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The fungal macrolide berkeleylactone A was synthesised in 13 steps and 24% yield using (R)-propylene oxide and an asymmetric Noyori hydrogenation of a β-ketoester to install the stereogenic centres. A domino addition-Wittig olefination of a 13-hydroxytetradecanal intermediate with the cumulated ylide Ph3PCCO closed the macrocyle by establishing the α,β-unsaturated ester group, necessary for the attachment of the sidechain thiol via a thia-Michael reaction. The synthetic berkeleylactone A inhibited the formation of Staphylococcus aureus biofilms and showed significant dispersive effects on preformed biofilms of Candida albicans by at least 45% relative to untreated controls at concentrations as low as 1.3 μg mL-1.

A flexible, enantioselective route to highly functionalized α,β-unsaturated δ-lactones has been applied to the synthesis of 7-aza-phomopsolide E and its C-4 epimer. This approach relies on the application of the Noyori asymmetric hydrogenation of furyl ketone to produce the secondary furyl alcohol in high enantioexcess, which can be stereoselectively transformed into α,β-unsaturated-δ-lactones by a short, highly diastereoselective oxidation and reduction sequence. DCC and acid chloride couplings were used to introduce the side chains of the two natural product analogues.

We describe here an enantioselective synthesis of (+)-EBC-23, a potent anticancer agent from the Australian rainforest. Our convergent synthesis features a [3+2] dipolar cycloaddition of an olefin-bearing 1,3-syn diol unit and an oxime segment containing 1,2-syn diol functionality as the key step. The segments were synthesized in a highly enantioselective manner using Noyori asymmetric hydrogenation of a β-keto ester and Sharpless asymmetric dihydroxylation of an α,β-unsaturated ester. Cycloaddition provided isoxazoline derivative which upon hydrogenolysis furnished the β-hydroxy ketone expediently. A one-pot, acid-catalyzed reaction removed the isopropylidene group, promoted spirocyclization, constructed the complex spiroketal lactone core, and furnished EBC-23 and its C11 epimer. The C11 epimer was also converted to EBC-23 by chemoselective oxidation and reduction sequence. The present synthesis provides convenient access to this family of natural products in an efficient manner.

"Kinetic Approach to the Catalytic Hydrogenation of Nitroaliphatic Compounds, V. Dubois, G. Jannes, J. L. Dallons, and A. Van Gysel New Route to m-Aminophenol, Stephen E. Jacobson A New and Improved Synthesis of N-Butyl-1-Deoxynojirimycin, Mike G. Scaros, Michael L. Prunier, Rick J. Rutter, Peter K. Yonan, Roy Grabner, and Bryan Landis Homogeneous Asymmetric Catalysis as an Important Tool for the Production of Fine Chemicals and Pharmaceutical Products, A. S. C. Chan, S. A. Laneman, R. E. Miller, J. H. Wagenknecht, and J. P. Coleman The Use of a Fischer-Porter Apparatus for Chiral Homogeneous Catalytic Hydrogenation, Louis S. Seif, Daniel A. Dickman, Donald B. Konopacki, and Bryan S. Macri Application of Symmetric Catalysis to the Synthesis of Peptide Mimics, John T. Talley, Cathleen E. Hanau, Gary A. DeCrescenzo, and Michelle A. Schmidt Catalytic Amination of Alcohols and Its Potential for the Synthesis of Amines, Alfons Baiker High Selectivities in Hydrogenation of Halogenonitrobenzenes on Pd, Pt, or Raney Nickel as Catalysts, Georges Cordier, Jean Michel Grosselin, and Rose Marie Bailliard Solid-Acid-Catalyzed o-Tolidine Alkylation: Scope, Limitations, and Product Utility, Kevin R. Lassila, Michael E. Ford, Susan M. Clift, Jeremiah P. Casey, and Paula L. McDaniel Comparative Catalytic Hydrogenation Reactions of Aliphatic Dinitriles over Raney Nickel Catalysts, Marc Joucla, Philippe Marion, Pierre Grenouillet, and Jean Jenck Hydrogenation of Nitrosobenzene over Palladium Catalysts, Gerard V. Smith, Ruozhi Song, Marian Gasior, and Russell E. Malz, Jr. Past, Present, and Future of Catalytic Oxidation of Hydrocarbons, Jerzy Haber Oxidation of Glucose on Palladium Catalysts: Particle Size and Support Effects, M. Besson, P. Gallezot, F. Lahmer, G. FlEche, and P. Fuertes A Method for the Preparation of Pyromellitic Acid from Durene via Liquid Phase Oxidation, Walt Partenheimer Surface Chemistry and Engineering of HCN Synthesis, L. D. Schmidt and D. A. Hickman New Technology for Olefin Oxidation to Carbonyls Using a Palladium and Polyoxoanion Catalyst System, John H. Grate, David R. Hamm, and Suresh Mahajan Side Reactions in Reductive Alkylation of Aromatic Amines with Aldehydes and with Ketones, Harold Greenfield A Frontier Molecular Orbital Determination of the Active Sites on Dispersed Metal Catalysts, Robert L. Augustine and Konstantinos M. Lahanas Hydrogenations and Other Reactions on Titanium Mixed Metal Oxides, Gether Irick and Patricia N. Mercer Methacrylate Esters via the Homogeneous Carbonylation of 2-Bromopropene, Robert A. DeVries, Robert T. Klun, John W. Hull, Jr., and Kim A. Felty Production of Phenols from Haloaromatics in the Presence of Copper-Exchanged Zeolites: Synthesis of the Catalyst and Mechanistic Study, G. Perot, Y. Pouilloux, M. Guisnet, and M. Gubelmann Polymer-Bound Dialkylaminopyridine Catalysts: Synthesis and Applications, James G. Keay and Eric F. V. Scriven Metal Incorporation into Copper Aluminum Borates: Catalyst Structure and Catalytic Role in Dehydrogenation and Dehydrocyclization, Larry C. Satek and Patrick E. McMahon Amidation of Methyl Esters with Formamides in the Presence of KCN as the Catalyst, A. Benderly, L. Y. Dennis, and A. Bravo New Titanium Silicate Molecular Sieves: Properties and Catalysis, M. Deeba, C. F. Keweshan, G. S. Koermer, S. M. Kuznicki, and R. S. Madon Transvinylation Catalysts for the Production of Higher Vinylic Esters of Vinyl Acetate, F. J. Waller Protecting the Ozone Layer: Catalytic Synthesis of CFC Alternatives, Leo E. Manzer The Tertiary Organometallic Reagent Promoted Reductive Coupling of Aryl Halides, Thomas A. Puckette Catalysis of Organic Reactions by Inorganic Solids, Pierre Laszlo Preparation of Pharmaceutical Intermediates Using Zeolite Catalysis: Preparation of 4-Methylthiazole with ZSM-5, F. P. Gortsema, B. Beshty, J. J. Friedman, D. Matsumoto, J. J. Sharkey, G. Wildman, T. J. Blacklock, and S. H. Pan Hydrocarbon Fragmentation Patterns on Rhodium Surfaces, Shane L. Anderson, Dinesh Kalakkad, and Abhaya K. Datye Catalytic Cracking of Organic Amides: A Key Step in the Production of a New Specialty Polymer, G. E. Parris and J. N. Armor Production of Low-Cost Aliphatic Isocyanates, P. L. Brusky, J. H. Kyung, and R. A. Grimm Catalytic Oxidation of Secondary Alcohols, Robert L. Augustine and Lisa K. Doyle Synthesis of Bisaniline A and Derivatives with Perfluorinated Sulfonic Acid Resins, Michael E. Ford and Mark D. Conner Effect of Water on the Oxidation of 2-Butanone over V2O5, Ismat Jahan and H. H. Kung H2-Hydrogenation of Nitriles Catalyzed by Ruthenium Ditertiaryphosphine Complexes, Ajey M. Joshi, Kenneth S. MacFarlane, Brian R. James, and Piero Frediani Enhancement of CO Hydrogenation Activity of Pt Catalysts by CeO2 and TiO2 Supports, Dinesh Kalakkad and Abhaya K. Datye Hydrocarbon Conversion Reactions overt he Pt-Re Bimetallic Catalysts Modified by Sulfur, Changmin Kim and Gabor A. Somorjai Activation of Esters for Hydrogenolysis on Copper Titanias, Yeong-Jen Kuo, Patricia N. Mercer, and Gether Irick The Direct Conversion of Vinyl to Ethylidyne, Z. M. Liu, X. L. Zhou, D. A. Buchanan, J. Kiss, and J. M. White Hydrocarbon Probes for the Study of Acidity on Oxide Surfaces, C. R. Narayanan, S. Srinivasan, and Abhaya K. Datye Synthesis of (+)-Apopinene by Decarbonylation of (+)-Myrtenal: Application of the Mechanisms of Hydrogenation and Decarbonylation, Gerard V. Smith and Ruozhi Song New Hydrogenation Apparatus, Robert L. Augustine, Setrak K. Tanielyan, and Glenn Wolosh A Pd-Sn Catalyst for Toluene Acetoxylation, Setrak K. Tanielyan and Robert L. Augustine Characterization of Sulfided Platinum and Palladium Catalysts, D. S. Thakur, B. D. Roberts, T. J. Sullivan, G. T. White, N. Brungard, E. Waterman, and M. Lobur Selective Hydrogenation of Unsaturated Aldehydes over Silica- and Zeolite-Supported Metals, Akshay Waghray, Rachid Oukaci, and Donna G. Blackmond "

We report the design of a new iron catalyst for the asymmetric transfer hydrogenation of ketones. This type of iron catalyst combines the structural characteristics of the Noyori hydrogenation catalyst (an axially chiral 2,2'-bis(phosphino)-1,1'-binaphthyl fragment and the metal-ligand bifunctional motif) and an ene(amido) group that can activate the iron center. After activation by 8 equivalents of potassium tert-butoxide, (SA,RP,SS)-7a and (SA,RP,SS)-7b are active but nonenantioselective catalysts for the transfer hydrogenation of acetophenone and α,β-unsaturated aldehydes at room temperature in isopropanol. A maximum turnover number of 14480 was observed for (SA,RP,SS)-7a in the reduction of acetophenone. The right combination of the stereochemistry of the axially chiral 2,2'-bis(phosphino)-1,1'-binaphthyl group and the carbon-centered chiral amine-imine moiety in (SA,RP,RR)-7b' afforded an enantioselective catalyst for the preparation of chiral alcohols with moderate to good yields and a broad functional group tolerance.

A practical method for the asymmetric transfer hydrogenation of alpha-substituted ketones was developed utilizing oxo-tethered N-sulfonyldiamine-ruthenium complexes. Reduction by HCO2H and HCO2K in a mixed solvent of EtOAc/H2O allowed for the selective synthesis of halohydrins from 2-bromoacetophenone (98%) and 2-chloroacetophenone (>99%), leading to suppressed undesired side reactions stemming from formylation under the typical reaction conditions using an azeotropic 5:2 mixture of HCO2H and Et3N. A range of functional groups, such as halogens, methoxy, nitro, dimethylamino, and ester groups, were well tolerated, highlighting the potential of this method. Nearly complete selectivity with a preferable ee was maintained even with a substrate/catalyst (S/C) ratio of 5000. This catalyst system was also effective for the asymmetric reduction of alpha-sulfonated ketones without eroding the leaving group.

The complexes [Ir(COD)(PR3)2]PF6 (R = PPh3 (1); R = PBn3 = tribenzylphosphine (2)), [Ir(COD)(PBn3)(PAn3)]PF6 (3) (PAn3 = Tri-orthoanisyl-phosphine) and cis-(P,P)-[IrH(COD)(PBn3){η2-P,C-(C6H4CH2)PBn2}]PF6 (4) are active in the transfer hydrogenation of ketones. However, complex (3) gives the best results in conversion toward the alcohol. Interestingly, commercial isopropanol was used as hydrogen source, without any drying treatment. In situ generated isopropoxide was used as base. An efficient conversion of a variety of ketones, aromatic or aliphatic, cyclic or linear, including molecules with conjugated or isolated C C moieties was achieved, thus reporting 12 examples of hydrogenated substrates. Ketones of higher steric hindrance could not be converted under the studied conditions. The experimental evidence indicates that the steric and electronic properties of the substrates are determinant in the observed conversions and performance of the system. For α,β-unsaturated ketones, preference toward the reduction of the C C bond was observed. However, the system shows chemoselectivity toward the carbonyl group in molecules which also bear an isolated C C moiety. With the results obtained, a pseudo first-order dependence of the reaction rate on the concentration of ketone was determined. Also, stoichiometric as well as in situ tests were performed to shed light into the reaction pathways possibly involved in the catalytic TH of ketones described herein (precursor 3, base and isopropyl alcohol as hydrogen source).

Chiral secondary alcohols are ubiquitous motifs in numerous natural products, pharmaceuticals, and biological active compounds. Catalytic asymmetric hydrogenation of multi-functionalized ketones provides an effective and powerful synthesis method to construct chiral secondary alcohols. In the asymmetric hydrogenation of multi-functionalized ketones, the simultaneous coordination of the carbonyl oxygen of ketones and adjacent functional groups to central metal of the catalyst is the key factor for the asymmetric induction. However, for ketones with two adjacent coordinating groups, the competitive ligation of the adjacent coordinating groups to central metal tends to decrease the enantioselectivities. In this review, we summarized the know how in achieving high chemo-, enantio-, and diastereoselectivities in asymmetric hydrogenation of multi-functionalized ketones, i.e. to change the bulkiness and/or electronic properties of the coordinating groups in substrates and in ligands, or to introduce a third coordinating ligand (solvent) to make one coordination much more stronger than the other.

As an extension of the reaction mechanism describing the base-catalyzed hydrogenation of ketones according to Berkessel et al., we use a standard methodology for transition-state (TS) calculations in order to check the possibility of heterolytic cleavage of H2 at the ketone's carbonyl carbon atom, yielding one-step hydrogenation path with involvement of carboxylic acid as a catalyst. As an extension of the catalyst scope in the base-catalyzed hydrogenation of ketones, our mechanism involves a molecule with a labile proton and a Lewis basic oxygen atom as a catalyst-for example, R-C(=O)OH carboxylic acids-so that the heterolytic cleavage of H2 could take place between the Lewis basic oxygen atom of a carboxylic acid and the electrophilic (Lewis acidic) carbonyl carbon of a ketone/aldehyde. According to our TS calculations, protonation of a ketone/aldehyde by a proton shuttle (hydrogen bond) facilitates the hydride-type attack on the ketone's carbonyl carbon atom in the process of the heterolytic cleavage of H2 . Ketones with electron-rich and electron-withdrawing substituents in combination with a few carboxylic and amino acids-in total, 41 substrate-catalyst couples-have been computationally evaluated in this article and the calculated reaction barriers are encouragingly moderate for many of the considered substrate-catalyst couples.

In the challenging α,β-unsaturated aldehydes and ketones hydrogenation to unsaturated alcohols (UA), Ru–Au/MCM-41 exhibits superior high activity and selectivity compared with monometallic Ru. TEM and XRD measurements were applied to characterize as-prepared Ru/MCM-41 and Ru–Au/MCM-41 catalysts. The results indicated that the addition of Au significantly improved the dispersion of the metallic Ru components, thus enhancing the activity of the catalyst. The enhancement of selectivity to UA could be attributed to the interaction of Ru and Au components in the support and the morphology effect of Ru, which are revealed by in-suit DRIFTS, H2-TPD, XPS, and FTIR measurements. The morphological and electronic aspects of Ru particles lead to a favorable adsorption of C=O bond versus C=C bond. A dramatic increase in activity and selectivity of the reactions were observed upon the addition of Au, suggesting that the significant synergistic effects between Ru and Au play an important role in the activity and selectivity of the reaction. It is the first time that chemoselective hydrogenation of α,β-unsaturated aldehydes and ketones were studied on Ru–Au/MCM-41 catalysts.

This paper presented a study on the role of yttrium addition to Ru-based catalysts for liquid phase paranitrotoluene hydrogenation reaction. An impregnation-precipitation method was used for preparation of a series of yttrium doped Ru/NaY catalysts with yttrium content in the range of 0.0026-0.0052 g/g. Properties of the obtained samples were characterized and analyzed by X-ray diffraction (XRD), H-2-TPR, Transmission electron microscopy (TEM), ICP atomic emission spectroscopy, and Nitrogen adsorption-desorption. The results revealed that catalytic activity of NaY supported Ru catalysts increased with the yttrium content at first, then decreased with the further increase of yttrium content. When yttrium content was 0.0033 g/g, a Ru-Y/NaY2 catalyst showed the most excellent performance of paranitrotoluene hydrogenation reaction (paranitrotoluene conversion and the selectivity toward P-methyl-cyclohexylamine reached 99.9% and 82.5%, respectively). In addition, to compare with the performance of Ru-Y/NaY catalysts, the active carbon supported Ru catalysts were prepared using the same method in view of its higher surface area and adsorption capacity. Finally, the effect of solvent on the reaction over Ru-Y/NaY2 catalyst has been investigated, it was found that the best performance of paranitrotoluene hydrogenation reaction took place in protic solvents (isopropanol and ethanol). This was mainly ascribed to their polarity and hydrogen-bond accepting capability.

A ruthenium (II) N-heterocyclic carbene (NHC) complex was synthesized to investigate ligand dissociation as a possible deactivation pathway for the catalytic cycle of a transfer hydrogenation reaction. Diiodo(1,3-dimethylbenzimidazole-2-ylidene)(p-cymene)ruthenium(II) was synthesized for use as the catalytic species and characterized using physico-chemical, spectroscopic methods, and single crystal X-ray diffraction. The transfer of hydrogen from isopropanol to acetophenone was followed using 1H NMR. We observed 94% conversion of the substrate to the alcohol product after 1 h. We also found that the p-cymene complex decomposed during the catalytic reaction to the extent of 80% deactivation after 1 h, based on 1H NMR spectrometry. From Gaussian calculations, an ultraviolet–visible spectrum that is in excellent agreement with the actual spectrum was computed, giving insight into the nature of the absorptions observed experimentally.

We report carbon can be activated as metal-like hydrogenation catalyst for selective hydrogenation of nitroarenes. Using DFT calculations we demonstrated the combination of P-dopant and lattice defect in carbon can cause significant electron delocalization and change the band structure as metal-like one, and thus both H2 and nitro group are easily activated for selective hydrogenation. Then we fabricated this carbon catalyst with tunable concentration of P-dopant and lattice defect by polymerization and carbonization of phytic acid, and found the concentration of lattice defect is closely related to that of P-dopants. The synthesized catalyst exhibits superior catalytic activity, perfect selectivity and stability in the hydrogenation of nitroarenes, outperforming the reported metal-free, metal-oxide and nickel catalysts. Importantly, the hydrogenation activity is linearly dependent on the P-doping and/or defect concentration, perfectly agreeing with the DFT calculation. This work is expected to provide a cheap way for large-scale production of anilines using metal-like carbon catalyst.

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A series of bulky pyridine-bridged NHC-Ru complexes have been rationally designed and synthesized; these exhibited very high catalytic activity in the hydrogenation of cyclic and linear carbonates under mild reaction conditions. In the presence of catalytic amounts of a weak base, a broad range of substrates with different ring size and steric bulk were well tolerated, providing methanol and the corresponding diols in excellent yields with a catalyst loading as low as 0.5 mol %.

Rational design of catalysts for asymmetric transformations is a longstanding challenge in the field of catalysis. In the current contribution we report a catalyst in which a hydrogen bond between the substrate and the catalyst plays a crucial role in determining the selectivity and the rate of the catalytic hydrogenation reaction, as is evident from a combination of experiments and DFT calculations. Detailed insight allowed in silico mutation of the catalyst such that only this hydrogen bond interaction is stronger, predicting that the new catalyst is faster. Indeed, we experimentally confirmed that optimization of the catalyst can be realized by increasing the hydrogen bond strength of this interaction by going from a urea to phosphine oxide H‐bond acceptor on the ligand.

Metal catalyzed reductive couplings of π-unsaturated reagents with carbonyl compounds via hydrogenation or transfer hydrogenation has emerged as an alternative to the use of stoichiometric organometallic reagents in carbonyl addition.

An inorganic-organic hybrid catalyst, Ru(II)Cym@PMOB, was synthesized by anchoring of [Ru(II)Cl2(p-cymene)]2 complex which is derived from a reaction between hydrated ruthenium(III) trichloride and α-phellandrene over aminofunctionalized benzene-organosilica (PMOB). In the context of secondary alcohol synthesis from ketones, transfer hydrogenation (TH) reactions are convenient compared to conventional hydrogenation reactions owing to its lower activation energy and ambient pressure and mild temperature reaction conditions. The synthesized catalysts were characterized by CHN analysis, XRD, ICP, N2-sorption analysis, TG & DTA, FTIR, 13C & 29Si solid NMR, UV–vis, TEM, SEM and XPS. The catalytic activities of neat [Ru(II)Cl2(p-cymene)]2 complex and Ru(II)Cym@PMOB were evaluated in transfer hydrogenation (TH) of ketones (∼97%) and compared with conventional hydrogenation reactions (∼5%) where molecular H2 was used. The results showed Ru(II)Cym@PMOB as highly active catalyst towards transfer hydrogenation (TH) reaction of acetophenones compared to neat [Ru(II)Cl2(p-cymene)]2 complex. The heterogeneity of Ru(II)Cym@PMOB was confirmed by Sheldon’s test.

A chemoselective continuous-flow hydrogenation of aldehydes catalyzed by a dispersion of platinum nanoparticles in an amphiphilic polymer (ARP-Pt) has been developed. Aromatic and aliphatic aldehydes bearing various reducible functional groups, such as keto, ester, or amide groups, readily underwent flow hydrogenation in aqueous solutions within 22 s in a continuous-flow system containing ARP-Pt to give the corresponding primary benzylic or aliphatic alcohols in ≤99% yield with excellent chemoselectivity. Moreover, the long-term continuous-flow hydrogenation of benzaldehyde for 8 days was realized, and the total turnover number of the catalyst reached 997. The flow hydrogenation system provides an efficient and practical method for the chemoselective hydrogenation of aldehydes bearing reducible functional groups.

Herein, we report a heterogeneous TiO2-supported Re catalyst (Re/TiO2) that promotes various selective hydrogenation reactions, e.g. hydrogenation of esters to alcohols, hydrogenation of amides to amines, and N-methylation of amines using H2 and CO2. Initially, Re/TiO2 was evaluated in the context of the selective hydrogenation of 3-phenylpropionic acid methyl ester to afford 3-phenylpropanol (pH2 = 5 MPa, T = 180 oC), where revealed a superior performance relative to other catalysts explored in this study. In contrast to other typical heterogeneous catalysts, Re/TiO2 did not produce dearomatized byproducts. DFT studies suggested that the high selectivity for the formation of alcohols in favor of the hydrogenation of aromatic rings, should be ascribed to the higher affinity of Re toward the -COOCH3 group relative to the benzene ring. Re/TiO2 is moreover recyclable and shows a wide substrate scope for the reaction (19 examples). Subsequently, Re/TiO2 was applied to the hydrogenation of amides and the N-methylation of amines with H2 and CO2. Furthermore, Re/TiO2 promotes the N-alkylation of amines with carboxylic acids or esters in the presence of H2.

By using a copper transmetalation reagent [Cu(Kaibene)2]I, the NHC ligand (S,S)-MeNC3H2NCHPhCHPhNH2 “Kaibene” was transferred to ruthenium to make a precatalyst [RuCp*(Kaibene)(MeCN)](PF6) (Cp* = 1,2,3,4,5-pentamethylcyclopentadienyl), 7, in high yield as a mixture of two diastereomers. Under relatively mild conditions (0.02 mol % Ru, 0.16 mol % KOtBu, iPrOH, 50 °C, 25 bar of H2), this compound catalyzes the hydrogenation of aryl ketones and one alkyl ketone effectively with excellent activity and productivity (TOF up to 48 s–1, TON up to 104). At higher hydrogenation pressure (46 bar), the catalytic hydrogenation of N-phenyl-benzylimine to the corresponding amine is efficiently achieved. The hydrogenation of prochiral ketones resulted in low ee (35% for 4-chloroacetophenone). NMR spectroscopy was used to observe diastereomeric hydrides RuCp*(Kaibene)(H) 13-R/S that were generated by reaction of 7 with H2 and base in THF-d8. Complementary DFT studies suggest that either the heterolytic splitting of dihydr...

Dimeric pincer-type ruthenium(II)-NNN complexes bearing an unsymmetrical pyrazolyl-pyridylamino-pyridine ligand were prepared and characterized by NMR, elemental analysis, and X-ray single crystal structural determination. These complexes exhibited very high catalytic activity for both transfer hydrogenation of ketones and acceptorless dehydrogenation of secondary alcohols, achieving TOF values up to 1.9 × 106 h–1 in the transfer hydrogenation of ketones. The high catalytic activity of the Ru(II) complex catalysts is attributed to the presence of the unprotected NH functionality in the ligand and hemilabile unsymmetrical coordination environment around the central metal atoms in the complex.

The acetophenone (1a) reduction using catalytically active nickel complexes and water is an efficient and sustainable method to access a new methodology of transfer hydrogenation of ketones. When triethylsilane (Et3SiH) was used as sacrificial agent to promote the transfer hydrogenation from water, 1-phenylethanol (2a) was obtained in excellent yield along with silanol (Et3SiOH) as the reaction’s driving force. Deuterium labeling studies were made using Et3SiD or D2O and these studies showed that both compounds participate as hydride sources for the ketone reduction. A scope of substrates was assessed, including a variety of mono/diketones, and α,β-unsaturated ketones, to yield the corresponding secondary alcohols and saturated ketones. Additionally, asymmetric transfer hydrogenation of mono-ketones was studied for the mixture of nickel/(bisphosphine or phospholane) as catalyst precursor, using H2O/Et3SiO system and ethanol as hydrogen sources.

Selective hydrogenation reaction over supported metal nanoparticles (NPs) through activation of molecular H2 is very demanding in the context of maintaining atom efficiency in chemical reactions. Although high selectivity is difficult to achieve in the reaction, but it is very challenging. In this research, we separately deposited Pd and Pt NPs on nanoporous hollow polymer tubes (PP-3) and studied their efficiency in hydrogenation of α,β-unsaturated aldehydes as substrates. We found hydrogenation selectivity over these two types of catalysts (Pd@PP-3 and Pt@PP-3) were entirely different. Pt@PP-3 shows high selectivity in the hydrogenation of C=O bonds, producing unsaturated alcohol in high yield, whereas Pd@PP-3 only hydrogenates C=C bonds and forms saturated aldehyde as the major product. Pd@PP-3 and Pt@PP-3 were thoroughly characterized by PXRD, N2 sorption, TEM, XPS, CO stripping experiment and in-situ CO adsorption FT-IR studies. Our research implies the utility of porous organic polymers as support for metal NPs mediated hydrogenation reactions.

The hydride isonitrile complex [FeH(CNCEt3)(1a)]BF4 (2) containing a chiral P2(NH)2 macrocycle (1a), in the presence of 2-propanol as hydrogen donor, catalyzes the base-free asymmetric transfer hydrogenation (ATH) of prostereogenic ketones to alcohols and the hemihydrogenation of benzils to benzoins, which contain a base-labile stereocenter. Benzoins are formed in up to 83% isolated yield with enantioselectivity reaching 95% ee. Ketones give the same enantioselectivity observed with the parent catalytic system [Fe(CNCEt3)2(1a)] (3a) that operates with added NaOtBu

A new chiral manganese PNP pincer complex is described. The asymmetric hydrogenation of several prochiral ketones with molecular hydrogen in the presence of this complex proceeds under mild conditions (30-40 °C, 4 h, 30 bar H2 ). Besides high catalytic activity for aromatic substrates, aliphatic ketones are hydrogenated with remarkable selectivity (e.r. up to 92:8). DFT calculations support an outer sphere hydrogenation mechanism as well as the experimentally determined stereochemistry.

Asymmetric hydrogenation of α-substituted ethenylphosphonic acids has been successfully achieved by Rh/ferrocenyl chiral bisphosphorus ligand (SPO-Wudaphos) through noncovalent ion-pair interaction between the substrate and catalyst under mild reaction conditions without base. A series of chiral phosphonic acids were obtained with excellent results (up to 98% ee, >99% conversion, 2000 TON). Moreover, the control experiments showed that the noncovalent ion-pair interaction was critical in this asymmetric hydrogenation.

A stereoselective hydrogenation of 1,3-diynes with an air-stable copper(I)/N-heterocyclic carbene complex, [IPrCuOH], has been developed. The corresponding products, 1,3-dienes, are obtained in a stereoselective manner depending on their substitution pattern: Diaryl-diynes yield E,E-1,3-dienes, whereas dialkyl-diynes are converted to the corresponding Z,Z-1,3-dienes. Hydrogenation and deuteration experiments with enynes indicate that these are competent reaction intermediates in the hydrogenation of diynes.

The use of the complex [Ru3(CO)12] (1) as a catalyst precursor (0.1 mol%) at 200 °C, 60 psi of H2, along with triphenylphosphine (TPP) generated ruthenium nanoparticles (Ru-Nps); this occurred in the presence of pyridine-nitriles leading to a variety of hydrogenation (secondary amine, imine, or imidazole) products, depending of the pyridine-nitrile used, under similar reaction conditions. This relates to relatively good to modest yields, determined by the substituents in the corresponding pyridine. In sharp contrast, the use of aromatic dinitriles did not generate Ru-Nps at 140 °C, 150 psi of H2 and TPP, but allowed the homogeneous catalytic hydrogenation of the 1,4- and 1,3-dicyanobenzenes, to yield the corresponding CN-substituted secondary amine or imine. The main products were characterized by different analytical methods and spectroscopic techniques.

We successfully developed asymmetric hydrogenation of β-silyl-α,β-unsaturated esters to prepare chiral 3-substituted-3-silylpropionic ester products catalyzed by rhodium/bisphosphine-thiourea (ZhaoPhos) with excellent results (up to 97% yield, >99% ee, 1 500 TON). Moreover, our hydrogenation product can be efficiently converted to other important organic molecules, such as chiral ethyl (R)-3-hydroxy-3-phenylpropanoate, (R)-3-(dimethyl(phenyl)silyl)-3-phenylpropanoic acid.

Synthesis of (S)-5-fluoro-3-methylisobenzofuran-1(3H)-one (6), a key intermediate to lorlatinib, is described. A few synthetic methodologies, that is, boron reduction, enzymatic reduction, asymmetric hydrogenation, and asymmetric transfer hydrogenation, were evaluated for the chiral reduction of the substituted acetophenone intermediate (8). A manufacturing process, on the basis of the asymmetric transfer hydrogenation, was developed. This process was successfully scaled up to prepare 400 kg of 6.

Being the third most abundant transition metal in the Earth’s crust (after iron and titanium) and less toxic, reactions catalyzed by manganese are becoming very important. A large number of manganese complexes have been synthesized using bidentate and tridentate ligands. Such manganese complexes display excellent catalytic activities for various important organic transformations, such as hydrogenation, dehydrogenation, dehydrogenative coupling, transfer hydrogenation reactions, etc. In this short review, recent developments of such manganese-catalyzed reactions are presented.1 Introduction2 Well-Defined Manganese-Complex-Catalyzed Hydrogenation Reactions2.1 Hydrogenation of Nitriles2.2 Hydrogenation of Aldehydes and Ketones2.3 Hydrogenation of Esters2.4 Hydrogenation of Amides2.5 Hydrogenation of Carbon Dioxide3 Manganese-Catalyzed Dehydrogenation Reactions3.1 Selective Dehydrogenation of Methanol3.2 Dehydrogenative N-Formylation of Amines by Methanol3.3 Dehydrogenative Coupling Reactions of Alcohols3.4 Imine Synthesis via Dehydrogenative Coupling of Alcohols and Amines3.5 Synthesis of N-Heterocycles via Dehydrogenative Coupling4 Manganese-Catalyzed Dehydrogenation–Hydrogenation Cascades4.1 N-Alkylation of Amines with Primary Alcohols4.2 α-Alkylation of Ketones with Primary Alcohols4.3 Transfer Hydrogenation of Ketones5 Conclusion

Dinuclear ruthenium(II)-NNN complexes were efficiently assembled by means of coordinatively unsaturated 16-electron mononuclear ruthenium(II)-pyrazolyl-imidazolyl-pyridine complex and 4,4′-linked bipyridine ligands. The diruthenium(II)-NNN complex assembled through 4,4′-(CH2)3-bipyridine exhibited exceptionally high catalytic activity for the transfer hydrogenation (TH) of ketones in refluxing 2-propanol and reached TOF values up to 1.4 × 107 h–1, demonstrating a remarkable cooperative effect from the ruthenium(II)-NNN functionalities.

A simple and efficient method for determination of the yield, enantiomeric/diasteriomeric excess (ee/de), and absolute configuration of crude chiral diols without the need of work-up and product isolation in a high throughput setting is described. This approach utilizes a self-assembled iminoboronate ester formed as a product by dynamic covalent self-assembly of a chiral diol with an enantiopure fluorescent amine such as tryptophan methyl ester or tryptophanol and 2-formylphenylboronic acid. The resulting diastereomeric boronates display different photophysical properties and allow for fluorescence-based ee determination of molecules containing a 1,2- or 1,3-diol moiety. This method has been utilized for the screening of ee in a number of chiral diols including atorvastatin, a statin used for the treatment of hypercholesterolemia. Noyori asymmetric hydrogenation of benzil was performed in a highly parallel fashion with errors

Double asymmetric hydrogenation of linear β,β-disubstituted α,β-unsaturated ketones catalyzed by the DM-SEGPHOS/DMAPEN/RuII complex with t-C4H9OK afforded the γ-substituted secondary alcohols in high diastereo- and enantioselectivities. Some mechanistic experiments suggested that two different reactive species, type (I) and (II), were reversibly formed in this catalytic system: Type (I) with the diamine ligand DMAPEN enantioselectively hydrogenated the enones into the chiral allylic alcohols, and type (II) without the diamine ligand diastereoselectively hydrogenated the allylic alcohols into the γ-substituted secondary alcohols. This dual catalysis protocol was successfully applied to the reaction of a variety of aliphatic- and aromatic-substituted enone substrates.

Herein, it is presented a novel catalytic system for the continuous-flow chemoselective hydrogenation of α,β – unsaturated aldehydes used in the production of high-value cosmetics and pharmaceuticals precursors. The reaction was catalyzed by nano-nickel particles grafted on polymeric support, synthesized via a simple, adaptable and green methodology. The system was highly active and very selective to C C bond saturation.

The Trost ligand, (1S,2S)-1,2-diaminocyclohexane-N,N′-bis(2′-diphenylphosphinobenzoyl) (L), is reported for the first time as a ligand for the asymmetric hydrogenation (AH) of ketones. Ligand (S,S)-L was screened in the presence of several metal salts and was found to form active catalysts if combined with ruthenium sources in the presence of hydrogen and a base. Reaction optimization was performed by screening different Ru sources, solvents, and bases. Under the optimized conditions, the complex formed by the combination of (S,S)-L with RuCl3(H2O)x in the presence of Na2CO3 was able to promote the AH of several ketones at room temperature in good yields with up to 96 % ee. The reaction kinetics measured under the optimized conditions revealed the presence of a long induction period, during which the initially formed Ru species was transformed into the catalytically active complex by reaction with hydrogen. Remarkably, a ketone that is a precursor of the antiemetic drug aprepitant was hydrogenated in excellent yield with a good ee value.

Base-metal catalysis, especially with non-noble-metal pincer-type catalysts, is increasingly used in organic synthesis and thus becoming more and more important for organometallic chemistry. After ruthenium-, iridium- and iron-based pincer-type complexes became established as state-of-the-art catalysts for (de)hydrogenation reactions in the past decade, manganese complexes have most recently been successfully applied in related transformations. Specifically, this microreview covers their recent progress in (de)hydrogenation and transfer (de)hydrogenation as well as in C–C and C–X bond-forming reactions.

A changeable ligand, which involves in activation of a catalyst or assists a reaction, draws an increasing attention, in contrast to a classical ligand as spectator. Proton-responsive catalysts, which are capable of undergoing changes of properties on gaining/losing one or more protons, provides interesting features as follows: (i) catalyst activation by electronic effect, (ii) pH-tuning of water-solubility, and (iii) second-coordination-sphere interaction. On the basis of this catalyst design concept, we developed several highly efficient proton-responsive catalysts for CO2 hydrogenation as H2 storage, formic acid (FA) dehydrogenation as H2 production, and transfer hydrogenation. The transformable ligands of proton-responsive catalysts in promoting effective catalysis have aroused our interest. In this account, we summarize our efforts for the development and application of proton-responsive catalysts. Specifically, the important role of pH-dependent proton-responsive complexes will be discussed.

We describe a tandem process to generate active Ru nanoparticles (≈7 nm) immobilised in situ on carbon from an organometallic precursor and formic acid to afford the hydrogenation of a wide range of arenes and heteroarenes in yields up to 72 % with high conversions and selectivities for the desired products. The hydrogenation of several substrates analogous to lignin-derived fragments to the corresponding alicyclic products was also achieved. Our experimental investigations evidenced that the observed enhanced activity for arene hydrogenation was driven by the unique structural advantages of the organometallic precursor to activate formic acid, in which the presence of a nitrogen ligand is crucial to achieve a high catalytic activity. TEM analysis revealed the formation of Ru0 nanoparticles, and Hg0 poisoning experiments support the heterogeneous nature of the active catalyst.

Two different iridium catalyst systems, generated from the ruthenocene-based phosphine-oxazoline ligand tBu-mono-RuPHOX or the diphosphine ligand BINAP, were developed for the asymmetric hydrogenation of 5,6-dihydropyrazin-2(1H)-ones, affording chiral piperazin-2-ones in good yields and with moderate to good ees. Different catalytic behaviors for the hydrogenation of these types of substrate were observed with these two catalyst systems. Our tBu-mono-RuPHOX ligand, which bears a ruthenocene scaffold with planar chirality, was found to be the best ligand for the [Ir(L)(COD)]BArF catalyst system, affording the desired products with up to 94% ee.

The hydrogenation of alkenes catalyzed by disilametallacyclic carbonyl complexes of iron, ruthenium or osmium was studied experimentally and theoretically. The disilaruthenacycle 2 with two CO ligands in the trans-configuration was prepared, characterized, and its ability to catalyze hydrogenation was studied. Similar to the corresponding iron analogue 1 in which the CO ligands are in the cis-configuration, 2 contains a H2MSi4 core with Si⋯H⋯Si SISHA (secondary interaction of silicon and hydrogen atoms) and catalyzed the hydrogenation of several alkenes under mild conditions. DFT calculations of 1 and 2 with cis- and trans-CO configurations (cis-1, trans-1, cis-2 and trans-2) revealed that the mechanism of ethylene hydrogenation comprises three catalytic cycles, and a key step involves the H-H bond of H2 being activated by an M-Si bond through oxidative hydrogen migration. These mechanisms are a variety of σ-CAM (σ-complex-assisted metathesis) mechanisms. Further calculations suggest that these catalytic ...

Herein, we report a catalyst composed of palladium nanoparticles immobilized on polymeric resin for chemoselective hydrogenation reactions under flow conditions. The catalyst exhibits high activity and selectivity towards hydrogenation of C C double bond, as confirmed in the hydrogenation of 2-heptene and 6-methyl-5-hepten-2-one.

New cyclometalated ruthenium(II) complexes of the type [Ru(L)(CO)(EPh3)2] (L = di-anionic CNO- donor of 1-(biphenylazo)naphthol; E = P, As) have been synthesized by the reaction using [RuHCl(CO)(EPh3)3] (E = P, As) with 1-(biphenylazo)naphthol ligand (H2L). The 1-(biphenylazo)naphthol ligand and ruthenium complexes are characterized by analytical, spectral (FT–IR, UV–Vis, 1H NMR and 31P NMR) methods. The molecular structure of ruthenium complex 1 was further confirmed by single crystal X-ray diffraction method. The catalytic efficiency of ruthenium complex 1 was evaluated for the transfer hydrogenation of various ketones to alcohols with excellent conversion up to 99% in the presence of i-PrOH/KOH at 82 °C.

Developing new, efficient catalysts that contain Earth-abundant metals and simple, robust ligands for CO2 hydrogenation is important to create cost-effective processes of CO2 utilization. Inspired by nature, which utilizes an ortho-OH-substituted pyridine motif in Fe-containing hydrogenases, we developed a Mn complex with a simple N-donor ligand, 6,6′-dihydroxy-2,2′-bipyridine, that acts as an efficient catalyst for CO2 hydrogenation. Turnover numbers of 6250 for hydrogenation of CO2 to formate in the presence of DBU were achieved. Moreover, hydrogenation of CO2 to formamide was achieved in the presence of a secondary amine.

The catalytic partial hydrogenation of substituted alkynes to alkenes is a process of high importance in the manufacture of several market chemicals. The present paper shortly reviews the heterogeneous catalytic systems engineered for this reaction under continuous flow and in the liquid phase. The main contributions appeared in the literature from 1997 up to August 2016 are discussed in terms of reactor design. A comparison with batch and industrial processes is provided whenever possible.

Three ruthenium(II) and two iridium(III) N-heterocyclic carbene (NHC) complexes functionalized with sulfonates are compared with respect to their activity and selectivity for the transfer hydrogenation of imines, aldehydes, ketones, and olefins using neat glycerol as hydrogen donor and solvent. Four of the five catalysts likely proceed through a monohydride mechanism and are more active for transfer hydrogenation of imines than aldehydes, ketones, and olefins. The fifth catalyst likely proceeds through a dihydride mechanism and is found to be more active for carbonyls than imines and olefins. Lactic acid is observed as the only detectable byproduct from glycerol. Quantitative poisoning experiments with 1,10-phenanthroline suggest that the predominant catalytically active species is a ligated homogeneous complex with weak binding to the poison. The potential for catalyst recycling is explored: the ruthenium NHC catalysts with chelating ligands are found to be more robust and recyclable relative to the irid...