96-48-0

γ-Butyrolactone was produced highly selectively from biomass-derived 1,4-butanediol by vapor-phase dehydrocyclization over novel copper-silica nanocomposite catalyst. Compared with usual Cu(12)/SiO2, the highly Cu-loaded SiO2 nanocomposite (80 wt%) exhibited high catalyst performance with 98% yield on 400 h stream without significant deactivation even in the absence of H2.

In this paper, Au/TiO2 nanocomposite was synthesized and utilized as highly efficient and green photocatalyst for organic reactions. A sheet-like anatase titanium dioxide material with a highly active (001) crystal plane was prepared via a solvothermal method. Gold nanoparticles were then loaded on the surface of TiO2 by a liquid-phase reduction method to give an Au/TiO2 material with good photocatalytic activity. The Au/TiO2 nanocomposite was utilized as a photocatalyst to develop a light-promoted Minisci oxidative coupling reaction of ether and aza aromatics by using oxygen as green oxidant and only catalytic amount of acid as additive. The protocol shows a good functional group tolerance as well as good to excellent yields for various substrates. With mechanistic studies, Au/TiO2 nanocomposite proved to be an efficient photocatalyst to activate C?H bond via a SEO approach of heteroatoms. Moreover, the solid semiconductor photocatalyst shows good recycling performance, could be easily recovered and reused without significant decrease in yield.

Spiropyrans bearing an N-alkylcarboxylate tether are a common structure in dynamic, photoactive materials and serve as colourimetric/fluorimetric cation receptors. In this study, we describe an efficient synthesis of spiropyrans with 2–12 carbon atom alkylcarboxylate substituents, and a systematic analysis of their interactions with metal cations using 1H NMR and UV-visible spectroscopy. All N-alkylcarboxyspiropyrans in this study displayed a strong preference for binding divalent metal cations and a modest increase in M2+ binding affinity correlated with increased alkycarboxylate tether length.

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The reactions of alkylperoxyl radicals with phenols have remained difficult to investigate in water. We describe herein a simple and reliable method based on the inhibited autoxidation of water/THF mixtures, which we calibrated against pulse radiolysis. With this method we measured the rate constants kinh for the reactions of 2-tetrahydrofuranylperoxyl radicals with reference compounds: urate, ascorbate, ferrocenes, 2,2,5,7,8-pentamethyl-6-chromanol, Trolox, 6-hydroxy-2,5,7,8-tetramethylchroman-2-acetic acid, 2,6-di-tert-butyl-4-methoxyphenol, 4-methoxyphenol, catechol and 3,5-di-tert-butylcatechol. The role of pH was investigated: the value of kinh for Trolox and 4-methoxyphenol increased 11- and 50-fold from pH 2.1 to 12, respectively, which indicate the occurrence of a SPLET-like mechanism. H(D) kinetic isotope effects combined with pH and solvent effects suggest that different types of proton-coupled electron transfer (PCET) mechanisms are involved in water: less electron-rich phenols react at low pH by concerted electron-proton transfer (EPT) to the peroxyl radical, whereas more electron-rich phenols and phenoxide anions react by multi-site EPT in which water acts as proton relay. Radical kinetics: A simple and reliable method to measure the kinetics of peroxyl radical reactions in water is described (see figure). The proton-coupled electron transfer from a variety of compounds was investigated. Electron-poorer phenols react by concerted electron-proton transfer (EPT or CPET), whereas electron-richer phenols and phenoxide anions react by multi-site EPT (separated CPET) in which water acts as proton relay, similarly to the chemistry of radical enzymes.

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In this study, a novel, strategic method was developed for the synthesis of a mesoporous silica catalyst embedded with ruthenium nanoparticles (RuNPs/SiO2) by combining the polyol and modified sol-gel methods. By applying this new procedure, uniformly synthesized ruthenium nanoparticles with an average size of 3.8 nm and 95% spherical shape were highly dispersed in the mesoporous silica support material. Coordinated carbonyl groups of PVP remaining from the synthesis of the RuNPs were effectively removed by the thermal treatment (calcined at 573 K for 4 h) and the sythesized RuNPs/SiO2 catalysts were reduced under hydrogen at 20 bar for 2 h. These catalysts were analyzed using transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), N2 adsorption-desorption, and X-ray diffraction (XRD). After the thermal treatment and the reduction procedure, the size and shape of the embedded RuNPs were nearly unchanged, and the catalyst was active in the liquid-phase hydrogenation of succinic anhydride (SAN) to selectively form γ-butyrolactone (GBL) with a maximum yield of 90.1%. This novel catalyst preparation is a potentially useful method for the synthesis of metal nanoparticles as heterogeneous catalysts. Copyright

With the aim of applying redox-neutral cascade reactions in organic media, fusions of a type II flavin-containing monooxygenase (FMO-E) and horse liver alcohol dehydrogenase (HLADH) were designed. The enzyme orientation and expression vector were found to influence the overall fusion enzyme activity. The resulting bifunctional enzyme retained the catalytic properties of both individual enzymes. The lyophilized cell-free extract containing the bifunctional enzyme was applied for the convergent cascade reaction consisting of cyclobutanone and butane-1,4-diol in different microaqueous media with only 5 % (v/v) aqueous buffer without any addition of external cofactor. Methyl tert-butyl ether and cyclopentyl methyl ether were found to be the best organic media for the synthesis of γ-butyrolactone, resulting in about 27 % analytical yield.

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The isomerization of 2-butyne-1,4-diol to butyrolactone catalysed by ruthenium complexes is described.

Primary N-C adducts of γ-aminobutyric acid (GABA) to acylacetylenes undergo mild stereoselective C-vinylation by another acylacetylene molecule to afford (2E,4Z)-4-acyl-5-aminoalka-2,4-dien-1-one-type diadducts in 83-92% yields. The latter cyclize to acyl

Au/TiO2 catalysts prepared by the deposition-precipitation method showed excellent activity and selectivity in the oxidative cyclization of 1,4-butanediol to γ-butyrolactone, with high yields (>99%) under mild conditions (413 K, 1.25 MPa air). Catalysts with 3-8% gold loading and calcined at 573-673 K were all highly active for the formation of γ-butyrolactone, as demonstrated by XRD, TEM, XPS, ICP and UV-vis DRS results. It is concluded that highly dispersed small (2-10 nm) gold particles are formed with the surface enrichment of gold. The ratio of cationic gold to metallic gold depends on the treatment temperature. These findings, combined with those of the activity tests, lead to the conclusion that the surface metallic nanosized gold particles are active sites. The catalyst can be reused with no drop in activity or selectivity.

γ-Valerolactone can be synthesized by reduction of levulinic acid and its esters in the presence of secondary alcohols as hydrogen donors and Ru/C as catalyst. The reaction rate increases when using microwave heating. Quantitative formation of γ-valerolactone was observed within 25 min at 160 °C under microwave heating based on levulinic acid and i-propanol. The reaction appears to proceed via a dehydrogenation-hydrogenation sequence.

Cu-CeO2-Al2O3 catalysts were prepared by the co-precipitation method with different washing operations during the preparation process for the purpose of controlling the contents of the residual sodium and water in the catalyst precursors. Cu-CeO2-Al2O3 catalysts were characterized by ICP-AES, XRD, SEM, nitrogen sorption, N2O chemisorption, Raman spectroscopy and H2-TPR. Effects of the residual sodium and water in the catalyst precursor on the catalytic performance of Cu-CeO2-Al2O3 catalyst for gas-phase hydrogenation of maleic anhydride to γ-butyrolactone at atmospheric pressure, and the structure-activity relationships were investigated. The results show that the residual water and sodium in the form of Na2CO3 in the catalyst precursor lead to a decrease in Cu dispersion and Cu surface area, which is disadvantageous to the catalytic performance and stability. Washing step of the residual sodium in the catalyst precursor with the deionized water and then removing step of the residual water using azeotropy distillation shows a great improvement in the stability of Cu-CeO2-Al2O3 catalyst, in which 100% of conversion of maleic anhydride and 100% of selectivity to γ-butyrolactone were maintained for 12 h.

Selenium-doped TiO2 has been used for the first time as efficient photocatalyst for the oxidation of tetrahydrofuran by using hydrogen peroxide as oxidant, affording γ-butyrolactone (GBL) in excellent yield with higher selectivity. TiO2-doped with selenium showed greater visible absorption and exhibited superior photocatalytic activity than undoped TiO2. The prepared catalyst was subjected to reflux in Millipore water in order to remove the surface-bound selenium species. After this treatment, the catalyst did not show any leaching and showed efficient recycling with consistent catalytic efficiency. Georg Thieme Verlag Stuttgart · New York.

Optically active δ- and γ-lactones are obtained by the homogeneous catalytic dehydrogenation of prochiral diols using Ru2Cl4((-)-DIOP)3 in the presence of benzalacetone as a hydrogen acceptor and triethylamine.

Heterogeneous palladium catalysts with high atom-efficiency offer practical value for selective hydrogenation. Here, we prepared atomically dispersed Pd species supported on γ-AlOOH nanosheets (Pd/γ-AlOOH), which contain clusters and dominated single atoms. Even with an extremely low amount of Pd loading, the catalytic activity of 0.1Pd/γ-AlOOH leads to 50.3% of succinic acid conversion at 4 h. At the time, the succinic acid conversion reaches 90.7% and 97.1%, and the selectivity to γ-butyrolactone is high up to 96.9% and 93.8% over 0.5Pd/γ-AlOOH and 1.0Pd/γ-AlOOH, respectively. The supported Pd single atom (Pd1/γ-AlOOH) Exhibits 30- and 1100-fold increase in the catalytic activity compared with the supported clusters Pd13/γ-AlOOH and Pd55/γ-AlOOH for the selective hydrogenation of succinic acid to γ-butyrolactone, respectively. Analysis of the structural properties confirms that Pd single atoms on γ-AlOOH (0 1 0) surface have high adsorption energy, which is in agreement with catalytic efficiency. In addition, Pd single atoms in the catalyst 0.2Pd/γ-AlOOH account for 86.6% of the overall catalytic activity and can serve as the most efficient catalytic active sites.

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Acid catalysed hydrolyses of spiroorthoeters (1, 2a, 2b, and 2c and spirocarbonates (3 and 4) were carried out to give the corresponding ring-opening reaction products.The ring-cleavage modes of these spiro derivatives depended on the structure of intermediate cations.

The efficient hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) over a hydrotalcite-derived non-precious metal Co/Al2O3 catalyst was achieved. Its core-shell structure and a strong interaction between Co and Al species stabilized the Co particles against leaching and sintering. This magnetic non-precious metal catalyst showed a comparable catalytic performance to a commercial Ru/C for the liquid hydrogenation of LA. It was easily separated from the reaction medium with an external magnet. The catalyst exhibited excellent recyclability, complete LA conversion and >99% GVL selectivity, and would be useful in a large scale biorefinery.

A coupling process of the hydrogenation of maleic anhydride and the dehydrogenation of 1,4-butanediol has been invented for the synthesis of γ-butyrolactone over a Cu-Zn catalyst, realizing optimal hydrogen utilization and better energy efficiency.

The two-stage hydrogenation of maleic anhydride (MAH) in the liquid phase yielded γ-butyrolactone (GBL). The first stage was the hydrogenation of MAH to succinic anhydride (SAH) and the second stage was the subsequent hydrogenation of SAH to GBL which was studied using a homogeneous catalyst. In the hydrogenation of SAH, a novel ruthenium catalyst system composed of Ru(acac)3, P(octyl)3, and p-toluenesulfonic acid (p-TsOH) was developed exhibiting excellent catalytic performance, with > 95% selectivity for GBL and higher activity than that reported in the literature. p-TsOH was significant in enhancing the reaction rate and improving selectivity. A structural change in the Ru complexes was induced by p-TsOH resulting in the cationic exchange which showed higher catalyst activity. It also prevented the undesired side reaction catalyzed by free P(octyl)3, resulting in high selectivity for GBL. The process which yielded GBL features the external preparation method of the Ru complex, the coupling reaction, and the separation to remove water (a product of hydrogenation of SAH) to increase the reaction rate. To recover > 90% of the catalyst, a catalyst recovery system was developed.

Cyclobutanones were selectively oxidized to yield γ-butyrolactones with hydrogen peroxide in 2,2,2-trifluoroethanol.

A series of methacrylates bearing bicyclobis(γ-butyrolactone) (BBL) moiety were synthesized and radically polymerized to afford the corresponding poly(methacrylate)s bearing BBL moiety in the side chain, with expecting that the high polarity and rigidity of BBL would be inherited by the polymers. The resulting polymers were soluble in polar aprotic solvents such as dimethyl sulfoxide and N,N-dimethylformamide because of the high polarity of the BBL moiety. The glass transition temperatures (Tg) of the polymers depended on the length of methylene linker that tethered the methacrylate and BBL moieties, making the use of shorter linkers lead to higher Tgs.

The assembly of heterometallic complexes capable of activating dioxygen is synthetically challenging. Here, we report two different approaches for the preparation of heterometallic superoxide complexes [PhL2CrIII-η1-O2][MX]2 (PhL = -OPh2SiOSiPh2O-, MX+ = [CoCl]+, [ZnBr]+, [ZnCl]+) starting from the CrII precursor complex [PhL2CrII]Li2(THF)4. The first strategy proceeds via the exchange of Li+ by [MX]+ through the addition of MX2 to [PhL2CrII]Li2(THF)4 before the reaction with dioxygen, whereas in the second approach a salt metathesis reaction is undertaken after O2 activation by adding MX2 to [PhL2CrIII-η1-O2]Li2(THF)4. The first strategy is not applicable in the case of redox-active metal ions, such as Fe2+ or Co2+, as it leads to the oxidation of the central chromium ion, as exemplified with the isolation of [PhL2CrIIICl][CoCl]2(THF)3. However, it provided access to the hetero-bimetallic complexes [PhL2CrIII-η1-O2][MX]2 ([MX]+ = [ZnBr]+, [ZnCl]+) with redox-inactive flanking metals incorporated. The second strategy can be applied not only for redox-inactive but also for redox-active metal ions and led to the formation of chromium(III) superoxide complexes [PhL2CrIII-η1-O2][MX]2 (MX+ = [ZnCl]+, [ZnBr]+, [CoCl]+). The results of stability and reactivity studies (employing TEMPO-H and phenols as substrates) as well as a comparison with the alkali metal series (M+ = Li+, Na+, K+) confirmed that although the stability is dependent on the Lewis acidity of the counterions M and the number of solvent molecules coordinated to those, the reactivity is strongly dependent on the accessibility of the superoxide moiety. Consequently, replacement of Li+ by XZn+ in the superoxides leads to more stable complexes, which at the same time behave more reactive toward O-H groups. Hence, the approaches presented here broaden the scope of accessible heterometallic O2 activating compounds and provide the basis for further tuning of the reactivity of [RL2CrIII-η1-O2]M2 complexes.

This study examined a hydrogen transfer reaction from 1,4-butanediol to nitrobenzene for γ-butyrolactone and aniline simultaneously over Cu-CoOx-MgO catalysts. The catalyst was developed by co-precipitation followed by metal hydroxycarbonate mixing and calcination at three different temperatures (500, 700, and 900 °C). The hydrogenation of nitrobenzene to aniline and the dehydrogenation of 1,4-butanediol to γ-butyrolactone was accomplished in a gas-phase fixed-bed continuous reactor system at 250 °C. The catalyst Cu-CoOx-MgO-500 calcined at 500 °C showed outstanding performance because of the higher copper dispersion and negligible spinel species (CuCo2O4 /MgCo2O4) compared to the other two catalysts. The order of activity decreased with increasing calcination temperature from 500° to 900°C. The activity trend followed the order, Cu-CoOx-MgO-500 > Cu-CoOx-MgO-700 > Cu-CoOx-MgO-900. The effect of calcination on the catalytic properties was analyzed by atomic absorption spectroscopy elemental analysis, Brunauer-Emmett-Teller surface area, N2O pulse chemisorption, temperature-programmed reduction-H2, X-ray diffraction, and X-ray photoelectron spectroscopy. The results showed that Cu-CoO-MgO-500 exhibited more active copper sites (Cu0/Cu+1) and optimal metal-support interactions that decrease the reduction temperature of copper. On the other hand, Cu-Co and Mg-Co spinel (CuCo2O4/MgCo2O4) content, which adversely affects the catalyst activity, increased with increasing calcination temperature. In summary, simultaneous hydrogenation and dehydrogenation reactions via hydrogen transfer reactions have potential commercial applications.

Catalytic selective hydrogenation of esterified malic acid to produce 1,2,4-butanetriol (1,2,4-BT) using H2 as the reducing reagent suffers from the low 1,2,4-BT selectivity. Here, Ru/SiO2 catalyst was employed for selective hydrogenation of dimethyl malate (DM) to produce 1,2,4-BT, which gave abnormal high DM conversion (100%) and 1,2,4-BT selectivity (92.4%) in aqueous solvent at 363?K, especially, the 1,2,4-BT yield even is higher than the optimal catalyst reported (Ru-Re, 79.8%). The reaction pathways for the DM hydrogenation on Ru/SiO2 were also proposed, suggesting that extremely high 1,2,4-BT selectivity require for the much high hydrogenation rates at low temperatures, where side-reaction transesterification rates are relatively low. The extremely high hydrogenation activity and 1,2,4-BT selectivity on Ru/SiO2 in aqueous solvent at low temperatures arise from that H2O may coordinate to Ru2+ and prevent the reduction of Ru2+ to Ru under high H2 pressure. Ru/SiO2 surface presents abundant Ru2+ in aqueous solvent, can activate H2 through heterolytic cleavage mode to form hydride, which can significantly increase hydrogenation rates of C = O groups at low temperatures. In addition, the activity and 1,2,4-BT selectivity on Ru/SiO2 catalyst only reduced by 2.3% and 2.6%, respectively over a period of 550?h. Graphical Abstract: [Figure not available: see fulltext.]

We report the dehydrogenative synthesis of esters from enol ethers using water as the formal oxidant, catalyzed by a newly developed ruthenium acridine-based PNP(Ph)-type complex. Mechanistic experiments and density functional theory (DFT) studies suggest that an inner-sphere stepwise coupled reaction pathway is operational instead of a more intuitive outer-sphere tandem hydration-dehydrogenation pathway.

Here, we disclose a new copper(i)-Schiff base complex series for selective oxidation of primary alcohols to aldehydes under benign conditions. The catalytic protocol involves 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO), N-methylimidazole (NMI), ambient air, acetonitrile, and room temperature. This system provides a straightforward and rapid pathway to a series of Schiff bases, particularly, the copper(i) complexes bearing the substituted (furan-2-yl)imine bases N-(4-fluorophenyl)-1-(furan-2-yl)methanimine (L2) and N-(2-fluoro-4-nitrophenyl)-1-(furan-2-yl)methanimine (L4) have shown excellent yields. Both benzylic and aliphatic alcohols were converted to aldehydes selectively with 99% yield (in 1-2 h) and 96% yield (in 16 h). The mechanistic studies via kinetic analysis of all components demonstrate that the ligand type plays a key role in reaction rate. The basicity of the ligand increases the electron density of the metal center, which leads to higher oxidation reactivity. The Hammett plot shows that the key step does not involve H-abstraction. Additionally, a generalized additive model (GAM, including random effect) showed that it was possible to correlate reaction composition with catalytic activity, ligand structure, and substrate behavior. This can be developed in the form of a predictive model bearing in mind numerous reactions to be performed or in order to produce a massive data-set of this type of oxidation reaction. The predictive model will act as a useful tool towards understanding the key steps in catalytic oxidation through dimensional optimization while reducing the screening of statistically poor active catalysis.

An amide/iminium zwitterion catalyst has a catalyst pocket size that promotes transesterification and dehydrative esterification. The amide/iminium zwitterions are easily prepared by reacting aziridines with aminopyridines. The reaction can be applied a wide variety of esterification processes including the large-scale synthesis of biodiesel. The amide/iminium zwitterions allow the avoidance of strongly basic or acidic condition and avoidance of metal contamination in the products. Reactions are carried out at ambient or only modestly elevated temperatures. The amide/iminium zwitterion catalyst is easily recycled and reactions proceed in high to quantitative yields.

In this study,in situformed ruthenium hydride species that were generated from Grubbs type catalysts are used as efficient catalysts for dehydrogenative alcohol coupling and sequential cross-metathesis/dehydrogenative coupling reactions. The selectivity of Grubbs first generation catalysts (G1) in dehydrogenative alcohol coupling reactions can be tuned for the ester formation in the presence of weak bases, while the selectivity can be switched to the β-alkylated alcohol formation using strong bases. The performance of Hoveyda-Grubbs 2nd generation catalyst (HG2) was improved in the presence of tricyclohexylphosphine for the selective synthesis of ester derivatives with weak and strong bases in quantitative yields. Allyl alcohol was used as self and cross-metathesis substrate for the HG2 catalyzed sequential cross-metathesis/dehydrogenative alcohol coupling reactions to obtain γ-butyrolactone and long-chain ester derivatives in quantitative yields.

A Cp*Ir(III) complex (1) of a newly designed ligand L1 featuring a proton-responsive pyridyl(benzamide) appended on N-heterocyclic carbene (NHC) has been synthesized. The molecular structure of 1 reveals a dearomatized form of the ligand. The protonation of 1 with HBF4 in tetrahydrofuran gives the corresponding aromatized complex [Cp*Ir(L1H)Cl]BF4 (2). Both compounds are characterized spectroscopically and by X-ray crystallography. The protonation of 1 with acid is examined by 1H NMR and UV-vis spectra. The proton-responsive character of 1 is exploited for catalyzing α-alkylation of ketones and β-alkylation of secondary alcohols using primary alcohols as alkylating agents through hydrogen-borrowing methodology. Compound 1 is an effective catalyst for these reactions and exhibits a superior activity in comparison to a structurally similar iridium complex [Cp*Ir(L2)Cl]PF6 (3) lacking a proton-responsive pendant amide moiety. The catalytic alkylation is characterized by a wide substrate scope, low catalyst and base loadings, and a short reaction time. The catalytic efficacy of 1 is also demonstrated for the syntheses of quinoline and lactone derivatives via acceptorless dehydrogenation, and selective alkylation of two steroids, pregnenolone and testosterone. Detailed mechanistic investigations and DFT calculations substantiate the role of the proton-responsive ligand in the hydrogen-borrowing process.

Cyclic ketones were quickly and quantitatively converted to 5-, 6-, and 7-membered lactones, very important synthons, by treatment with Oxone, a cheap, stable, and nonpollutant oxidizing reagent, in 1 M NaH2PO4/Na2HPO4 water solution (pH 7). Under such simple and green conditions, no hydroxyacid was formed, thus making the adoption of more complex and non-eco-friendly procedures previously developed to avoid lactone hydrolysis unnecessary. With some changes, the method was successfully applied also to water-insoluble ketones such as adamantanone, acetophenone, 2-indanone, and the challenging cycloheptanone.

Solid-state incorporation of Sn into beta (β) zeolites is a fast and efficient method to obtain Lewis acidic Snβ catalysts with high activity. The present work emphasizes the fundamental role of the heat-treatment atmosphere in the solid-state incorporation of active Sn in zeolites. Via an array of characterization tools including N2-physisorption, X-ray diffraction, diffuse reflectance UV-vis spectrocopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and 119Sn M?ssbauer spectroscopy, it is shown that preheating under an inert atmosphere (pre-pyrolysis) prior to air-calcination affords Sn-β catalysts with the highest Sn dispersion and significantly less extra-framework SnO2 compared to the classic calcination. In situ characterization during pre-pyrolysis by temperature-programed decomposition-mass spectrometry, thermogravimetric analysis, and 119Sn M?ssbauer spectroscopy reveals the in situ generation of Sn(II)O species that are more mobile than Sn(IV)O2 species generated during calcination. This mobility property essentially enables the high Sn dispersion in Snβ. Based on this knowledge, active sites per catalyst weight are maximized while retaining high turn-over frequencies for the Baeyer-Villiger oxidation reaction (300 h-1 at 80 °C). For Lewis acid densities above 200 μmol·g-1, the catalytic activity unexpectedly leveled off to 93 mM·h-1, even under kinetic control. We tentatively ascribe the activity plateau to the incorporation of Sn in less favorable T-sites at high Sn-loadings.

An efficient protocol for the Cα-H heteroarylation of ethers, amides, and alcohols using air and light under mild conditions is described. The reaction is applicable to a wide spectrum of functional groups. The generation of C-radicals via photoinduced aerobic oxidation of ethers, amides, and alcohols is the key feature of the process. Control experiments suggest a radical pathway for the reaction.

Efficient catalytic oxidative C-C bond cleavage with dioxygen is useful and challenging to prepare oxygenated fine chemicals from biomass. Herein, we report a catalytic strategy for the preparation of γ-butyrolactone (GBL) by photocatalytic oxidation of tetrahydrofurfuryl alcohol (THFA), tetrahydrofurfuric acid (THFCA), or other furfural derivatives at room temperature under visible-light irradiation. Metal-free mesoporous graphitic carbon nitride was used as the photocatalyst and O2was used as the oxidant. The effects of various semiconductor catalysts, light sources with different wavelengths, and the reaction time on the photocatalytic oxidation of THFA to GBL were separately investigated. Furthermore, the reaction mechanism was investigated through serious control experiments and the reaction pathway was investigated through density functional theory (DFT) calculations.

The Mitsunobu inversion is one of the reliable methods for stereospecific substitution of chiral alcohols, but its deacylation step has limited the substrate scope. Here, we propose a new template of the Mitsunobu acylate that can be deacylated in non-alkaline treatments. The 3,4-dihydroxy-2-methylenebutanoate was selected as a template structure, and its acetonide- or bisTBS derivatives were synthesized. The latter especially showed excellent inversion efficiency (up to >99% ee) and good elimination performance for a series of secondary alcohols in near-neutral conditions. The results demonstrated the applicability of the new template for the substrates labile in alkaline conditions, such as a-hydroxyesters.

Utilizing a chiral bicyclic imidazole organocatalyst and adopting a continuous injection process, an alternative route has been developed for the efficient synthesis of chiral phthalidyl ester prodrugs via dynamic kinetic resolution of 3-hydroxyphthalides through enantioselective acylation (up to 99 % ee). The computational studies suggest a general base catalytic mechanism differing from the widely accepted nucleophilic catalytic mechanism. The structure analysis of the key transition states shows that the CH-π interactions and not the previously considered cation/π-π interactions between the catalyst and substrate is the dominant factor giving rise to the observed stereocontrol.

The invention relates to a method for synthesizing cyclopropanecarboxaldehyde from 1,4-butanediol. The method has the advantages of accessible raw materials, low cost and simple technique, can implement one-step reaction, has high efficiency, and can implement continuous operation.

Photocatalytic Minisci-type functionalization of pyridine with tetrahydrofuran (THF) proceeded using hydrogen peroxide (H2O2) and a TiO2photocatalyst under acidic conditions. Under UV light (λ= 360 nm), the reaction selectivity based on pyridine (Spy) was >99% while the selectivity based on THF (STHF) was low such as 19%. In contrast, under visible light (λ= 400 or 420 nm)Spywas similarly high (>99%) andSTHFwas two times higher than that under UV light. A surface peroxo complex formed upon contact of hydrogen peroxide with the TiO2surface can be selectively photoexcited by visible light to inject the photoexcited electron to the conduction band of TiO2. The electron can reduce H2O2to a reactive oxygen species (ROS) and promote selectively the Minisci-type cross-coupling reaction between pyridinium ions and THF. A reaction test with a hole scavenger (methanol) evidenced that the hole oxidation of H2O2under UV light is responsible for the lower selectivity, in other words, the higher selectivity under visible light would be due to suppression of the hole oxidation of H2O2. These results demonstrate a novel way to improve the selectivity of the photocatalytic cross-coupling reaction by using H2O2as an oxidant with the photoexcitation of surface Ti-peroxo species on TiO2

The acceptorless dehydrogenative cross-coupling of primary alcohols to form cross-esters with the liberation of H2 gas was enabled using a [RuCl(η6-C6H6)(κ2-CNP)][PF6]Cl complex as the catalyst. This sustainable protocol is applicable to a broad range of primary alcohols, particularly for the sterically demanding ones, featuring good functional group tolerance and high selectivity. The good catalytic performance can be attributed to the nitrogen-phosphine-functionalized N-heterocyclic carbene (CNP) ligand, which adopts a facial coordination mode as well as the facile dissociation of coordinated benzene.

The invention discloses a method for hydrogenolysis of halides. The invention discloses a preparation method of a compound represented by a formula I. The preparation method comprises the following step: in a polar aprotic solvent, zinc, H2O and a compound represented by a formula II are subjected to a reaction as shown in the specification, wherein X is halogen; Y is -CHRR or R; hydrogenin H2O exists in the form of natural abundance or non-natural abundance. According to the preparation method, halide hydrogenolysis can be simply, conveniently and efficiently achieved through a simple and mild reaction system, and good functional group compatibility and substrate universality are achieved.

The high-valent diiron(IV) intermediate Q is the key oxidant that cleaves strong C-H bonds of methane in the catalytic cycle of soluble methane monooxygenase (sMMO). sMMO-Q was previously reported as a bis-μ-oxo FeIV2(μ-O)2 diamond core but was recently described to have an open core with a long Fe···Fe distance. We recently reported a high-valent CoIII,IV2(μ-O)2 diamond core complex (1) that is highly reactive with sp3 C-H bonds. In this work, we demonstrated that the C-H bond cleaving reactivity of 1 can be further enhanced by introducing a Lewis base X, affording faster kinetic rate constants and the ability to cleave stronger C-H bonds compared to 1. We proposed that 1 first reacts with X in a fast equilibrium to form an open core species X-CoIII-O-CoIV-O (1-X). We were able to characterize 1-X using EPR spectroscopy and DFT calculations. 1-X exhibited an S = 1/2 EPR signal distinct from that of the parent complex 1. DFT calculations showed that 1-X has an open core with the spin density heavily delocalized in the CoIV-O unit. Moreover, 1-X has a more favorable thermodynamic driving force and a smaller activation barrier than 1 to carry out C-H bond activation reactions. Notably, 1-X is at least 4 orders of magnitude more reactive than its diiron open core analogues. Our findings indicate that the diamond core isomerization is likely a practical enzymatic strategy to unmask the strong oxidizing power of sMMO-Q necessary to attack the highly inert C-H bonds of methane.

Although radical formation from a trialkylborane is well documented, the analogous reaction mode is unknown for trihaloboranes. We have discovered the generation of bromine radicals from boron tribromide and simple proton sources, such as water ortert-butanol, under open-flask conditions. Cyclopropanes bearing a variety of substituents were hydro- and deuterio-brominated to furnish anti-Markovnikov products in a highly regioselective fashion. NMR mechanistic studies and DFT calculations point to a radical pathway instead of the conventional ionic mechanism expected for BBr3

Biomimetic flavin organocatalysts oxidize nitromethane to formaldehyde and NOx - providing a relatively nontoxic, noncaustic, and inexpensive source for catalytic NO2 for aerobic TEMPO oxidations of alcohols, diols, and ethers. Alcohols were oxidized to aldehydes or ketones, cyclic ethers to esters, and terminal diols to lactones. In situ trapping of NOx and formaldehyde suggest an oxidative Nef process reminiscent of flavoprotein nitroalkane oxidase reactivity, which is achieved by relatively stable 1,10-bridged flavins. The metal-free flavin/NOx/TEMPO catalytic cycles are uniquely compatible, especially compared to other Nef and NOx-generating processes, and reveal selectivity over flavin-catalyzed sulfoxide formation. Aliphatic ethers were oxidized by this method, as demonstrated by the conversion of (-)-ambroxide to (+)-sclareolide.

Selective oxidation of ethers to lactones with O2 as a benign oxidant using Au/CeO2 as the catalyst has been developed. The oxygen vacancies and Au0 species on the surface of CeO2 contribute to the activation of O2. The excellent selectivity of lactones is due to the adsorption of ethers and activation of the C(sp3)-H bond on Au/CeO2.

Succinic acid is a valuable biomass-derived platform molecule, which can be further catalytically converted into many industrially relevant molecules such as γ-butyrolactone, 1,4-butanediol or tetrahydrofuran. The influence of the support nature on both the activity of Ru/TiO2 catalysts and the selectivity pattern in the hydrogenation of succinic acid was investigated, with focus on the metal-support interaction, the crystallographic structure of the TiO2 support and the supported Ru nanoparticle size features. We showed that the catalyst activity was related to both the Ru particle size and the metal support interaction, those features being induced by the presence of the rutile phase within the TiO2 support and by the preparation method of the supported Ru particles. The rutile phase not only favors the formation of small Ru particles but also promotes stronger metal-support interaction compared with the anatase polymorph. Strong interactions between metal and support can also be formed via thermal reduction in contrast to low-temperature direct chemical reduction. Interestingly, a low temperature solar photon-assisted synthesis method facilitates very high succinic acid conversion, by enabling the stabilization of 1.8 nm small-size Ru nanoparticles in the absence of any rutile phase within the TiO2 support. This journal is

PROBLEM TO BE SOLVED: To provide a method for producing selectively alcohol from carboxylic acid under mild conditions. SOLUTION: In the presence of a catalyst with M1 and M2 as metal species supported on a support, a substrate is reduced to produce a corresponding alcohol. (M1 is Rh, Pt, Ru, Ir, or Pd; M2 is Sn, V, Mo, W, or Re; the support is ZrO2, hydroxyapatite, Nb2O5, fluoroapatite, or hydrotalcite; the substrate is the formula 1a, 1b, or 1c). SELECTED DRAWING: None COPYRIGHT: (C)2020,JPO&INPIT

Simple and efficient in situ generated palladium nanoparticles (PdNPs) in PEG-4OO catalyzed semi transfer hydrogenation of internal alkynes to Z-alkenes with excellent selectivity along with the formation of beneficial γ-butyrolactone as a byproduct using low quantity of safer and attractive 1, 4-butanediol as a hydrogen source was described.

An interesting chemiluminescence (CL) phenomenon of cyclic peroxides originating from tetrahydrofuran hydrogen peroxide (THF-HPO) in the presence of BSA-stabilized Au NCs (Au?BSA NCs) was found for the first time. In this CL system, Au?BSA NCs can greatly accelerate the decomposition of THF-HPO, and then chemiluminescence resonance energy transfer (CRET) occurs between excited dioxetane derivatives and the Au?BSA NCs, yielding enhanced CL emission which can be further enhanced more than 10 times by the addition of copper ions. Based on this, a synergistic CL nanoprobe with a special signal amplification strategy was developed.

Selective catalytic oxidative C?C bond cleavage with dioxygen is useful and challenging to prepare oxygenated fine chemicals. Herein we fabricated vanadium oxide–nitride composites as catalysts via a facile thermal treatment process, and the surface composition could be tuned by the thermal treatment temperature, which could affect catalytic oxidation of cyclohexanol significantly. By using such a V?N?C composite prepared at 500 °C, cyclohexanol could be selectively oxidized with dioxygen into lactones including δ-valerolactone and γ-butyrolactone, rather than common dicarboxylic acids. Cyclohexanone and 2-cyclohexen-1-one were verified as two key intermediates. V3+ species in the form of vanadium nitride and vanadium (III) oxide were detected, and well dispersed on amorphous carbon with a low degree of graphitization. These findings will provide a reference for catalytic oxidative C?C bond cleavage with molecular oxygen under mild reaction conditions.

A class of zwitterionic organocatalysts based on an amide anion/iminium cation charge pair has been developed. The zwitterions are easily prepared by reacting aziridines with aminopyridines. They are catalytically applicable to transesterifications and dehydrative esterifications. Mechanistic studies reveal that the amide anion and iminium cation work synergistically in activating the reaction partners, with the iminium cationic moiety interacting with the carbonyl substrates through nonclassical hydrogen bonding. The reaction can be applied to large-scale synthesis of biodiesel under mild conditions.

The general dehalogenation of alkyl halides with zinc using D2O or H2O as a deuterium or hydrogen donor has been developed. The method provides an efficient and economic protocol for deuterium-labeled derivatives with a wide substrate scope under mild reaction conditions. Mechanistic studies indicated that a radical process is involved for the formation of organozinc intermediates. The facile hydrolysis of the organozinc intermediates provides the driving force for this transformation.

Microenvironments in enzymes play crucial roles in controlling the activities and selectivities of reaction centers. Herein we report the tuning of the catalytic microenvironments of metal–organic layers (MOLs), a two-dimensional version of metal–organic frameworks (MOFs) with thickness down to a monolayer, to control product selectivities. By modifying the secondary building units (SBUs) of MOLs with monocarboxylic acids, such as gluconic acid, we changed the hydrophobicity/hydrophilicity around the active sites and fine-tuned the selectivity in photocatalytic oxidation of tetrahydrofuran (THF) to exclusively afford butyrolactone (BTL), likely a result of prolonging the residence time of reaction intermediates in the hydrophilic microenvironment of catalytic centers. Our work highlights new opportunities in using functional MOLs as highly tunable and selective two-dimensional catalytic materials.

An effective heterogeneous catalyst for ring-expansion carbonylation of epoxides may have additional advantages over the homogeneous counterpart in terms of facile product separation and recyclability. A new Al(iii) picket fence phthalocyanine complex was synthesized and directly knitted using the Friedel-Crafts reaction to prepare a solid porous network, which was ultimately used to immobilize [Co(CO)4]- ions. The resulting heterogeneous catalyst, [Lewis acid]+[Co(CO)4]-, efficiently catalyzes the conversion of various epoxides into the corresponding β-lactones with high selectivity (99%) and stoichiometric conversion under mild reaction conditions, along with good functional group tolerance.

Ruthenium-catalyzed formation of lactones from diols in aqueous medium has been demonstrated. 1,3,5-Triazaphosphaadamantane (PTA) included water-soluble ruthenium complexes [RuCl 2 (PPh 3)(2,6-Py-(CH 2 -PTA) 2 ]·2Br and [RuCl 2 (PPh 3) 2 (2-PyCH 2 PTA)]·Br in the presence of KOH were found to be efficient for the synthesis of lactones from diols. The reported synthetic protocol is green as it uses water as solvent, avoids the use of any hydrogen acceptor/oxidant, and produces hydrogen as the only side product. Mechanistic studies revealed that lactone formation involved aldehyde intermediate and followed dehydrogenative pathway.

Carbon nanotube sieves (CNTs-S) with a flutelike shape were synthesized by cutting and perforating using a chemical oxidation etching method. Using the obtained CNTs-S as a hard template, SiO2-coated CNTs-S dual pore structures (CNTs-S@SiO2) were formed. Finally, tungstophosphoric acid was supported on CNTs, CNTs-S, and CNTs-S@SiO2 matrices by the incipient wetness method to obtain the corresponding supported catalysts PW12/CNTs, PW12/CNTs-S, and PW12/CNTs-S@SiO2. The results showed that obtained 30%PW12/CNTs-S and 30%PW12/CNTs-S@SiO2 catalysts in 30 wt% dipping solution had the best catalytic performance for Baeyer–Villiger oxidation of cyclic ketones by H2O2. The conversion of cyclohexanone was 94% and 91%, respectively, in 5 min under microwave irradiation. Cyclopentanone and adamantanone approached quantitative conversion and the selectivity of corresponding lactones reached 100%. The dual pore structure catalyst showed very excellent cyclic stability.

Heterogeneous multiple-catalyst assemblies were developed in which the flavinium cation and Na or Li cations were easily immobilized on a chitin-derived anionic polymeric scaffold through noncovalent ionic interactions. The supramolecular flavinium catalysts were successfully employed in the environmentally friendly heterogeneous Baeyer–Villiger oxidation and sulfoxidation by H2O2. Owing to the cooperative catalytic effect of flavinium, alkali metal, and sulfated chitin, the supramolecular flavinium assembly showed higher catalytic activity for the Baeyer–Villiger oxidation of cyclic ketones than the corresponding homogeneous flavinium catalyst. Because the ionic assembly was stable under the reaction conditions, the catalyst could be readily recovered by simple filtration and reused.

Stability studies dedicated to high-energy compounds for a series of linear peracids (C6-C12), including sensitivity to mechanical impulse (shock and friction), as well as electrical (spark) and thermal sensitivity (temperature and heat of decomposition), were presented in this work for the first time. Studies revealed that all peracids were insensitive to shock, while in the case of the other sensitivity tests sharp differences between results for C8 and C10 peracids were observed. Taking into account the relatively high initial temperature of decomposition (above 64 °C) perdecanoic acid was selected as a safe alternative to commonly used hazardous short-chain peracids. Next, a new method for the Baeyer-Villiger oxidation was presented. Oxidation of 2-adamantanone was chosen as a model reaction. Peroctanoic, perdecanoic and perdodecanoic acids were tested as oxidants. Peroctanoic acid was the most reactive but taking into account both safety and kinetic issues, perdecanoic acid was selected for the further studies. The influence of reaction conditions on reaction rate was investigated. Optimized reaction conditions were suggested (two-fold molar excess of peracid with respect to the ketone, toluene as a solvent, 35 °C). This exploratory study offers promise with regard to the development of safer alternatives to peracetic acid in industrial oxidation.

Herein, a Ni/NiO composite catalyst was synthesized by a simple in situ reduction method, and its catalytic hydrogenation performance has been verified to be superior to that of noble metals. In particular, the catalysts can transform 2(5H)-furanone (HFO) to γ-butyrolactone (GBL) efficiently under mild conditions, which effectively upgrades the biomass-derivatives. The superior catalytic activity can be attributed to the synergism of the geometric construction and electronic regulation. Specifically, ultrathin NiO nanosheets contain plenty of surface defects and relatively large mesopores. Those defects can be helpful in the activation and dissociation of hydrogen, the adsorption of HFO molecules, as well as the enhancement of the local hydrogen concentration on the catalyst, while the pores can be considered as nano-reactors for hydrogenation. The strong interaction at the interface caused by the in situ synthesis can further tune its electronic structure and improve the hydrogen adsorption. In addition, the catalyst also displays great catalytic properties for p-nitrophenol (PNP) hydrogenation and non-enzymatic glucose sensing, which further supports the promising application potential of such catalysts with the unique mesostructures of Ni/NiO heterojunctions with defect-rich ultrathin nanosheets.

Gold-catalyzed oxidations of alkynes by N-oxides offer direct access to reactive α-oxo gold carbene intermediates from benign and readily available alkynes instead of hazardous diazo carbonyl compounds. Despite various versatile synthetic methods developed based on this strategy, one of the hallmarks of α-oxo carbene/carbenoid chemistry, that is, the Wolff rearrangement, has not been realized in this context. This study discloses the first examples that show the Wolff rearrangement can be readily realized by α-oxo gold carbenes oxidatively generated from TBS-terminated alkynes (TBS=tert-butyldimethylsilyl). The thus-generated silylketenes can be either isolated pure or subsequently trapped by various internal or external nucleophiles in one pot to afford α-silylated carboxylic acids, their derivatives, or TBS-substituted allenes.

TiO2-supported Mo carbides “MoC/TiO2” were prepared by impregnation of Mo salt followed by temperature programmed reduction-carburization using 20% v/v C2H6/H2. Catalysts were characterized by XRD, XPS, TEM, STEM, ICP, Raman, BET, and carbon elemental analysis. The catalytic activity was evaluated for aqueous phase hydrogenation of succinic acid at 160–240 °C, and 90–150 bar of H2 in batch reactor. MoC/TiO2 is active for this reaction. The main products after 24 h are γ-butyrolactone, and more remarkably butyric acid. These intermediates are then converted to tetrahydrofuran, butanol, 1,4-butanediol and butane. The reaction conditions (temperature, pressure) do not impact the products distribution. A larger amount of butyric acid is formed when catalysts were synthesized with a higher gas hourly space velocity. The deactivation observed while recycling the catalyst was mainly attributed to a decrease in the amounts of carbidic molybdenum and carbidic carbon, as demonstrated by XPS analysis.

To study the effect of acid-base properties of catalysts on 1,4-butanediol (BDO) dehydration to 3-buten-1-ol (BTO), Yb/Zr catalysts with different Yb content were synthesized by a wet impregnation method. The texture property, crystalline form and surface

A lactonization of various diols catalyzed by platinum on carbon (Pt/C) in water under an atmosphere of molecular oxygen was developed. Derivatives of 1,4- 1,5- and 1,6-diols were transformed into the corresponding five-, six-, and seven-membered lactones by the present oxidative lactonization method.

Oxidation of aliphatic α,ω-diols is a potentially interesting route to the production of valuable α,ω-diacids or ω-hydroxy acids for various polymer synthesis. 1,4-Butanediol (BDO), 1,5-pentanediol (PDO) and 1,6-hexanediol (HDO) are particularly attractive since they may be obtained from lignocellulosic biomass. The aqueous aerobic oxidation of these diols to the corresponding diacids was investigated in water over a set of Au, Pt, Au-Pt and Au-Pd catalysts supported on zirconia at 70 °C or 90 °C under 40 bar air. The nature of the metallic catalyst influenced the distribution of products as oxidation proceeded. The longer the carbon chain linking the terminal alcohol groups, the higher the yield of the diacid. The best yields of succinic acid, glutaric acid and adipic acid reached 83, 84 and 96% from BDO, PDO and HDO, respectively, over Au-Pt/ZrO2. There was some evidence of decarbonylation of the α,ω-hydroxyaldehyde at the early stage of the reaction. The presence of the hydroxyl substituent in 1,2,6-hexanetriol significantly slowed the oxidation rates compared with HDO. Besides, oxidation of PDO or HDO was highly selective to the ω-hydroxycarboxylate in moderate alkaline medium (NaOH/diol = 2) over Au/ZrO2 (90-93%).

Transfer hydrogenation using molecular catalysts has become a powerful tool in synthetic chemistry and a wide range of unsaturated substrates can be reduced with this protocol. Whereas reactions using iso-propanol as hydrogen donor are already well established, recent examples demonstrate the possibility to use linear alcohols from renewable resources. Herein, the first effective transfer hydrogenation of the challenging substrate carbon dioxide (CO2) directly to methanol is described, applying a molecular ruthenium catalyst and linear alcohols as the hydrogen source. In neat ethanol, TONs up to 121 are achieved under moderate pressures of CO2. Moreover, systematic investigations enable to propose initial acceptorless dehydrogenation of the alcohol, followed by the reduction of CO2 to methanol via ethyl formate, as mechanistic basis.

The growing pursuit of the viable application of γ-butyrolactone (GBL) as an industrially important product offers the possibility to use 1,4-butanediol (1,4-BDO) as a potential reactant. In this regard, different proportions of copper-based ceria catalysts (5, 10, 15, and 20CC) were synthesized using a wet impregnation method and their catalytic activities were tested for the vapour phase dehydrogenation of 1,4-BDO to GBL at temperatures from 240-300 °C. The synthesized copper-based ceria catalysts (5CC, 10CC, 15CC, and 20CC) were characterized using various analytical tools and the consequent results revealed that the activities of the CC catalysts were influenced by the physicochemical properties of the materials. In order to determine the influence of various supports on the catalytic activity, the addition of 10 wt% copper (Cu) to TiO2, Al2O3, ZnO, ZSM-5, and SBA-15 supports was carried out, and the respective influence on the catalytic activity was also experimentally established. The most outstanding catalytic activity was seen for the 10 wt% copper-based ceria catalyst, with a high conversion of 93% and selectivity of 98% at 240 °C. Factors like a high surface area, and better dispersion and basicity of active sites had a marked impact on the catalytic activity. Mechanistic analysis suggested that 1,4-BDO undergoes dehydrogenation over the copper surface to give 4-hydroxybutanal, followed by hemiacetylation and subsequent dehydrogenation to give GBL as the selective product. In terms of the stability of the catalysts, the 10 wt% copper-based ceria catalyst maintained a stable GBL selectivity of 98% for up to 7 h on-stream.

[Ru(tpy)(pyalk)Cl]Cl (pyalk = 2-(2′-pyridyl)-2-propanol) was synthesized and characterized crystallographically and electrochemically. Upon dissolution in water and acetonitrile, [Ru(tpy)(pyalk)Cl]Cl was found to form [Ru(tpy)(pyalk)Cl]+ and [Ru(tpy)(pyalk)(OH)]+, respectively. The Ru(ii/iii) couple of [Ru(tpy)(pyalk)Cl]+ was found to be relatively low compared to that of other Ru complexes in acetonitrile, but the Ru(iii/iv) couple was not significantly different than other Ru complexes bearing anionic ligands. Pourbaix diagrams were generated for [Ru(tpy)(phpy)(OH2)]+ (phpy = 2-phenylpyridine) and [Ru(tpy)(pyalk)(OH)]+ in water, and it was found that [Ru(tpy)(pyalk)(OH)]+ has a lower Ru(ii/iii) potential than [Ru(tpy)(phpy)(OH2)]+ under neutral to alkaline pH. [Ru(tpy)(pyalk)(OH)]+ was found to catalyze C-H bond hydroxylation of secondary alkanes and epoxidation of alkenes using cerium(iv) ammonium nitrate as the primary oxidant.

A novel catalytic system with a tripodal cobalt complex is developed for efficiently converting primary alcohols to esters. KOtBu is found essential to the transformation. A preliminary mechanistic study suggests a plausible reaction route that involves an initial Co-catalyzed dehydrogenation of alcohol to aldehyde, followed by a Tishchenko-type pathway to ester mediated by KOtBu.

The present invention relates to a novel phenonthroline based pincer complexes and process for preparation thereof. The present invention also provides a one pot process for the conversion of carbon dioxide to methanol in the presence of a molecularly defined pincer-type single-site Ru-catalyst and secondary amine. Further the present invention provides the use of phenonthroline based pincer complexes for the esterification of alcohols and hydrogenation of esters under mild conditions.

Several oxidative approaches namely thiocyanation of aromatic compounds, epoxidation of alkenes, amidation of aromatic aldehydes, epoxidation of α β-unsaturated ketones, oxidation of sulfides to sulfoxides and sulfones, bayer-villeger reaction, bromination and iodation of aniline and phenol derivatives oxidative esterification, oxidation of pyridines and oxidation of secondary, allylic and benzyllic alcohols were carried out using 1,1,2,2-Tetrahydroperoxy-1,2-Diphenylethane as the potential solid oxidant which can be stored for several months without any loss in its activity. All of the procedures were accomplished via mild reaction conditions and the products were afforded in high yields and short reaction times.

A tetradentate nitrogen ligand containing a benzimidazole ring and an electron-rich pyridine ring was developed, the resulting manganese complex exhibited good activity in the C?H oxidation of simple alkanes. In particular, cyclic aliphatic alkanes were transformed into ketones in very good yields (up to 89 %) by using environmentally benign H2O2 as the terminal oxidant. This protocol was also applied successfully in benzylic C?H oxidation, giving the corresponding ketones with very good selectivities. In addition, tertiary C?H bond oxidation of complex molecules by the manganese complex showed potential utility for assembling alcohols with good selectivity in late-stage chemical synthesis.