cas 464-07-3, 3,3-DIMETHYL-2-BUTANOL | Articles data

Articles about 464-07-3Total 100 be found

Article title
Article abstract
Author
Journal number and time
Download

Biomimetic ketone reduction by disulfide radical anion
The conversion of ribonucleosides to 2′-deoxyribonucleosides is catalyzed by ribonucleoside reductase enzymes in nature. One of the key steps in this complex radical mechanism is the reduction of the 3′-ketodeoxynucleotide by a pair of cysteine residues, providing the electrons via a disulfide radical anion (RSSR??) in the active site of the enzyme. In the present study, the bioinspired conversion of ketones to corresponding alcohols was achieved by the intermediacy of disulfide radical anion of cysteine (CysSSCys)?? in water. High concentration of cysteine and pH 10.6 are necessary for high-yielding reactions. The photoinitiated radical chain reaction includes the one-electron reduction of carbonyl moiety by disulfide radical anion, protonation of the resulting ketyl radical anion by water, and H-atom abstraction from CysSH. The (CysSSCys)?? transient species generated by ionizing radiation in aqueous solutions allowed the measurement of kinetic data with ketones by pulse radiolysis. By measuring the rate of the decay of (CysSSCys)?? at λmax = 420 nm at various concentrations of ketones, we found the rate constants of three cyclic ketones to be in the range of 104–105 M?1s?1 at ~22?C.
Barata-Vallejo, Sebastian,Bobrowski, Krzysztof,Chatgilialoglu, Chryssostomos,Ferreri, Carla,Marciniak, Bronislaw,Skotnicki, Konrad
(2021/09/13)

Highly Active Cooperative Lewis Acid—Ammonium Salt Catalyst for the Enantioselective Hydroboration of Ketones
Enantiopure secondary alcohols are fundamental high-value synthetic building blocks. One of the most attractive ways to get access to this compound class is the catalytic hydroboration. We describe a new concept for this reaction type that allowed for exceptional catalytic turnover numbers (up to 15 400), which were increased by around 1.5–3 orders of magnitude compared to the most active catalysts previously reported. In our concept an aprotic ammonium halide moiety cooperates with an oxophilic Lewis acid within the same catalyst molecule. Control experiments reveal that both catalytic centers are essential for the observed activity. Kinetic, spectroscopic and computational studies show that the hydride transfer is rate limiting and proceeds via a concerted mechanism, in which hydride at Boron is continuously displaced by iodide, reminiscent to an SN2 reaction. The catalyst, which is accessible in high yields in few steps, was found to be stable during catalysis, readily recyclable and could be reused 10 times still efficiently working.
Titze, Marvin,Heitk?mper, Juliane,Junge, Thorsten,K?stner, Johannes,Peters, René
supporting information
p. 5544 - 5553
(2021/02/05)

1,3,4-Oxadiazole-functionalizedα-amino-phosphonates as ligands for the ruthenium-catalyzed reduction of ketones
Threeα-aminophosphonates, namely diethyl[(5-phenyl-1,3,4-oxadiazol-2-ylamino)(4-trifluoromethylphenyl) methyl]phosphonate (3a), diethyl[(5-phenyl-1,3,4-oxadiazol-2-ylamino)(2-methoxyphenyl)methyl]phosphonate (3b) and diethyl[(5-phenyl-1,3,4-oxadiazol-2-ylamino)(4-nitrophenyl)methyl]phosphonate (3c), were synthetizedviathe Pudovik-type reaction between diethyl phosphite and imines, obtained from 5-phenyl-1,2,4-oxadiazol-2-amine and aromatic aldehydes, under microwave irradiation. Compounds3a-cunderwent complexation with a ruthenium(ii) precursor, selectively at the more basic nitrogen atom of the oxadiazole ring, leading to the corresponding ruthenium complexes4a-cof the formula [RuCl2(L)(p-cymene)] (L= α-aminophosphonates3a-c). Complexes4a-cproved to be efficient catalysts for the transfer hydrogenation of ketones to alcohols. All new compounds were fully characterised by elemental analysis, infrared, mass and NMR spectroscopy. An X-ray structure of the α-aminophosphonate3bwas obtained and revealed the presence, in the solid state, of an infinite chain of3bunits supramolecularly interlinked. Two X-ray diffraction studies carried out on ruthenium complexes confirm the specific coordination of the electron-enricher nitrogen atom of the oxadiazole ring.
Hkiri, Shaima,Gourlaouen, Christophe,Touil, Soufiane,Samarat, Ali,Sémeril, David
p. 11327 - 11335
(2021/07/02)

Erbium-Catalyzed Regioselective Isomerization-Cobalt-Catalyzed Transfer Hydrogenation Sequence for the Synthesis of Anti-Markovnikov Alcohols from Epoxides under Mild Conditions
Herein, we report an efficient isomerization-transfer hydrogenation reaction sequence based on a cobalt pincer catalyst (1 mol %), which allows the synthesis of a series of anti-Markovnikov alcohols from terminal and internal epoxides under mild reaction conditions (≤55 °C, 8 h) at low catalyst loading. The reaction proceeds by Lewis acid (3 mol % Er(OTf)3)-catalyzed epoxide isomerization and subsequent cobalt-catalyzed transfer hydrogenation using ammonia borane as the hydrogen source. The general applicability of this methodology is highlighted by the synthesis of 43 alcohols from epoxides. A variety of terminal (23 examples) and 1,2-disubstituted internal epoxides (14 examples) bearing different functional groups are converted to the desired anti-Markovnikov alcohols in excellent selectivity and yields of up to 98%. For selected examples, it is shown that the reaction can be performed on a preparative scale up to 50 mmol. Notably, the isomerization step proceeds via the most stable carbocation. Thus, the regiochemistry is controlled by stereoelectronic effects. As a result, in some cases, rearrangement of the carbon framework is observed when tri-and tetra-substituted epoxides (6 examples) are converted. A variety of functional groups are tolerated under the reaction conditions even though aldehydes and ketones are also reduced to the respective alcohols under the reaction conditions. Mechanistic studies and control experiments were used to investigate the role of the Lewis acid in the reaction. Besides acting as the catalyst for the epoxide isomerization, the Lewis acid was found to facilitate the dehydrogenation of the hydrogen donor, which enhances the rate of the transfer hydrogenation step. These experiments additionally indicate the direct transfer of hydrogen from the amine borane in the reduction step.
Liu, Xin,Longwitz, Lars,Spiegelberg, Brian,T?njes, Jan,Beweries, Torsten,Werner, Thomas
p. 13659 - 13667
(2020/11/30)

Ligand Effect in Alkali-Metal-Catalyzed Transfer Hydrogenation of Ketones
This work unveils the reactivity patterns, as well as ligand and additive effect on alkali-metal-base-catalyzed transfer hydrogenation of ketones. Crucially to this reactivity is the presence of a Lewis acid (alkali cation), as opposed to a simple base effect. With aryl ketones, the observed reactivity order is Na+>Li+>K+, whereas for aliphatic substrates it follows the expected Lewis acidity, Li+>Na+>K+. Importantly, the reactivity pattern can be drastically changed by adding ligands and additives. Kinetic, labelling, and competition experiments as well as DFT calculations suggested that the reaction proceeds through a concerted direct hydride-transfer mechanism, originally suggested by Woodward. The lithium cation was found to be intrinsically more active than heavier congeners, but in the case of aryl ketones a decrease in reaction rate was observed at ≈40 percent conversion with lithium cations. Noncovalent-interaction analysis revealed that this deceleration effect originated from specific noncovalent interactions between the aryl moiety of 1-phenylethanol and the carbonyl group of acetophenone, which stabilize the product in the coordination sphere of lithium and thus poison the catalyst. The ligand/additive effect is a complicated phenomenon that includes a combination of several factors, such as the decrease of activation energy by ligation (confirmed by distortion/interaction calculations of N,N,N’,N’-tetramethylethylenediamine, TMEDA) and the change in relative stabilization of reagents and substrates in the solution and the coordination sphere of the metal. Finally, we observed that lithium-base-catalyzed transfer hydrogenation can be further facilitated by the addition of an inexpensive and benign reagent, LiCl, which likely operates by re-initiating the reaction on a new lithium center.
Alshakova, Iryna D.,Dudding, Travis,Foy, Hayden C.,Nikonov, Georgii I.
supporting information

(2019/08/21)

Flat and Efficient H CNN and CNN Pincer Ruthenium Catalysts for Carbonyl Compound Reduction
The bidentate HCNN dicarbonyl ruthenium complexes trans,cis-[RuCl2(HCNN)(CO)2] (1-3) and trans,cis-[RuCl2(ampy)(CO)2] (1a) were prepared by reaction of [RuCl2(CO)2]n with 1-[6-(4′-methylphenyl)pyridin-2-yl]methanamine, benzo[h]quinoline (HCNN), and 2-(aminomethyl)pyridine (ampy) ligands. Alternatively, the derivatives 1-3 were obtained from the reaction of RuCl3 hydrate with HCO2H and HCNN. The pincer CNN cis-[RuCl(CNN)(CO)2] (4) was isolated from 1 by reaction with NEt3. The monocarbonyl complexes trans-[RuCl2(HCNN)(PPh3)(CO)] (5-7) were synthesized from [RuCl2(dmf)(PPh3)2(CO)] and HCNN ligands, while the diacetate trans-[Ru(OAc)2(HCNN)(PPh3)(CO)] (8) was obtained from [Ru(OAc)2(PPh3)2(CO)]. Carbonylation of cis-[RuCl(CNN)(PPh3)2] with CO afforded the pincer derivatives [RuCl(CNN)(PPh3)(CO)] (9-11). Treatment of 9 with Na[BArf]4 and PPh3 gave the cationic complex trans-[Ru(CNN)(PPh3)2(CO)][BArf4] (12). The dicarbonyl derivatives 1-4, in the presence of PPh3 or PCy3, and the monocarbonyl complexes 5-12 catalyzed the transfer hydrogenation (TH) of acetophenone (a) in 2-propanol at reflux (S/C = 1000-100000 and TOF up to 100000 h-1). Compounds 1-3, with PCy3, and 6 and 8-10 were proven to catalyze the TH of carbonyl compounds, including α,β-unsaturated aldehydes and bulky ketones (S/C and TOF up to 10000 and 100000 h-1, respectively). The derivatives 1-3 with PCy3 and 5 and 6 catalyzed the hydrogenation (HY) of a (H2, 30 bar) at 70 °C (S/C = 2000-10000). Complex 5 was active in the HY of diaryl ketones and aryl methyl ketones, leading to complete conversion at S/C = 10000.
Giboulot, Steven,Baldino, Salvatore,Ballico, Maurizio,Figliolia, Rosario,P?thig, Alexander,Zhang, Shuanming,Zuccaccia, Daniele,Baratta, Walter
p. 1127 - 1142
(2019/03/14)

Hydrosilylation of carbonyl and carboxyl groups catalysed by Mn(i) complexes bearing triazole ligands
Manganese(i) complexes bearing triazole ligands are reported as catalysts for the hydrosilylation of carbonyl and carboxyl compounds. The desired reaction proceeds readily at 80 °C within 3 hours at catalyst loadings as low as 0.25 to 1 mol%. Hence, good to excellent yields of alcohols could be obtained for a wide range of substrates including ketones, esters, and carboxylic acids illustrating the versatility of the metal/ligand combination.
Martínez-Ferraté, Oriol,Chatterjee, Basujit,Werlé, Christophe,Leitner, Walter
p. 6370 - 6378
(2019/11/20)

Magnesium Exchanged Zirconium Metal-Organic Frameworks with Improved Detoxification Properties of Nerve Agents
UiO-66, MOF-808 and NU-1000 metal-organic frameworks exhibit a differentiated reactivity toward [Mg(OMe)2(MeOH)2]4 related to their pore accessibility. Microporous UiO-66 remains unchanged while mesoporous MOF-808 and hierarchical micro/mesoporous NU-1000 materials yield doped systems containing exposed MgZr5O2(OH)6 clusters in the mesoporous cavities. This modification is responsible for a remarkable enhancement of the catalytic activity toward the hydrolytic degradation of P-F and P-S bonds of toxic nerve agents, at room temperature, in unbuffered aqueous solutions.
Gil-San-Millan, Rodrigo,López-Maya, Elena,Platero-Prats, Ana E.,Torres-Pérez, Virginia,Delgado, Pedro,Augustyniak, Adam W.,Kim, Min Kun,Lee, Hae Wan,Ryu, Sam Gon,Navarro, Jorge A. R.
supporting information
p. 11801 - 11805
(2019/08/28)

“Inverse” Frustrated Lewis Pairs: An Inverse FLP Approach to the Catalytic Metal Free Hydrogenation of Ketones
For the first time have boron-containing weak Lewis acids been demonstrated to be active components of Frustrated Lewis Pair (FLP) catalysts in the hydrogenation of ketones to alcohols. Combining the organosuperbase (pyrr)3P=NtBu with the Lewis acid 9-(4-CF3-C6H4)-BBN generated an “inverse” FLP catalyst capable of hydrogenating a range of aliphatic and aromatic ketones including N-, O- and S-functionalized substrates and bio-mass derived ethyl levulinate. Initial computational and experimental studies indicate the mechanism of catalytic hydrogenation with “inverse” FLPs to be different from conventional FLP catalysts that contain strong Lewis acids such as B(C6F5)3.
Mummadi, Suresh,Brar, Amandeep,Wang, Guoqiang,Kenefake, Dustin,Diaz, Rony,Unruh, Daniel K.,Li, Shuhua,Krempner, Clemens
supporting information
p. 16526 - 16531
(2018/10/20)

FLP-Catalyzed Transfer Hydrogenation of Silyl Enol Ethers
Herein we report the first catalytic transfer hydrogenation of silyl enol ethers. This metal free approach employs tris(pentafluorophenyl)borane and 2,2,6,6-tetramethylpiperidine (TMP) as a commercially available FLP catalyst system and naturally occurring γ-terpinene as a dihydrogen surrogate. A variety of silyl enol ethers undergo efficient hydrogenation, with the reduced products isolated in excellent yields (29 examples, 82 % average yield).
Khan, Imtiaz,Reed-Berendt, Benjamin G.,Melen, Rebecca L.,Morrill, Louis C.
p. 12356 - 12359
(2018/09/18)

Aminotriazole Mn(I) Complexes as Effective Catalysts for Transfer Hydrogenation of Ketones
A catalytic system based on complexes comprising abundant and cheap manganese together with readily available aminotriazole ligands is reported. The new Mn(I) complexes are catalytically competent in transfer hydrogenation of ketones with 2-propanol as hydrogen source. The reaction proceeds under mild conditions at 80 °C for 20 h with 3 % of catalyst loading using either KOtBu or NaOH as base. Good to excellent yields were obtained for a wide substrate scope with broad functional group tolerance. The obtained results by varying the substitution pattern of the ligand are consistent with an out-sphere mechanism for the H-transfer.
Martínez-Ferraté, Oriol,Werlé, Christophe,Franciò, Giancarlo,Leitner, Walter
p. 4514 - 4518
(2018/10/20)

Interplay between Substrate and Proton Donor Coordination in Reductions of Carbonyls by SmI2-Water Through Proton-Coupled Electron-Transfer
The reduction of a carbonyl by SmI2-water is the first step in a range of reactions of synthetic importance. Although the reduction is often proposed to proceed through an initial stepwise electron-transfer-proton-transfer (ET-PT), recent work has shown that carbonyls and related functional groups are likely reduced though proton-coupled electron-transfer (PCET). In the present work, the reduction of an activated ester, aldehyde, a linear and cyclic ketone, and related sterically demanding carbonyls by SmI2-H2O was examined through a series of mechanistic experiments. Kinetic studies demonstrate that all substrates exhibit significant increases in the rate of reduction by SmI2 as [H2O] is increased. Under identical conditions, ketones and an aldehyde containing a methyl adjacent to the carbonyl are reduced slower than an unsubstituted variant by an order of magnitude, demonstrating the importance of substrate coordination. In the case of unactivated substrates, rates of reduction show excellent correlation with the calculated bond dissociation free energy of the O-H bond of the intermediate ketyl and the calculated free energy of intermediate ketyl radical anions derived from unhindered substrates: findings consistent with concerted PCET. Activated esters derived from methylbenzoate are likely reduced through stepwise or asynchronous PCET. Overall, this work demonstrates that the combination of the coordination of substrate and water to Sm(II) provides a configuration uniquely suited to a coupled electron- and proton-transfer process.
Chciuk, Tesia V.,Anderson, William R.,Flowers, Robert A.
supporting information
p. 15342 - 15352
(2018/11/30)

Failure and Redemption of Statistical and Nonstatistical Rate Theories in the Hydroboration of Alkenes
Our previous work found that canonical forms of transition state theory incorrectly predict the regioselectivity of the hydroboration of propene with BH3 in solution. In response, it has been suggested that alternative statistical and nonstatistical rate theories can adequately account for the selectivity. This paper uses a combination of experimental and theoretical studies to critically evaluate the ability of these rate theories, as well as dynamic trajectories and newly developed localized statistical models, to predict quantitative selectivities and qualitative trends in hydroborations on a broader scale. The hydroboration of a series of terminally substituted alkenes with BH3 was examined experimentally, and a classically unexpected trend is that the selectivity increases as the alkyl chain is lengthened far from the reactive centers. Conventional and variational transition state theories can predict neither the selectivities nor the trends. The canonical competitive nonstatistical model makes somewhat better predictions for some alkenes but fails to predict trends, and it performs poorly with an alkene chosen to test a specific prediction of the model. Added nonstatistical corrections to this model make the predictions worse. Parametrized Rice-Ramsperger-Kassel-Marcus (RRKM)-master equation calculations correctly predict the direction of the trend in selectivity versus alkene size but overpredict its magnitude, and the selectivity with large alkenes remains unpredictable with any parametrization. Trajectory studies in explicit solvent can predict selectivities without parametrization but are impractical for predicting small changes in selectivity. From a lifetime and energy analysis of the trajectories, "localized RRKM-ME" and "competitive localized noncanonical" rate models are suggested as steps toward a general model. These provide the best predictions of the experimental observations and insight into the selectivities.
Bailey, Johnathan O.,Singleton, Daniel A.
supporting information
p. 15710 - 15723
(2017/11/14)

Catalytic carbonyl hydrosilylations: Via a titanocene borohydride-PMHS reagent system
Reduction of a wide range of aldehydes and ketones with catalytic amounts of titanocene borohydride in concert with a stoichiometric poly(methylhydrosiloxane) (PMHS) reductant is reported. Preliminary mechanistic studies demonstrate that the reaction is mediated by a reactive titanocene(iii) complex, whose oxidation state remains constant throughout the reaction.
Fianu, Godfred D.,Schipper, Kyle C.,Flowers, Robert A.
p. 3469 - 3473
(2017/08/21)

Hydroxyl group effect in novel NNN type pyridine based ruthenium (II) complex for the transfer hydrogenation of ketones
The new NNN type pyridine ligands were prepared by using low cost and readily available starting materials and metalated with RuCl2(PPh3)3 to obtain ruthenium(II) complexes. All structures were illuminated by NMR, HRMS, and FT-IR spectroscopy. The complexes exhibited good catalytic activity in transfer hydrogen reaction of ketones and it was found that a hydroxyl group on β-position of the pyridine ring had a dramatic effect on the catalyst efficiency.
Sahin, Irfan,Emir, Sedat,Ispir, Esin,Karakaya, Idris,Gumus, Selcuk,Ulusoy, Mahmut,Karabuga, Semistan
p. 30 - 33
(2016/07/21)

Preparation of Pincer 4-Functionalized 2-Aminomethylbenzo[h]quinoline Ruthenium Catalysts for Ketone Reduction
Reaction of 1-naphthylamine with ethyl benzoylacetate gives the corresponding benzoyl acetamide derivative 1, which undergoes cyclization to 4-phenylbenzo[h]quinolin-2(1H)-one (2) in the presence of H2SO4. Bromination with POBr3, followed by reaction with n-BuLi and DMF, gives 4-phenylbenzo[h]quinoline-2-carbaldehyde (4), which is converted to the corresponding oxime hydrochloride 5 with NH2OH·HCl. Hydrogenation of 5 catalyzed by 10% Pd/C (type 338) leads to 4-phenyl-2-aminomethylbenzo[h]quinoline hydrochloride (HCNNPh·HCl, 6) isolated in high yield. Similarly, the 4-methyl-2-aminomethylbenzo[h]quinoline derivative (HCNNMe·HCl, 12) is prepared starting from 1-naphthylamine and 2,2,6-trimethyl-4H-1,3-dioxin-4-one, following the route for 6. Reaction of RuCl2(PPh3)3 with a diphosphine (PP), the HCl salt 6, and NEt3 in 2-propanol leads to the pincer complexes RuCl(CNNPh)(PP) (PP = Ph2P(CH2)3PPh2, 13; Ph2P(CH2)4PPh2, 14; 1,1′-bis(diphenylphosphino)ferrocene, 15). The methyl derivatives RuCl(CNNMe)(PP) (PP = Ph2P(CH2)3PPh2, 16; Ph2P(CH2)4PPh2, 17; 1,1′-bis(diphenylphosphino)ferrocene, 18) are obtained in a similar way using 12 in place of 6. Treatment of [RuCl2(p-cymene)]2 with rac-BINAP, 6, and NEt3 affords RuCl(CNNPh)(BINAP) (19), isolated as a mixture of two diastereoisomers (3:4 molar ratio). The chiral RuCl(CNNPh)[(S,R)-JOSIPHOS] (20) is obtained as a single isomer from [RuCl2(p-cymene)]2, (S,R)-JOSIPHOS, and 6. Complexes 13-20 efficiently catalyze the transfer hydrogenation of acetophenone in 2-propanol at reflux in the presence of NaOiPr (2 mol%) with S/C = 5000-20-000 and at high rate (TOF up to 6.7 × 103 min-1). With complexes 13, 15, 17, and 18 several ketones of commercial-grade purity have been reduced to alcohols, including the bulky RCO(tBu) (R = Me, Ph) substrates. With 20 acetophenone is reduced to (S)-1-phenylethanol with 85% ee. The pincer complexes 13-15 and 18 are also found highly active in the hydrogenation of ketones at 40 °C with an S/C = 10-000, under 5 bar of dihydrogen in methanol and in the presence of 2 mol % of a base (NaOH, KOH, NaOMe).
Facchetti, Sarah,Jurcik, Vaclav,Baldino, Salvatore,Giboulot, Steven,Nedden, Hans Günter,Zanotti-Gerosa, Antonio,Blackaby, Andrew,Bryan, Richard,Boogaard, Adrian,McLaren, David B.,Moya, Eduardo,Reynolds, Steven,Sandham, Karl S.,Martinuzzi, Paolo,Baratta, Walter
p. 277 - 287
(2016/02/05)

Synthesis, characterization and reactivity of iron- and cobalt-pincer complexes
The tBuPONOP (2,6-bis(di-tert-butyl-phosphinito)pyridine) complexes of iron and cobalt, (tBuPONOP)FeCl2 (1) and (tBuPONOP)CoCl2 (2)) have been prepared. Both complexes are paramagnetic and the solid-state structures of 1 and 2 were determined by single crystal X-ray diffraction studies. Analogous Fe and Co complexes of the tBuPNP (2,6-bis(di-tert-butyl-phosphinomethyl)pyridine) ligand (3 and 4, respectively) were prepared to allow comparison between the closely related pincer ligands in the hydrosilylation of carbonyl moieties. All four complexes were found to be catalytically active when treated with NaBEt3H, which was assumed to generate a metal-hydride species in-situ.
Smith, Ashleigh D.,Saini, Anu,Singer, Laci M.,Phadke, Neha,Findlater, Michael
p. 286 - 291
(2016/07/06)

Development of an axially chiral sp3P/sp3NH/sp2N-combined linear tridentate ligand - Fac-selective formation of Ru(II) complexes and application to ketone hydrogenation
A newly developed chiral linear tridentate ligand, R-PN(H)N (R=H or Ph), possesses Ph2P and PyCH2NH groups at C(2) and C(2′) positions of the 1,1′-binaphthyl skeleton without or with a C(3)-Ph substituent. The steric effect of C(3)-Ph and the electronic effect of the DMSO co-ligand realize the facial selective generation of fac-RuCl2(Ph-PN(H)N)(dmso) and fac-[Ru(H-PN(H)N)(dmso)3](BF4)2, respectively. Both an H-Ru?sp3N-H reaction site responsible for the donor-acceptor bifunctional catalyst (DACat) and a fence/plane chiral context were constructed by means of the following advantageous points: i) the sp3P, sp3N, and sp2N ligating atoms have different electronic properties; ii) DMSO trans to sp3N strongly coordinates to Ru and is fixed by a PyC(6)H?O=S hydrogen bond; and iii) the single NH function simplifies the DACat reaction site. The synergistic effect has led to success in the asymmetric hydrogenation of sterically demanding ketones. Structural characteristics of first-row transition metal complexes of R-PN(H)N have been also investigated.
Yamamura, Tomoya,Nakane, Satoshi,Nomura, Yuko,Tanaka, Shinji,Kitamura, Masato
supporting information
p. 3781 - 3789
(2016/06/06)

BENZO[H]QUINOLINE LIGANDS AND COMPLEXES THEREOF
The present invention provides substituted tridentate benzo[h]quinoline ligands and complexes thereof. The invention also provides the preparation of the ligands and the respective complexes, as well as to processes for using the complexes in catalytic reactions.
-
Page/Page column 72-73

(2016/12/22)

Versatile Catalytic Hydrogenation Using A Simple Tin(IV) Lewis Acid
Despite the rapid development of frustrated Lewis pair (FLP) chemistry over the last ten years, its application in catalytic hydrogenations remains dependent on a narrow family of structurally similar early main-group Lewis acids (LAs), inevitably placing limitations on reactivity, sensitivity and substrate scope. Herein we describe the FLP-mediated H2activation and catalytic hydrogenation activity of the alternative LA iPr3SnOTf, which acts as a surrogate for the trialkylstannylium ion iPr3Sn+, and is rapidly and easily prepared from simple, inexpensive starting materials. This highly thermally robust LA is found to be competent in the hydrogenation of a number of different unsaturated functional groups (which is unique to date for main-group FLP LAs not based on boron), and also displays a remarkable tolerance to moisture.
Scott, Daniel J.,Phillips, Nicholas A.,Sapsford, Joshua S.,Deacy, Arron C.,Fuchter, Matthew J.,Ashley, Andrew E.
supporting information
p. 14738 - 14742
(2016/11/23)

Transfer hydrogenation of unsaturated bonds in the absence of base additives catalyzed by a cobalt-based heterogeneous catalyst
A novel non-noble Co@C-N catalytic system has been developed for catalytic transfer hydrogenation reactions. Co@C-N was found to be highly active and selective in the hydrogenation of a variety of unsaturated bonds with isopropanol in the absence of base additives.
Long, Jilan,Zhou, Ying,Li, Yingwei
supporting information
p. 2331 - 2334
(2015/02/05)

Synthesis and reactivity of heteroditopic dicarbene rhodium(i) and iridium(i) complexes bearing chelating 1,2,3-triazolylidene-imidazolylidene ligands
1,2,3-Triazol-5-ylidenes (tzNHC) have become a popular class of NHC ligands in homogeneous catalysis. Herein, we introduce chelate monovalent Rh- and Ir(cod) complexes bearing bidentate ligands that combine this tzNHC and an Arduengo-type NHC motif. The reactivity of these complexes with H2 and CO gas has been investigated, leading to an interesting octahedral [Ir(tzNHC-CH2-NHC)(CO)2(H)2]OTf complex and [M(tzNHC-CH2-NHC)(CO)2]OTf complexes. The carbonyl stretching frequencies of the latter indicate that the ligand has stronger electron-donating properties than classic di-NHC ligands. The square planar rhodium and iridium NHC-tzNHC complexes have been applied in transfer hydrogenation employing isopropyl alcohol as the hydrogen donor, in which they show moderate activity (Ir > Rh) toward a range of ketones as well as for an aldehyde, an imine, and a diene. The new dicarbene complexes proved to be more active for this reaction than the analogues in which the triazolyl moiety coordinates through a nitrogen donor.
Sluijter, Soraya N.,Elsevier, Cornelis J.
p. 6389 - 6397
(2015/02/19)

Organoleptic compound
The present invention is directed to a novel compound, but-2-enoic acid 1,2-dimethyl-butyl ester, and a method of improving, enhancing or modifying a fragrance formulation through the addition of an olfactory acceptable amount of but-2-enoic acid 1,2-dimethyl-butyl ester.
-
Page/Page column 5; 6

(2014/08/06)

Novel Organoleptic Compound
The present invention is directed to a novel compound, but-2-enoic acid 1-ethyl-2-methyl-propyl ester, and a method of improving, enhancing or modifying a fragrance formulation through the addition of an olfactory acceptable amount of but-2-enoic acid 1-ethyl-2-methyl-propyl ester.
-
Paragraph 0028; 0029

(2014/09/03)

A well-defined monomeric aluminum complex as an efficient and general catalyst in the Meerwein-Ponndorf-Verley reduction
The metal-catalyzed Meerwein-Ponndorf-Verley (MPV) reduction allows for the mild and sustainable reduction of aldehydes and ketones but has not found widespread application in organic synthesis due to the high catalyst loading often required to obtain satisfactory yields of the reduced product. We report here on the synthesis and structure of a sterically extremely overloaded siloxide-supported aluminum isopropoxide capable of catalytically reducing a wide range of aldehydes and ketones (52 examples) in excellent yields under mild conditions and with low catalyst loadings. The unseen activity of the developed catalyst system in MPV reductions is due to its unique monomeric nature and the neutral donor isopropanol weakly coordinating to the aluminum center. The present work implies that monomeric aluminum alkoxide catalysts may be attractive alternatives to transition-metalbased systems for the selective reduction of aldehydes and ketones to primary and secondary alcohols.
McNerney, Brian,Whittlesey, Bruce,Cordes, David B.,Krempner, Clemens
supporting information
p. 14959 - 14964
(2015/01/08)

Organoleptic compound
The present invention is directed to a novel compound, but-2-enoic acid 1-ethyl-2-methyl-propyl ester, and a method of improving, enhancing or modifying a fragrance formulation through the addition of an olfactory acceptable amount of but-2-enoic acid 1-ethyl-2-methyl-propyl ester.
-
Page/Page column 6

(2014/07/21)

Asymmetric hydrogenation of tert-alkyl ketones: DMSO effect in unification of stereoisomeric ruthenium complexes
Face off: The ruthenium complexes of a new axially chiral PNNligand (L) are highly efficient in the presence of dimethylsulfoxide (DMSO) for hydrogenation of both functionalized and unfunctionalized tert-alkyl ketones. DMSO is thought to narrow down the many possible complex stereoisomers into a single facial L/Ru complex, thus enhancing the reactivity, selectivity, and productivity. Copyright
Yamamura, Tomoya,Nakatsuka, Hiroshi,Tanaka, Shinji,Kitamura, Masato
supporting information
p. 9313 - 9315
(2013/09/12)

Highly enantioselective hydrogenation of 1-alkylvinyl benzoates: A simple, nonenzymatic access to chiral 2-alkanols
Going chiral! Highly enantioselective catalytic hydrogenations of enol esters 1 by using a Rh catalyst bearing a P?￡?OP ligand are described (see scheme; NBD=norbornadiene). The catalytic system has a broad scope and allows the preparation of a wide range of chiral esters 2 bearing diverse alkyls or a benzyl group with high enantioselectivities. These esters can easily be converted in highly enantioenriched 2-alkanols. Copyright
Kleman, Patryk,González-Liste, Pedro J.,García-Garrido, Sergio E.,Cadierno, Victorio,Pizzano, Antonio
p. 16209 - 16212
(2013/12/04)

Ruthenium-catalyzed α-(hetero)arylation of saturated cyclic amines: Reaction scope and mechanism
Transition-metal-catalyzed sp3 C-H activation has emerged as a powerful approach to functionalize saturated cyclic amines. Our group recently disclosed a direct catalytic arylation reaction of piperidines at the α position to the nitrogen atom. 1-(Pyridin-2-yl)piperidine could be smoothly α-arylated if treated with an arylboronic ester in the presence of a catalytic amount of [Ru3(CO)12] and one equivalent of 3-ethyl-3-pentanol. A systematic study on the substrate and reagent scope of this transformation is disclosed in this paper. The effect of substitution on both the piperidine ring and the arylboronic ester has been investigated. Smaller (pyrrolidine) and larger (azepane) saturated ring systems, as well as benzoannulated derivatives, were found to be compatible substrates with the α-arylation protocol. The successful use of a variety of heteroarylboronic esters as coupling partners further proved the power of this direct functionalization method. Mechanistic studies have allowed for a better understanding of the catalytic cycle of this remarkable transformation featuring an unprecedented direct transmetalation on a RuII-H species. Copyright
Peschiulli, Aldo,Smout, Veerle,Storr, Thomas E.,Mitchell, Emily A.,Elias, Zdenek,Herrebout, Wouter,Berthelot, Didier,Meerpoel, Lieven,Maes, Bert U. W.
p. 10378 - 10387
(2013/09/02)

Bifunctional rhenium complexes for the catalytic transfer-hydrogenation reactions of ketones and imines
The silyloxycyclopentadienyl hydride complexes [Re(H)(NO)(PR 3)(C5H4OSiMe2tBu)] (R=iPr (3a), Cy (3b)) were obtained by the reaction of [Re(H)(Br)(NO)(PR3) 2] (R=iPr, Cy) with Li[C5H4OSiMe 2tBu]. The ligand-metal bifunctional rhenium catalysts [Re(H)(NO)(PR3)(C5H4OH)] (R=iPr (5a), Cy (5b)) were prepared from compounds 3a and 3b by silyl deprotection with TBAF and subsequent acidification of the intermediate salts [Re(H)(NO)(PR 3)(C5H4O)][NBu4] (R=iPr (4a), Cy (4b)) with NH4Br. In nonpolar solvents, compounds 5a and 5b formed an equilibrium with the isomerized trans-dihydride cyclopentadienone species [Re(H)2(NO)(PR3)(C5H4O)] (6a,b). Deuterium-labeling studies of compounds 5a and 5b with D2 and D 2O showed H/D exchange at the HRe and HO positions. Compounds 5a and 5b were active catalysts in the transfer hydrogenation reactions of ketones and imines with 2-propanol as both the solvent and H2 source. The mechanism of the transfer hydrogenation and isomerization reactions was supported by DFT calculations, which suggested a secondary-coordination-sphere mechanism for the transfer hydrogenation of ketones. The Re-al deal: Bifunctional rhenium complexes [Re(H)(NO)(PR 3)(C5H4OH)] (R=Cy, iPr) of Shvo-type were prepared and used as catalysts for the transfer hydrogenation of ketones and imines. TOFs up to 1164 h-1 were obtained for ketones and up to 79 h-1 for imines. DFT calculations suggested a secondary-coordination- sphere mechanism for the transfer hydrogenation of ketones.
Landwehr, Anne,Dudle, Balz,Fox, Thomas,Blacque, Olivier,Berke, Heinz
experimental part
p. 5701 - 5714
(2012/06/18)

HYDROGENATION OF ESTERS OR CARBONYL GROUPS WITH TETRADENTATE AMINO/IMINO-THIOETHER BASED RUTHENIUM COMPLEXES
The present invention relates to the field of catalytic hydrogenation and, more particularly, to the use of specific ruthenium catalysts, or pre-catalysts, in hydrogenation processes for the reduction of ketones and/or aldehydes into the corresponding alcohol respectively. Said catalysts are ruthenium complexes comprising a tetradentate ligand (L4) coordinating the ruthenium with: - two nitrogen atoms, each in the form of a primary or secondary amine (i.e. a NH2 or NH group) or N-alkyl imine functional groups (i.e. a C=N group), and - two sulfur atoms, each in the form of thioether functional groups.
-
Page/Page column 21-22

(2012/07/13)

Transfer hydrogenation with a ferrocene diamide ruthenium complex
The use of a 1,1′-ferrocenediamide ruthenium complex as a mediator for base-free transfer hydrogenation is reported. Ketones were transformed to their respective alcohols at room temperature in 36-99% conversions with turnover frequencies up to 339 h-1.
Elliott, Andrew G.,Green, Aaron G.,Diaconescu, Paula L.
experimental part
p. 7852 - 7854
(2012/08/28)

Selective reductions of the carbonyl compounds and aryl halides with Ni-Al alloy in aqueous alkali medium
The carbonyl compounds and the aryl halides are efficiently reduced by Ni-Al alloy powder, in aqueous alkali medium, with or without organic solvents. The relative reactivities in a series of structurally selected reducible compounds showed a sequence of reactivity in agreement with the mechanism involving a direct electron transfer from aluminum to the organic phase. In some cases an important change in reactivity with respect to conversion of the reducing reagent was notified. Most probably this complicated variability is the result of the changes in composition and morphology of the reacting Ni-Al alloy.
Suceveanu, Mirela,Raicopol, Matei,Enache, Raluca,Finaru, Adriana,Rosca, Sorin I.
experimental part
p. 690 - 695
(2012/06/04)

Mechanistic investigation of the hydrogenation of ketones catalyzed by a ruthenium(II) complex featuring an N-heterocyclic carbene with a tethered primary amine donor: Evidence for an inner sphere mechanism
The complex [Ru(p-cymene)(m-CH2NH2)Cl]PF6 (1) catalyzes the H2-hydrogenation of ketones in basic THF under 25 bar of H2 at 50 °C with a turnover frequency (TOF) of up to 461 h-1 and a maximum conversion of 99%. When the substrate is acetophenone, the TOF decreases significantly as the catalyst to substrate ratio is increased. The rate law was then determined to be rate = k H[Ru]tot[H2]/(1 + Keq[ketone]), and [1] is equal to [Ru]tot if catalyst decomposition does not occur. This is consistent with the heterolytic splitting of dihydrogen at the active ruthenium species as the rate-determining step. In competition with this reaction is the reversible addition of acetophenone to the active species to give an enolate complex. The transfer to the ketone of a hydride and proton equivalent that are produced in the heterolytic splitting reaction yields the product in a fast, low activation barrier step. The kinetic isotope effect was measured using D2 gas and acetophenone-d3, and this gave values (kH/kD) of 1.33 ± 0.15 and 1.29 ± 0.15, respectively. The ruthenium hydride complex [Ru(p-cymene)(m-CH 2NH2)H]PF6 (2) was prepared, as this was postulated to be a crucial intermediate in the outer-sphere bifunctional mechanism. This is inactive under catalytic conditions unless it is activated by a base. DFT computations suggest that the energy barriers for the addition of dihydrogen, heterolytic splitting of dihydrogen, and concerted transfer of H+/H- to the ketone for the outer-sphere mechanism would be respectively 18.0, 0.2, and 33.5 kcal/mol uphill at 298 K and 1 atm. On the other hand, the energy barriers for an inner-sphere mechanism involving the decoordination of the amine group of the NHC ligand, the heterolytic splitting of dihydrogen across a Ru-O(alkoxide) bond, and hydride migration to the coordinated ketone, are respectively 15.5, 17.5, and 15.6 kcal/mol uphill at 298 K and 1 atm. This is more consistent with the experimental observation that the heterolytic splitting of dihydrogen is the turnover-limiting step. This was confirmed by showing that an analogous complex with a tethered teritiary amine group has comparable activity for the H2-hydrogenation of acetophenone. The related complex [Os(p-cymene)(m-CH2NH 2)Cl]PF6 (6) was synthesized by a transmetalation reaction with [Ni(m-CH2NH2)2](PF6) 2 (5) and [Os(p-cymene)Cl2]2, and its catalytic activity toward hydrogenation of acetophenone was also investigated.
O, Wylie W.N.,Lough, Alan J.,Morris, Robert H.
experimental part
p. 1236 - 1252
(2011/05/05)

Screening method for the evaluation of asymmetric catalysts for the reduction of aliphatic ketones
ATH reductions of aliphatic ketones in water catalyzed by ruthenium coordinated by prolinamide ligands produce alcohols with moderate enantiomeric excesses in most cases. A set of seven aliphatic ketones is proposed for a rapid evaluation of the enantioselectivity of catalysts by one-pot multi-substrates reduction. The screening of a library of prolinamides shows that according to the structure of the ketones different ligands give the best asymmetric inductions.
Boukachabia, Mourad,Zeror, Saoussen,Collin, Jacqueline,Fiaud, Jean-Claude,Zouioueche, Louisa Aribi
supporting information; experimental part
p. 1485 - 1489
(2011/05/16)

An unexpected directing effect in the asymmetric transfer hydrogenation of α,α-disubstituted ketones
α,α-Disubstituted ketones containing an aromatic ring or alkene are reduced in high enantiomeric excess using an asymmetric transfer hydrogenation catalyst. The sense of reduction indicates that the unsaturated region of the ketone adopts a position adjacent to the Ru-bound η6-arene ring in the reduction transition state.
Soni, Rina,Collinson, John-Michael,Clarkson, Guy C.,Wills, Martin
supporting information; body text
p. 4304 - 4307
(2011/10/11)

Tuning a P450 enzyme for methane oxidation
A new spin: The addition of chemically inert perfluoro carboxylic acids (green; see picture) to P450 enzymes results in dramatic activation of their catalytic activity as a result of the conversion of the Fe/heme from a low-spin to a high-spin state, and the reduction of the binding-pocket size. Together these effects allow otherwise inert substrates such as propane and even methane to be oxidized. Copyright
Zilly, Felipe E.,Acevedo, Juan P.,Augustyniak, Wojciech,Deege, Alfred,Reetz, Manfred T.
supporting information; experimental part
p. 2720 - 2724
(2011/06/10)

Formamidines - Versatile ligands for zinc-catalyzed hydrosilylation and iron-catalyzed epoxidation reactions
In the present study the abilities of catalysts modified by formamidine ligands have been examined in the zinc-catalyzed hydrosilylation of ketones and the iron-catalyzed epoxidation of stilbene, In case of hydrosilylation diethylzinc combined with easily accessible formamidine ligands allow for the efficient reduction of various aryl and alkyl ketones. By using a convenient in situ catalyst system high turnover frequencies up to more than 1.000 h -1 and a broad functional group tolerance were achieved. Moreover, the formamidine ligands were successfully applied, in the iron-catalyzed epoxidation of stilbene with hydrogen peroxide in good yield and chemoselectivity.
Enthaler, Stephan,Schroeder, Kristin,Inoue, Shigeyoshi,Eckhardt, Bjoern,Junge, Kathrin,Beller, Matthias,Driess, Matthias
experimental part
p. 4893 - 4901
(2010/10/03)

Spiroborate catalyzed reductions with N,N-diethylaniline borane
Reduction of esters, amides, and ketones by N,N-diethylaniline borane is accelerated by catalysts derived from spiroborate complexes. Esters are reduced at ambient temperature in less than 4 h with this amine borane and 5 mol % spiroborate 6. Functional group selectivity shows ketone and tertiary amide reduction is faster than ester or nitrile reduction.
Coleridge, Brian M.,Angert, Thomas P.,Marks, Lucas R.,Hamilton, Patrick N.,Sutton, Christopher P.,Matos, Karl,Burkhardt, Elizabeth R.
supporting information; experimental part
p. 5973 - 5976
(2010/11/21)

The hydrogenation of molecules with polar bonds catalyzed by a ruthenium(ii) complex bearing a chelating N-heterocyclic carbene with a primary amine donor
The complex [RuCp*(C-NH2)(py)]PF6 bearing a chelating N-heterocyclic carbene with an NH2 group (C-NH2) is an active catalyst for the H2-hydrogenation of ketones, an epoxide, ester and ketimine in basic solution. A maximum turnover frequency of 17600 h-1 is achieved under mild reaction conditions (25°C) and economical use of hydrogen (8 bar) while the TOF of a related complex with a phosphine-amine ligand is much smaller.
O, Wylie W.N,Lough, Alan J.,Morris, Robert H.
supporting information; experimental part
p. 8240 - 8242
(2011/02/22)

Synthesis and catalytic behavior of tetrakis(4-carboxyphenyl) porphyrin-periodic mesoporous organosilica
The periodic mesoporous organosilica having the tetrakis(4-carboxyphenyl) porphyrin (TCPP) unit was successfully synthesized by the direct co-condensation method using microwave with the corresponding tetra-silane. The tetra-silane precursor, TCPP-silsesquioxane was prepared through the reaction of TCPP with the APTES(3-Aminopropyltrietoxysilane). And TCPP-PMOs were synthesized with sodium metasilicate as a silica source and P123 (EO20PO70EO20) as a supramolecular template at 100 °C. The TCPP-PMO-n (n = 2.5 and 5.0, n refers to the molar percentage of TCPP precursor per silica) materials had >400 m2 g-1 of specific surface areas with ～8.7 nm of pore diameter. TCPP-PMOs were illustrated to give superiority in the organocatalytic hydrogen transfer reactions of various ketones such as acetophenone, cyclohexanone and pinacolone as well as good activity in the photocatalytic degradation of methylene blue (MB) without metal incorporation. Fe-TCPP-PMO prepared by ion-exchange method gave also good activity and selectivity in the oxidation of cyclohexene. The Royal Society of Chemistry 2010.
Jeong, Eun-Young,Burri, Abhishek,Lee, Seung-Yeop,Park, Sang-Eon
experimental part
p. 10869 - 10875
(2011/09/14)

Platinum-triethylamine-catalyzed hydrogenation of aldehydes and cyclohexanones
The first hydrogenation of aldehydes and chemoselective hydrogenation of cyclohexanones catalyzed by PtO2-Et3N are presented. An additionally attractive feature of this hydrogenation is being applicable to the complicated molecules. Three equivalent of triethylamine and 0.05 equiv of PtO2 in 95% ethanol are found to be the optimal condition.
Gao, Feng,Chen, Qiao-Hong,Wang, Feng-Peng
body text
p. 5270 - 5273
(2009/12/24)

Highly active iridium catalysts for the hydrogenation of ketones and aldehydes
The pressure hydrogenation capabilities of the iridium pincer complexes IrH2Cl[(iPr2PC2H4) 2NH] (1) and IrH3[(iPr2PC 2H4)2NH] (2) are described and compared to related results obtained previously in transfer hydrogenation. Complex 1 was shown to act as a convenient air-stable entry point to the active catalyst 2, in the presence of base and hydrogen gas. The catalysts are active in a range of solvents, including CH2Cl2 and CHCl3, in contrast to related ruthenium systems. This class of iridium complexes is very effective for the direct hydrogenation of a wide range of carbonyl compounds including ketones, diketones, α,β-unsaturated ketones and aldehydes. A catalytic cycle is proposed for this system which involves an ionic heterolytic bifunctional hydrogenation mechanism. This journal is
Chen, Xuanhua,Jia, Wenli,Guo, Rongwei,Graham, Todd W.,Gullons, Meredith A.,Abdur-Rashid, Kamaluddin
experimental part
p. 1407 - 1410
(2009/06/05)

Stoichiometric and catalytic reactivity of the N-heterocyclic carbene ruthenium hydride complexes [Ru(NHC)(L)(CO)HCl] and [Ru(NHC)(L)(CO) H(η2-BH4)] (L = NHC, PPh3)
Thermolysis of [Ru(AsPh3)3(CO)H2] with the N-aryl heterocyclic carbenes (NHCs) IMes (1,3-bis(2,4,6-trimethylphenyl) imidazol-2-ylidene), IPr (1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) or the adduct SIPr?(C6F5)H (SIPr = 1,3-bis(2,6- diisopropylphenyl)-4,5-dihydroimidazol-2-ylidene), followed by addition of CH2Cl2, affords the coordinatively unsaturated ruthenium hydride chloride complexes [Ru(NHC)2(CO)HCl] (NHC = IMes 1, IPr 2, SIPr 3). These react with CO at room temperature to yield the corresponding 18-electron dicarbonyl complexes 4-6. Reduction of 1-3 and [Ru(IMes)(PPh 3)(CO)HCl] (7) with NaBH4 yields the isolable borohydride complexes [Ru(NHC)(L)(CO)H(η2-BH4)] (8-11, L = NHC, PPh3). Both the bis-IMes complex 8 and the IMes-PPh3 species 11 react with CO at low temperature to give the η1- borohydride species [Ru(IMes)(L)(CO)2H(η1-BH 4)] (L = IMes 12, PPh3), which can be spectroscopically characterised. Upon warming to room temperature, further reaction with CO takes place to afford initially [Ru(IMes)(L)(CO)2H2] (L = IMes, L = PPh314) and, ultimately, [Ru(IMes)(L)(CO)3] (L = IMes 13, L = PPh315). Both 8 and 11 lose BH3 on addition of PMe2Ph to give [Ru(IMes)(L)(L′)(CO)H2](L = L′ = PMe2Ph; L = PPh3, L′ = PMe2Ph). Compounds 1-4 and 8-11 have been tested as catalysts for the hydrogenation of aromatic ketones in the presence of iPrOH and H2. For the reduction of acetophenone, catalytic activity varies with the NHC present, decreasing in the order IPr > IMes >> SIMes. The Royal Society of Chemistry.
Chantler, Victoria L.,Chatwin, Sarah L.,Jazzar, Rodolphe F. R.,Mahon, Mary F.,Saker, Olly,Whittlesey, Michael K.
p. 2603 - 2614
(2008/09/20)

IRIDIUM CATALYSTS FOR CATALYTIC HYDROGENATION
The present disclosure relates to a process for the reduction of compounds comprising one or more carbon-oxygen (C═O) double bonds, to provide the corresponding alcohol, comprising contacting the compound with hydrogen gas at a pressure greater than 3 atm and a catalyst comprising an iridium aminodiphosphine complex.
-
Page/Page column 6; 8

(2009/01/20)

Osmium pyme complexes for fast hydrogenation and asymmetric transfer hydrogenation of ketones
The osmium compound trans,cis-[OsCl2(PPh3) 2(Pyme)] (1) (Pyme = 1 -(pyridin-2-yl)methanamine), obtained from [OsCl2(PPh3)3] and Pyme, thermally isomerizes to cis,cis-[OsCl2(PPh3)2(Pyme)] (2) in mesitylene at 150°C. Reaction of [OsCl2(PPh3) 3] with Ph2P(CH2)4PPh2 (dppb) and Pyme in mesitylene (150°C, 4h) leads to a mixture of trans-[OsCl2(dppb)(Pyme)] (3) and cis-[OsCl2(dppb)(Pyme)] (4) in about an 1:3 molar ratio. The complex trans-[OsCl2(dppb)(Pyet) ] (5) (Pyet = 2-(pyridin-2-yl)ethanamine) is formed by reaction of [OsCl 2(PPh3)3] with dppb and Pyet in toluene at reflux. Compounds 1, 2, 5 and the mixture of isomers 3/4 efficiently catalyze the transfer hydrogenation (TH) of different ketones in refluxing 2-propanol and in the presence of NaOiPr (2.0 mol%). Interestingly, 3/4 has been proven to reduce different ketones (even bulky) by means of TH with a remarkably high turnover frequency (TOF up to 5.7 × 105h-1) and at very low loading (0.05-0.001 mol%). The system 3/4 also efficiently catalyzes the hydrogenation of many ketones (H2, 5.0 atm) in ethanol with KOtBu (2.0 mol %) at 70°C (TOF up to 1.5 × 104h-1). The in-situ-generated catalysts prepared by the reaction of [OsCl2- (PPh3)3] with Josiphos diphosphanes and (±)-1-alkyl-substituted Pyme ligands, promote the enantioselective TH of different ketones with 91-96% ee (ee = enantiomeric excess) and with a TOF of up to 1.9×104h-1 at 60°C.
Baratta, Walter,Ballico, Maurizio,Del Zotto, Alessandro,Siega, Katia,Magnolia, Santo,Rigo, Pierluigi
experimental part
p. 2557 - 2563
(2009/04/11)

Influence of residual chloride ions in alumina-supported cobalt catalysts on catalytic activity in ketone and aldehyde hydrogenation
The influence of residual chloride ions on the catalytic activity of C0/AI2O3 was investigated for liquid-phase hydrogenation of ketones and aldehydes using CI--free and Cl--containing catalysts. The Cl--free catalyst showed high activity for hydrogenation of both, whereas the Cl--contain-ing catalysts showed very low activity for ketone hydrogenation.
Otomo, Akinori,Tukagoshi, Yasuyuki,Ohshima, Masa-Aki,Kurokawa, Hideki,Miura, Hiroshi
experimental part
p. 653 - 655
(2009/04/14)

Hydrogenation of hindered ketones catalyzed by a silica-supported compact phosphine-Rh system
(Chemical Equation Presented) A heterogeneous mono(phosphine)-Rh catalyst system silica-SMAP-Rh(OMe)(cod), where silica-SMAP stands for a caged, compact trialkylphosphine (SMAP) supported on silica gel, showed broad applicability toward the hydrogenation of hindered ketones. Doubly α-branched ketones such as diisopropyl ketone was hydrogenated under nearly atmospheric conditions. Di-tert-butyl ketone could be hydrogenated under more forcing conditions.
Kawamorita, Soichiro,Hamasaka, Go,Ohmiya, Hirohisa,Hara, Kenji,Fukuoka, Atsushi,Sawamura, Masaya
supporting information; scheme or table
p. 4697 - 4700
(2009/05/26)

The active role of NHC ligands in platinum-mediated tandem hydroboration-cross coupling reactions
Stable N-heterocyclic platinum-carbene complexes are the first example of platinum-mediated regioselective H-B addition to vinylarenes and alkynes, allowing consecutive cross coupling reactions with the same catalytic system. The Royal Society of Chemistry.
Lillo, Vanesa,Mata, Jose A.,Segarra, Anna M.,Peris, Eduardo,Fernandez, Elena
p. 2184 - 2186
(2008/02/08)

From inconsistent results to high speed hydrosilylation
After noting that the presence of dihydrogen, generated in situ from the partial hydrolysis of a silane with residual water, significantly enhances the rate of the rhodium-catalysed hydrosilylation of acetophenone, we developed a high speed hydrosilylation reaction under dihydrogen pressure. The Royal Society of Chemistry.
Comte, Virginie,Balan, Cedric,Le Gendre, Pierre,Moise, Claude
p. 713 - 715
(2007/10/03)