secondary benzylic alcohols via tandem Ni-catalyzed cross-coupling reactions of aromatic 2-pyridyl esters with alkyl zinc reagents and carbonyl group reduction by Ni–H species is achieved. Preliminary mechanistic studies reveal that the Ni–H species is generated in situvia β-hydride elimination of the Negishi reagents. The reaction is catalyzed by bench-stable nickel salts under mild conditions with wide functional group tolerance.

Two types of zwitterionic polymer-modified magnetic nanoparticles (NPs) are fabricated by conjugating pSBMA onto PEI-precoated NPs via either a one-step method (1S NPs) or two-step method (2S NPs). For both methods, divinyl sulfone is used as the linker molecule. Although 1S NPs were capable of resisting both IgG and BSA, 2S NPs exhibited specificity toward IgG adsorption in complex biological fluids, e.g., in a mixture of serums and IgG. The moderate interactions (Kd≈ 1.2 μM) between IgG and 2S NPs are 3 orders of magnitude lower than IgG binding with protein A (Kd10 nM). Through complementary characterizations and analyses, we rationalize that the surface developed herein with IgG specificity contains two key components: polyzwitterions with a short chain length and sulfone groups with a high density.

A green and efficient approach to disulfides viaoxidative coupling of thiols was developed by adopting a biomimetic thiolate-bridged iron–ruthenium complex as the catalyst. Using environmentally friendly oxygen as the oxidant, a wide range of thiols including biologically important molecules can be smoothly converted into corresponding disulfides in water. Notably, two potential intermediate species were successfully isolated and unambiguously characterized, which is essential to reveal the detailed mechanism of this transformation. This catalytic system represents a rare and desired heteronuclear bimetallic scaffold for understanding the biological process of S–S bond formation from the viewpoint of bioinspired catalysis.

In the presence of 1 equiv of tBuNC, the homolytic cleavage of the FeIII–H bond in the diiron terminal hydride complex [Cp*Fe(t-H)(μ-η2:η4-bdt)FeCp*][BF4] (1[BF4]) smoothly took place to release 1/2 H2, followed by binding of a tBuNC group to the unsaturated FeIIcenter. Interestingly, upon exposure of 1[BF4]to 1 atm of acetylene, the isomerization process of the hydride ligand from the terminal to bridging coordination site was unaffected. Upon treatment of the diiron hydride bridged complex 2[BF4]with acetylene at 30 °C, two FeIII–H bonds were broken, and then an acetylene molecule was coordinated to the diiron centers in a novel μ-η2:η2side-on fashion. In the above reaction system, the hydride ligands whether terminal or bridging all play a role as the electron donor for the reduction of the diiron centers from FeIIIFeIIIto FeIIIFeII. These reaction patterns are reminiscent of the vital E4state responsible for N2binding and H2liberation in the catalytic cycle of nitrogenase, which contains two {Fe–H–Fe} motifs as electron reservoirs for the reduction of the iron centers. Differently, when treating 1[BF4]with TMSN3, the terminal hydride ligand was inserted into the azide group to give a diiron amide complex 4[BF4]in moderate yield.

The sulfur-based reactivity of transition-metal thiolate complexes toward alkenes has received extensive attention as a significant proposal for a potential olefin purification scheme. The one-electron oxidation of half-sandwich iron thioether-dithiolate complex [Cp*Fe(η3-tpdt)] (1, Cp* = η5-C5Me5; tpdt = S(CH2CH2S–)2) resulted in the formation of iron-stabilized thiyl radicals, which can interact with unsaturated hydrocarbons such as alkenes or alkynes to give the corresponding trithioether-iron adducts. Interestingly, during this transformation process, the formal oxidation state of the iron center changed from +IV to +II, which suggests a two-electron transfer from unsaturated hydrocarbons to the iron center. Furthermore, the electrochemical measurements reveal this C–S bond formation is an irreversible process, during which ethylene cannot release under electrochemical reductive conditions. These adducts were unambiguously identified by various spectroscopic and X-ray crystallographic characterizations.

A series of novel monothiolate-bridged dirhodium complexes, [Cp*Rh(μ-SR)(μ-Cl)2RhCp*][BF4] {Cp* = η5-C5Me5, R = tertiary butyl (tBu), 1a; R = ferrocenyl (Fc), 1b; R = adamantyl (Ad), 1c} were designed and successfully synthesized, which can smoothly facilitate highly regioselective and stereoselective hydrosilylation of terminal alkynes to afford β(Z) vinylsilanes with good functional group compatibility. Furthermore, the hydride bridged dirhodium complex [Cp*Rh(μ-StBu)(μ-Cl)(μ-H)RhCp*][BF4] (5) as a potential intermediate was obtained by the reaction of 1awith excess HSiEt3.

Several Ru-based catalysts were employed for the hydrogenation of levulinic acid and nanoporous Ru showed attractive catalytic performance for alcohols production. It was found that the total yield of 2-butanol and 2-pentanol was 78.8% and the yield of 1,4-pentadiol was 74.6%, respectively acquired at 140 °C and 100 °C using H2O as the solvent. Thanks to its acid site and lattice plane, nanoporous Ru provided sites for activating the lactone group of GVL and C–C/C–O bonds of PDO.

Treatment of complex [Cp*Fe(μ‐SEt)3FeCp*] (1; Cp* = pentamethylcyclopentadienyl) with isocyanides CNR affords the mononuclear complexes [Cp*FeSEt(CNR)2] (2a, R = tBu; 2b, R = Ph; 2c, R = Cy; 2d, R = Bn) in moderate yield. The heterobinuclear complexes [Cp*FeCNR(μ‐CNR)(μ‐SEt)PdCl(PPh3)][PF6] (3a, R = tBu; 3b, R = Ph; 3c, R = Cy; 3d, R = Bn), [Cp*Fe(CNtBu)2(μ‐SEt)NiCl(PPh3)][PF6] (4), and heterotrinuclear complexes [{Cp*Fe(CNtBu)2(μ‐SEt)}2M][PF6] (5, M = Au; 6, M = Ag; 7, M = Cu) have been prepared by the reaction of 2with complexes [PdCl2(PPh3)2], [NiCl2(PPh3)2], and [(Ph3P)M][X] (X = PF6or OTf, OTf = OSO2CF3), respectively. These complexes have been spectroscopically and crystallographically characterized.

Enantioselective transformations of olefins are among the most important strategies for the asymmetric synthesis of organic compounds. Chemo-, diastereo-, and stereoselective control of reactions with internal acyclic alkenes for the construction of functionalized acyclic alkanes still remain a persistent challenge. Here, we report a palladium-catalyzed asymmetric regiodivergent Heck-type diarylation of internal acyclic alkenes. The 1,2-diarylation of two accessible acyclic alkenes, cinnamyl carbamates and enamides with diazonium salts and aromatic boronic acids, furnishes products containing vicinal stereogenic centers via the stereospecific formation of carbonyl coordination-assisted transient palladacycles. Moreover, the asymmetric migratory diarylation of enamides enables the formation of incontiguous stereocenters by an interrupted diastereoselective 1,3-chain-walking process. This protocol streamlines access to highly functionalized multisubstituted enantioenriched carbamates and amine derivatives which are embedded in the key biologically active motifs.

Low-valence transition metallic complexes have drawn longstanding attention due to their high reactivity toward catalytic transformation of various small molecules. Among these known complexes, the low-valence metal centres are commonly stabilized by neutral bulky ligands with strong electron-donating capacity. However, low-valence bimetallic complexes supported by anionic sulfur and cyclopentadienyl ligands are still difficult to obtain in high isolated yield. Herein, we report the synthesis and characterization of two scarce thiolate-bridged CoICoIIand CoICoIcomplexes bearing sterically demanding ligands through two stepwise one-electron reduction processes. Interestingly, the CoICoIIcomplex can facilely promote the homolytic cleavage of dihydrogen across the short Co−Co metallic bond to give a CoIICoIIIdihydride bridged complex, which is capable of serving as a competent hydrogen atom transfer agent. Moreover, the anionic CoICoIcomplex can trigger a stepwise hydrogen generation cycle involving several isolated and structurally well-characterized intermediates.

A series of arylpyrazole (IV) and benzoxazinylpyrazole derivatives (IX) are synthesized and evaluated for their herbicidal activity.

Several novel 3‐arylisoxazole derivatives are synthesized based on the ring closure reaction of arylbutanediones (I) with hydroxylamine.

The catalyst generated promotes the asymmetric reaction of the diene (I) with aromatic and conjugated aldehydes to give functionalized esters of type (III) with excellent enantioselectivity.

Allylation reaction of primary and secondary amines as well as linear and cyclic active methylene compounds with allyl alcohol (II) is catalyzed by a novel catalyst‐cluster.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.