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COLEOSIDE, A MONOTERPENE GLYCOSIDE FROM COLEUS FORSKOHLII
The alcoholic extract of the roots of Coleus forskohlii yielded caffeic acid and a new monoterpene glycoside, coleoside, characterised as cuminyl-O-β-D-glucopyranosyl(1->2)-β-D-galactopyranoside.Key Word Index - Coleus forskohlii; Labiatae; coleoside; cuminyl alcohol; caffeic acid.
Ahmed, Bahar,Vishwakarma, R. A.
p. 3309 - 3310
(1988)
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Purification and properties of reductase of the three-component p-cymene methyl hydroxylase from Pseudomonas chlororaphis subsp. aureofaciens
A novel three-component p-cymene methyl hydroxylase from Pseudomonas chlororaphis subsp. aureofaciens was reported earlier on the basis of genetic characterization and their expression catalyzing methyl group hydroxylation. This enzyme system was inductively synthesized when grown on p-cymene and had an important role in initiating p-cymene metabolism in vivo. In the present study, a NADH-dependent cytochrome c reductase protein has been purified to an electrophoretically homogeneous state and found to be involved in the hydroxylation of methyl group of p-cymene. Molecular mass of the reductase appears to be 38 kDa by SDS/PAGE and 39 kDa by gel filtration apart from one molecule of tightly bound FAD and two atoms each of iron and acid-labile sulfur per molecule of the enzyme. An apparent Km value of the enzyme for NADH is 32 ± 1.2 μM. To the best of our knowledge, this is the first report on the purification of reductase component of p-cymene methyl hydroxylase.
Dutta, Tapan K.,Dutta, Arindam,Chakraborty, Joydeep,Sarkar, Jayita,Pal Chowdhury, Piyali,Gunsalus, Irwin C.
p. 1263 - 1267
(2012)
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Palladium complexes of anionic N-heterocyclic carbenes derived from sydnones in catalysis
The anion of N-phenylsydnone, which can be generated on treatment of N-phenylsydnone with cyanomethyllithium without decomposition, can be represented as tripolar zwitterionic and as anionic N-heterocyclic carbene resonance forms. Its palladium complex was prepared from 4-bromo-3-phenylsydnone and tetrakis(triphenylphosphine)palladium and proved to be active as catalyst in Suzuki-Miyaura reactions. Thus, 2,5-dibromo-3,4-dinitrothiophene was effectively converted into 2,5-diaryl-3,4-dinitrothiophenes with 1-naphthyl, (4-trifluoromethoxy)phenyl, [4-(methylsulfanyl) phenyl], and biphenyl-4-yl boronic acid. 3-(Phenanthren-9-yl)quinoline was prepared by Suzuki-Miyaura reaction starting from 3-bromoquinoline. 1-Chloro-2,4-dinitrobenzene cross-coupled with phenyl boronic acid, 1-naphthyl boronic acid, 9-phenanthryl boronic acid. 4-Bromobenzylic alcohol gave (4-isopropylphenyl)methanol on sydnone-palladium complex-catalyzed reaction with isopropyl boronic acid.
Lücke, Ana-Luiza,Wiechmann, Sascha,Freese, Tyll,Guan, Zong,Schmidt, Andreas
p. 643 - 650
(2016)
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Preparation method of P-isopropyl benzaldehyde and from isopropylbenzene
The invention provides a method for preparing p-isopropylbenzaldehyde and from isopropylbenzaldehyde, and the preparation method comprises the following steps of: one step. The method comprises the following steps: adding cumene, an aldehyde solution, dropwise adding hydrochloric acid, heating to 80 - 88 °C after charging, and separating the phase to obtain the organic phase. The method comprises the following steps: uniformly mixing the inorganic base, the water and the phase transfer catalyst into a hydrolysis solution, adding the organic phase obtained in the step, and carrying out phase separation and purification under stirring to obtain p-isopropylbenzyl alcohol. Step III. The method comprises the following steps: adding hydrogen peroxide to isopropyl benzyl alcohol, a catalyst and a phase transfer catalyst obtained in the steps of oxidation and adding hydrogen peroxide, filtering and separating the filtrate to obtain crude aldehyde crude product and purifying to obtain p-propyl benzaldehyde. The preparation method has the advantages of being low in cost, good in process selectivity, mild in process condition and easy to realize industrialization.
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(2021/10/30)

Efficient and chemoselective hydrogenation of aldehydes catalyzed by well-defined PN3-pincer manganese(ii) catalyst precursors: An application in furfural conversion
Well-defined and air-stable PN3-pincer manganese(ii) complexes were synthesized and used for the hydrogenation of aldehydes into alcohols under mild conditions using MeOH as a solvent. This protocol is applicable for a wide range of aldehydes containing various functional groups. Importantly, α,β-unsaturated aldehydes, including ynals, are hydrogenated with the CC double bond/CC triple bond intact. Our methodology was demonstrated for the conversion of biomass derived feedstocks such as furfural and 5-formylfurfural to furfuryl alcohol and 5-(hydroxymethyl)furfuryl alcohol respectively.
Gholap, Sandeep Suryabhan,Dakhil, Abdullah Al,Chakraborty, Priyanka,Li, Huaifeng,Dutta, Indranil,Das, Pradip K.,Huang, Kuo-Wei
supporting information
p. 11815 - 11818
(2021/11/30)

Visible Light Induced Reduction and Pinacol Coupling of Aldehydes and Ketones Catalyzed by Core/Shell Quantum Dots
We present an efficient and versatile visible light-driven methodology to transform aryl aldehydes and ketones chemoselectively either to alcohols or to pinacol products with CdSe/CdS core/shell quantum dots as photocatalysts. Thiophenols were used as proton and hydrogen atom donors and as hole traps for the excited quantum dots (QDs) in these reactions. The two products can be switched from one to the other simply by changing the amount of thiophenol in the reaction system. The core/shell QD catalysts are highly efficient with a turn over number (TON) larger than 4 × 104 and 4 × 105 for the reduction to alcohol and pinacol formation, respectively, and are very stable so that they can be recycled for at least 10 times in the reactions without significant loss of catalytic activity. The additional advantages of this method include good functional group tolerance, mild reaction conditions, the allowance of selectively reducing aldehydes in the presence of ketones, and easiness for large scale reactions. Reaction mechanisms were studied by quenching experiments and a radical capture experiment, and the reasons for the switchover of the reaction pathways upon the change of reaction conditions are provided.
Xi, Zi-Wei,Yang, Lei,Wang, Dan-Yan,Feng, Chuan-Wei,Qin, Yufeng,Shen, Yong-Miao,Pu, Chaodan,Peng, Xiaogang
p. 2474 - 2488
(2021/02/05)

Silica-coated Fe3O4 magnetic nanoparticles-supported sulfonic acid as a highly active and reusable catalyst in chemoselective deprotection of tert-butyldimethylsilyl (TBDMS) ethers
Anchored propyl sulfonic acid on the surface of silica-coated magnetic nanoparticles (Fe3O4@SiO2@PrSO3H) was successfully employed in the deprotection of TBDMS ethers. The prepared magnetically separable nanocatalyst exhibited efficient catalytic activity with high conversion and selectivity in cleavage of TBDMS ethers. TBDMS ethers are efficiently cleaved to the corresponding hydroxyl compounds in methanol solution containing 2 mol% magnetic nano-catalysts. Good to excellent yields of products, simple work-up and product separation, selective cleavage of TBDMS ethers in the presence of TBDPS ethers, easy recycling of the catalyst with external magnet with no loss in its activity (7 reaction cycles) are important features of this new protocol.
Hossein Javadi, Sayed,Zareyee, Daryoush,Monfared, Azam,Didehban, Khadijeh,Mirshokraee, Sayed Ahmmad
supporting information
p. 7 - 12
(2019/11/03)

Homoleptic Zinc-Catalyzed Hydroboration of Aldehydes and Ketones in the Presence of HBpin
Here, we report the reaction between N-phenyl-o-phenylenediamine and pyrrole-2-carboxaldehyde to afford the N-phenyl-o-phenyl-enediiminopyrrole ligand {L-H2} in quantitative yield. A one-pot reaction between {L-H2} and diethylzinc (ZnEt2) in a 2:1 ratio afforded the homoleptic zinc metal complex [{L-H}2Zn] (1). The solid-state structures of ligand {L-H2} and zinc complex 1 were confirmed using X-ray crystallography. Further, complex 1 was used for chemoselective hydroboration of aldehydes and ketones in the presence of pinacolborane (HBpin) at ambient temperature to produce the corresponding boronate esters in high yield.
Kumar, Gobbilla Sai,Harinath, Adimulam,Narvariya, Rajrani,Panda, Tarun K.
supporting information
p. 467 - 474
(2020/02/04)

Novel palladium nanoparticles supported on mesoporous natural phosphate: Catalytic ability for the preparation of aromatic hydrocarbons from natural terpenes
Various ratios of palladium nanoparticles supported on mesoporous natural phosphate (Pd@NP) were prepared using the wetness impregnation method. The prepared catalysts were characterized by IR, XRD, CV, SEM, EDX, XRF, TEM and BET analysis. The reduction and preparation of the palladium nanoparticles afford a crystallite size of 10.88 nm. The performance of the synthesized catalyst was investigated in the solvent-free dehydroaromatization of α-, β- and γ-himachalene mixture from Cedrus atlantica oil as a model substrate. In order to achieve an efficient and selective catalysis, the catalytic dehydroaromatization of various terpenes such as limonene, limonaketone, carvone, carveol and perillyl alcohol was studied. The Pd@NP catalyst performed a high catalytic activity, selectivity and recyclability in the terpenes dehydroaromatization reaction.
Mekkaoui, Ayoub Abdelkader,Aberkouks, Abderrazak,Fkhar, Lahcen,Ait Ali, Mustapha,El Firdoussi, Larbi,El Houssame, Soufiane
(2020/07/24)

Triazole derivative as well as preparation method and application thereof
The invention relates to a triazole derivative as well as a preparation method and application thereof, which belong to the technical field of organic synthetic drugs. The structure of the triazole derivative is shown as a formula I. In the formula I, R1 and R2 are H, Cl, Br,-CF3,-CH(CH3)2 or -OCH3, and R1 and R2 are not H at the same time. R3 is -CH2 or -COCH2; X and Y are N or C, X and Y are not C at the same time, and X and Y are not N at the same time. The triazole derivative disclosed by the invention has a certain inhibition effect on germs of various crop diseases. Small toxic andside effects on plants are achieved. The preparation method of the triazole derivative is simple.
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Paragraph 0053-0055; 0065-0067

(2020/06/09)

Diethylsilane as a Powerful Reagent in Au Nanoparticle-Catalyzed Reductive Transformations
Diethylsilane (Et2SiH2), a simple and readily available dihydrosilane, that exhibits superior reactivity, as compared to monohydrosilanes, in a series of reductive transformations catalyzed by recyclable and reusable Au nanoparticles (1 mol-%) supported on TiO2. It reduces aldehydes or ketones almost instantaneously at ambient conditions. It can be used in a one pot rapid reductive amination procedure, in which premixing of aldehyde and amine is required prior to the addition of the reducing agent and the catalyst, even in a protic solvent. An unprecedented method for the synthesis of N-arylisoindolines is also shown in the reductive amination between o-phthalaldehyde and anilines. In this transformation, it is proposed that the intermediate N,2-diphenylisoindolin-1-imines are reduced stepwise to the isoindolines. Finally, Et2SiH2 readily reduces amides into amines in excellent yields and shorter reaction times relative to previously known analogous nano Au(0)-catalyzed protocols.
Louka, Anastasia,Kidonakis, Marios,Saridakis, Iakovos,Zantioti-Chatzouda, Elisavet-Maria,Stratakis, Manolis
p. 3508 - 3514
(2020/06/02)

Manganese catalyzed transfer hydrogenation of biomass-derived aldehydes: Insights to the catalytic performance and mechanism
Manganese catalyzed transfer hydrogenation (CTH) of aldehydes is an attractive method for the synthesis of alcohols. Here, we report a novel and efficient MnO?C-N catalyst for the CTH of biomass-derived 5-hydroxymethylfurfural and other aldehydes to alcohols in high yields. Catalytic experimental studies showed that the MnO and nitrogen-doping are responsible for the high selectivity and high conversion, respectively. Isotopic labelling experiments demonstrated that the CTH of aldehydes to alcohols over MnO?C-N is via a route by direct hydrogen transfer. Kinetic studies revealed that the N-doping can improve the reaction rate and reduce the activation energy of the aldehydes conversion. DFT calculations also indicated that both pyridine N and pyrrolic N doping can reduce the energy barrier for acetone desorption by the interaction between N and hydroxyl-H of alcohol. Furthermore, MnO?C-N showed good recyclability for at least five reaction cycles. We anticipate that these results can drive progress in the manganese catalyzed transfer hydrogenation reaction.
Chen, Binglin,Feng, Yunchao,Lin, Lu,Long, Sishi,Sperry, Jonathan,Sun, Yong,Tang, Xing,Xu, Wanjie,Yan, Guihua,Zeng, Xianhai
p. 157 - 165
(2020/06/27)

Nanoporous Na+-montmorillonite perchloric acid as an efficient and recyclable catalyst for the chemoselective protection of hydroxyl groups
Nanoporous Na+-montmorillonite perchloric acid as a novel heterogeneous reusable solid acid catalyst was easily prepared by treatment of Na+-montmorillonite as a cheap and commercially available support with perchloric acid. The catalyst was characterized using a variety of techniques including X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), energy dispersive X-ray spectroscopy (EDX), pH analysis and determination of the Hammett acidity function. The prepared reagent showed excellent catalytic activity for the chemoselective conversion of alcohols and phenols to their corresponding trimethylsilyl ethers with 1,1,1,3,3,3-hexamethyldisilazane (HMDS) at room temperature. Deprotection of the resulting trimethylsilyl ethers can also be carried out using the same catalyst in ethanol. All reactions were performed under mild and completely heterogeneous reaction conditions in good to excellent yields. The notable advantages of this protocol are: short reaction times, high yields, availability and low cost of the reagent, easy work-up procedure and the reusability of the catalyst during a simple filtration.
Mashhadinezhad, Maryam,Shirini, Farhad,Mamaghani, Manouchehr
p. 2099 - 2107
(2019/01/03)

A method of synthesis of primary alcohol (by machine translation)
The invention discloses a method for synthesizing a primary alcohol, using transition metal catalysis, the use of isopropanol as a hydrogen source to synthesize primary alcohol, the reaction not only using a cheap, environmental protection of isopropanol as a hydrogen source and solvent, and has high yield, environmental protection and the like, so that the reaction has broad prospects for development. (by machine translation)
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Paragraph 0045; 0046; 0047; 0048; 0049

(2019/03/17)

Ambient-pressure hydrogenation of ketones and aldehydes by a metal-ligand bifunctional catalyst [Cp*Ir(2,2′-bpyO)(H2O)] without using base
An efficient catalytic system for hydrogenation of ketones and aldehydes using a Cp*Ir complex [Cp*Ir(2,2′-bpyO)(H2O)] bearing a bipyridine-based functional ligand as catalyst has been developed. A wide variety of secondary and primary alcohols were synthesized by the catalyzed hydrogenation of ketones and aldehydes under facile atmospheric-pressure without a base. The catalyst also displays an excellent chemoselectivity towards other carbonyl functionalities and unsaturated motifs. This catalytic system exhibits high activity for hydrogenation of ketones and aldehydes with H2 gas.
Wang, Rongzhou,Qi, Jipeng,Yue, Yuancheng,Lian, Zhe,Xiao, Haibin,Zhuo, Shuping,Xing, Lingbao
(2019/07/30)

Mild palladium-catalysed highly efficient hydrogenation of CN, C-NO2, and CO bonds using H2 of 1 atm in H2O
Here we present the first example of a mild and high-efficiency protocol enabling a process in water using 1 atm of H2 for the efficient and selective hydrogenation of nitriles, nitro compounds, ketones, and aldehydes to yield primary amines and alcohols with satisfactory yields of up to >99%. Several palladium-based nanoparticle catalysts were prepared from K2PdCl4 and ligands, and one of them was found to be the best and most suitable for the hydrogenation of CN, C-NO2, and CO bonds. In addition, the catalyst Pd-NPs can be easily recycled and reused without losing their activity and selectivity. A plausible mechanism for the hydrogenation of a CN bond was also proposed, representing the first example that possesses great potential for sustainable industrial purposes.
Liu, Yaxu,He, Shaopo,Quan, Ziyi,Cai, Huizhuo,Zhao, Yang,Wang, Bo
supporting information
p. 830 - 838
(2019/02/27)

Atomic-layer-deposition-formed sacrificial template for the construction of an MIL-53 shell to increase selectivity of hydrogenation reactions
We developed a method for using atomic layer deposition (ALD)-formed layers of Al2O3 as a sacrificial template to generate MIL-53(Al). The MOF shell in the CeO2/Pd@MIL-53(Al) configuration not only stabilized the Pd nanoparticles, but also regulated the selectivity of the hydrogenation of unsaturated aldehydes. This work represents the first demonstration of ALD-formed layers of metal oxides serving as sacrificial templates in the design of MOF-shell-based sandwich-type structures.
Xu, Tiantian,Sun, Kai,Gao, Daowei,Li, Cuncheng,Hu, Xun,Chen, Guozhu
supporting information
p. 7651 - 7654
(2019/07/04)

Cu1-Cu0 bicomponent CuNPs@ZIF-8 for highly selective hydrogenation of biomass derived 5-hydroxymethylfurfural
99% yield of 2,5-dihydroxymethylfuran (DHMF) was achieved from biomass derived 5-hydroxymethylfurfural (HMF) with novel CuNPs@ZIF-8 using a relatively low hydrogen pressure and short reaction time. The activation energy of transformation of HMF to DHMF is only 39 kJ mol-1 and the TOF value reached is 21 h-1. The coexistence of Cu1 and Cu0 in Cu species is demonstrated to contribute to the high activity for the hydrogenation of HMF to DHMF.
Feng, Yunchao,Yan, Guihua,Wang, Ting,Jia, Wenlong,Zeng, Xianhai,Sperry, Jonathan,Sun, Yong,Tang, Xing,Lei, Tingzhou,Lin, Lu
supporting information
p. 4319 - 4323
(2019/08/22)

Transfer Hydrogenation of Aldehydes and Ketones with Isopropanol under Neutral Conditions Catalyzed by a Metal-Ligand Bifunctional Catalyst [Cp?Ir(2,2′-bpyO)(H2O)]
A Cp?Ir complex bearing a functional bipyridonate ligand [Cp?Ir(2,2′-bpyO)(H2O)] was found to be a highly efficient and general catalyst for transfer hydrogenation of aldehydes and chemoselective transfer hydrogenation of unsaturated aldehydes with isopropanol under neutral conditions. It was noteworthy that many readily reducible or labile functional groups such as nitro, cyano, ester, and halide did not undergo any change under the reaction conditions. Furthermore, this catalytic system exhibited high activity for transfer hydrogenation of ketones with isopropanol. Notably, this research exhibited new potential of metal-ligand bifunctional catalysts for transfer hydrogenation.
Wang, Rongzhou,Tang, Yawen,Xu, Meng,Meng, Chong,Li, Feng
p. 2274 - 2281
(2018/02/23)

An alternative route to tethered Ru(II) transfer hydrogenation catalysts
A new route towards a series of tethered η6-arene/Ru(II) catalysts for use in the transfer and pressure hydrogenation of ketones and aldehydes to alcohols is reported. The route proceeds through the formation of an amide from the diamine precursor, followed by reduction, rather than the direct alkylation of the diamine. This has the advantage that dialkylation of the amine is avoided during the synthesis. Through this new route, both racemic and enantiomerically-pure η6-arene/Ru(II) tethered catalysts can be prepared in high yield.
Hodgkinson, Roy,Jur?ík, Václav,Nedden, Hans,Blackaby, Andrew,Wills, Martin
supporting information
p. 930 - 933
(2018/02/12)

The Oxidation of Hydrophobic Aromatic Substrates by Using a Variant of the P450 Monooxygenase CYP101B1
The cytochrome P450 monooxygenase CYP101B1, from a Novosphingobium bacterium is able to bind and oxidise aromatic substrates but at a lower activity and efficiency than norisoprenoids and monoterpenoid esters. Histidine 85 of CYP101B1 aligns with tyrosine 96 of CYP101A1, which, in the latter enzyme forms the only hydrophilic interaction with its substrate, camphor. The histidine residue of CYP101B1 was mutated to phenylalanine with the aim of improving the activity of the enzyme for hydrophobic substrates. The H85F mutant lowered the binding affinity and activity of the enzyme for β-ionone and altered the oxidation selectivity. This variant also showed enhanced affinity and activity towards alkylbenzenes, styrenes and methylnaphthalenes. For example the rate of product formation for acenaphthene oxidation was improved sixfold to 245 nmol per nmol CYP per min. Certain disubstituted naphthalenes and substrates, such as phenylcyclohexane and biphenyls, were oxidised with lower activity by the H85F variant. Variants at H85 (A and G) designed to introduce additional space into the active site so as to accommodate these larger substrates did not improve the oxidation activity. As the H85F mutant of CYP101B1 improved the oxidation of hydrophobic substrates, this residue is likely to be in the substrate binding pocket or the access channel of the enzyme. The side chain of the histidine might interact with the carbonyl groups of the favoured norisoprenoid substrates of CYP101B1.
Sarkar, Md. Raihan,Lee, Joel H. Z.,Bell, Stephen G.
p. 2119 - 2128
(2017/10/12)

Transfer hydrogenation of aromatic and linear aldehydes catalyzed using Cp*Ir(pyridinesulfonamide)Cl complexes under base-free conditions
Cp*Ir(pyridinesulfonamide)Cl (Cp*?=?pentamethylcyclopentadienyl) precatalysts 1–7 are active for the transfer hydrogenation of aryl, alkyl, and heterocyclic aldehydes. Catalysis is conducted under base-free conditions in air without dried or degassed substrates and solvents. These reductions occur rapidly in moderate to high conversion (39–100%). Benzaldehyde derivatives are reduced to alcohols within 30?min?at 85?°C using 1?mol% iridium precatalyst; reduction also occurs at lower temperatures and loadings (60?°C, 0.50?mol% precatalyst). Benzaldehyde derivatives that possess electron-rich and electron-poor substituents in the para position, including base-sensitive 4-hydroxybenzaldehyde, are readily reduced. Aryl aldehydes containing electron-poor groups are reduced faster than substrates possessing electron-rich moieties. Reduction of the positional isomers of methoxybenzaldehyde and isopropylbenzaldehyde shows highest reduction for the ortho isomer, followed by the meta isomer. Heterocyclic substrates, including biomass derived 5-hydroxymethylfurfural and 2-furfural, were reduced selectively to the alcohol. Decyl aldehyde was reduced to the linear alcohol; importantly self-condensation was not observed. Competition studies demonstrated selective reduction of aldehydes over ketones and a mercury poisoning experiment supports a homogeneous catalyzed pathway.
Townsend, Tanya M.,Kirby, Christopher,Ruff, Andrew,O'Connor, Abby R.
p. 7 - 13
(2017/05/19)

Introduction of PEG-SANM nanocomposite as a new and highly efficient reagent for the promotion of the silylation of alcohols and phenols and deprotection of the silyl ethers
Poly (ethylene glycol)-sulfonated sodium montmorillonite (PEG-SANM) nanocomposite was prepared by a simple method and characterized using XRD, TGA, SEM, TEM, and FT-IR techniques. After preparation and characterization, this reagent was used as a highly efficient and reusable solid acid catalyst for the chemoselective silylation of alcohols and phenols and deprotection of the obtained silyl ethers. Themethod offers several advantages including high to excellent yields of the products, short reaction times, easy preparation of the catalyst and easy work-up procedure. In addition, the catalyst can be recycled and reused at least for five times without significant decrease in the catalytic activity.
Shirini, Farhad,Shojaei, Abdollah Fallah,Heirati, Seyedeh Zahra Dalil
p. 944 - 951
(2016/07/06)

The catalytic dehydrogenation of perilla alcohol as the raw material in the synthetic cuminyl alcohol
The invention relates to a new method for preparing cuminol. In the method, cuminol is prepared by catalytic dehydrogenation with perilla alcohol directly synthesized from natural product turpentine as a raw material; the reaction is carried out in liquid phase under normal pressure; and cuminol yield is up to 95%. The method has industrialized application potential, can promote the development of forestry and chemical industry in China, realizes the utilization of renewable resources and circulating economy, and reduces the raw material cost; and the product is safe and reliable, can be widely applied to the fields of food, medicines, spices and the like, and has excellent social and economic benefits.
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Paragraph 0011; 0012

(2016/10/07)

O-alkylhydroxylamines as rationally-designed mechanism-based inhibitors of indoleamine 2,3-dioxygenase-1
Indoleamine 2,3-dioxygenase-1 (IDO1) is a promising therapeutic target for the treatment of cancer, chronic viral infections, and other diseases characterized by pathological immune suppression. Recently important advances have been made in understanding IDO1's catalytic mechanism. Although much remains to be discovered, there is strong evidence that the mechanism proceeds through a heme-iron bound alkylperoxy transition or intermediate state. Accordingly, we explored stable structural mimics of the alkylperoxy species and provide evidence that such structures do mimic the alkylperoxy transition or intermediate state. We discovered that O-benzylhydroxylamine, a commercially available compound, is a potent sub-micromolar inhibitor of IDO1. Structure-activity studies of over forty derivatives of O-benzylhydroxylamine led to further improvement in inhibitor potency, particularly with the addition of halogen atoms to the meta position of the aromatic ring. The most potent derivatives and the lead, O-benzylhydroxylamine, have high ligand efficiency values, which are considered an important criterion for successful drug development. Notably, two of the most potent compounds demonstrated nanomolar-level cell-based potency and limited toxicity. The combination of the simplicity of the structures of these compounds and their excellent cellular activity makes them quite attractive for biological exploration of IDO1 function and antitumor therapeutic applications.
Malachowski, William P.,Winters, Maria,DuHadaway, James B.,Lewis-Ballester, Ariel,Badir, Shorouk,Wai, Jenny,Rahman, Maisha,Sheikh, Eesha,LaLonde, Judith M.,Yeh, Syun-Ru,Prendergast, George C.,Muller, Alexander J.
supporting information
p. 564 - 576
(2016/01/09)

An Efficient, Stable and Reusable Palladium Nanocatalyst: Chemoselective Reduction of Aldehydes with Molecular Hydrogen in Water
Palladium nanoparticles (Pd-BNP) stabilized by a binaphthyl-backbone can be efficiently used for the chemoselective reduction of aldehydes in the presence of hydrogen at room temperature in water. The Pd-BNP catalyst is easily recovered and reused for five catalytic cycles. (Figure presented.).
Kotha, Surya Srinivas,Sharma, Nidhi,Sekar, Govindasamy
supporting information
p. 1694 - 1698
(2016/10/13)

Mn(II) and VO(IV) Schiff base complexes encapsulated in nanocavities of zeolite-Y: catalytic activity toward oxidation of alkenes and reduction of aldehydes
Oxovanadium(IV) and manganese(II) complexes of two Schiff base ligands, bis(2,4-dihydroxyacetophenone)-1,2-propandiimine (H2L1) and bis(2,4-dihydroxyacetophenone)-ethylenediimine (H2L2) were synthesized and characterized. The encapsulation of these complexes in the nanocavities of zeolite-Y was achieved by a flexible ligand method. The prepared heterogeneous catalysts have been characterized by FTIR, NMR and atomic absorption spectroscopy, X-ray diffraction patterns, scanning electron microscopy and BET. The catalytic activities of the encapsulated complexes were studied in the oxidation of alkenes with H2O2 and the reduction of aldehydes with NaBH4. In most cases, the manganese (II) complexes (MnL1-Y, MnL2-Y) showed better activity than the oxovanadium (IV) complexes (VOL1-Y, VOL2-Y) in both oxidation of alkenes and reduction of aldehydes. The catalytic activity of the recovered catalysts was compared with the fresh ones.
Rayati, Saeed,Shokoohi, Saeedeh,Bohloulbandi, Elaheh
p. 1983 - 1991
(2016/09/16)

The efficient and selective biocatalytic oxidation of norisoprenoid and aromatic substrates by CYP101B1 from Novosphingobium aromaticivorans DSM12444
CYP101B1 from Novosphingobium aromaticivorans DSM12444 is a homologue of CYP101A1 (P450cam) from Pseudomonas putida and the CYP101D1, CYP101D2 and CYP101C1 enzymes from the same bacterium. CYP101B1 binds norisoprenoids more tightly than camphor and efficiently hydroxylates substrates in combination with ferredoxin reductase, ArR, and [2Fe-2S] ferredoxin, Arx, electron transfer partners. The norisoprenoids, α-ionone and β-damascone are both oxidised by CYP101B1 with high product formation activity, >500 min-1. α-Ionone oxidation occurred regioselectively at the allylic C3 position while β-damascone was hydroxylated predominantly at C3, 86%, with the main competing minor product arising from oxidation at the allylic C4 position (11%). When incorporated into a whole-cell oxidation system, with ArR and Arx, CYP101B1 is also capable of oxidising the aromatic compound indole. Other aromatic molecules including phenylcyclohexane and p-cymene were tested and both were hydroxylated by CYP101B1. Phenylcyclohexane was selectively oxidised to trans-4-phenylcyclohexanol while p-cymene was hydroxylated at the benzylic carbons to yield a mixture of isopropylbenzyl alcohol and p-α,α-trimethylbenzylalcohol. Trans-4-Phenylcyclohexanol was formed with a product formation rate of 141 min-1 and was five times more active than the oxidation of p-cymene. This journal is
Hall, Emma A.,Bell, Stephen G.
p. 5762 - 5773
(2015/03/05)

Highly efficient, general hydrogenation of aldehydes catalyzed by PNP iron pincer complexes
A general protocol for the synthetically and industrially important hydrogenation of aldehydes to alcohols is reported. The reactions are catalyzed by well-defined iron pincer complexes that are capable of hydrogenation of aliphatic and aromatic aldehydes selectively and efficiently under mild conditions, with unprecedented turnover numbers.
Zell, Thomas,Ben-David, Yehoshoa,Milstein, David
p. 822 - 826
(2015/02/19)

Signal transduction and amplification through enzyme-triggered ligand release and accelerated catalysis
Signal transduction and signal amplification are both important mechanisms used within biological signalling pathways. Inspired by this process, we have developed a signal amplification methodology that utilises the selectivity and high activity of enzymes in combination with the robustness and generality of an organometallic catalyst, achieving a hybrid biological and synthetic catalyst cascade. A proligand enzyme substrate was designed to selectively self-immolate in the presence of the enzyme to release a ligand that can bind to a metal pre-catalyst and accelerate the rate of a transfer hydrogenation reaction. Enzyme-triggered catalytic signal amplification was then applied to a range of catalyst substrates demonstrating that signal amplification and signal transduction can both be achieved through this methodology.
Goggins, Sean,Marsh, Barrie J.,Lubben, Anneke T.,Frost, Christopher G.
p. 4978 - 4985
(2015/07/27)

N,N,N′,N′-Tetramethylenediamine dioxide (TMEDAO2) facilitates atom economical/open atmosphere Ley-Griffith (TPAP) tandem oxidation-Wittig reactions
N,N,N′,N′-Tetramethylethylenediamine dioxide (TMEDAO2) was explored as a more atom economical co-oxidant for the Ley-Griffith oxidation of alcohols to aldehydes. TMEDAO2 was found to selectivity oxidise benzylic and allylic alcohols in comparable yields to that of the standard Ley-Griffith co-oxidant (NMO). Importantly TMEDAO2 facilitated tandem Ley-Griffith-Wittig reactions with stabilised ylides, in good to excellent yields, without the requirement of anhydrous conditions.
Read, Christopher D. G.,Moore, Peter W.,Williams, Craig M.
supporting information
p. 4537 - 4540
(2015/09/15)

Metal-free, visible-light photoredox catalysis: Transformation of arylmethyl bromides to alcohols and aldehydes
A mild, simple, and controllable metal-free photocatalytic system for the transformation of arylmethyl bromides to corresponding alcohols and aldehydes in high yields with visible-light irradiation has been achieved. Eosin Y was found to be an efficient promoter for this oxidative dehalogenation reaction under photo irradiation conditions.
Li, Jian,Wang, Hongni,Liu, Li,Sun, Jiangtao
p. 49974 - 49978
(2014/12/10)

Efficient hydrosilylation of carbonyl compounds by 1,1,3,3-tetramethyldisiloxane catalyzed by Au/TiO2
1,1,3,3-Tetramethyldisiloxane (TMDS) is a highly reactive reducing reagent in the Au/TiO2-catalyzed hydrosilylation of carbonyl compounds relative to monohydrosilanes. The reduction of aldehydes or ketones with TMDS can be performed on many occasions at ambient conditions within short reaction times and at low loading levels of gold, whereas typical monohydrosilanes require excess heating and prolonged time for completion. The product yields are excellent, while almost stoichiometric amounts of carbonyl compounds and TMDS can be used. It is postulated that the enhanced reactivity of TMDS is attributed to the formation of a gold dihydride intermediate. This intermediate is also supported by the fact that double hydrosilylation of carbonyl compounds by TMDS is a negligible pathway.
Vasilikogiannaki, Eleni,Titilas, Ioannis,Gryparis, Charis,Louka, Anastasia,Lykakis, Ioannis N.,Stratakis, Manolis
p. 6106 - 6113
(2014/12/10)

Palladium-catalysed direct cross-coupling of secondary alkyllithium reagents
Palladium-catalysed cross-coupling of secondary C(sp3) organometallic reagents has been a long-standing challenge in organic synthesis, due to the problems associated with undesired isomerisation or the formation of reduction products. Based on our recently developed catalytic C-C bond formation with organolithium reagents, herein we present a Pd-catalysed cross-coupling of secondary alkyllithium reagents with aryl and alkenyl bromides. The reaction proceeds at room temperature and on short timescales with high selectivity and yields. This methodology is also applicable to hindered aryl bromides, which are a major challenge in the field of metal catalysed cross-coupling reactions.
Vila, Carlos,Giannerini, Massimo,Hornillos, Valentin,Fananas-Mastral, Martin,Feringa, Ben L.
p. 1361 - 1367
(2014/03/21)

Highly efficient transfer hydrogenation of aldehydes and ketones using potassium formate over AlO(OH)-entrapped ruthenium catalysts
Ruthenium encapsulated in an aluminium oxyhydroxide-support was investigated for the transfer hydrogenation of aldehydes and ketones with potassium formate as a sustainable green hydrogen donor. The entrapped ruthenium were narrowly distributed with mean diameters of 1.5-1.8 nm. XPS studies show that the ruthenium was present as Ru0 and Ru3+. The catalysts showed high activity even at low metal loadings of 0.5-2 wt.%. The maximum TOF for benzaldehyde hydrogenation was over 1 wt.% Ru. The reduction of aromatic and aliphatic aldehydes was facile and occurred with 100% yield. In comparison, ketones were less readily reduced although moderate to excellent yields could be obtained after a longer reaction time. No leaching of ruthenium was observed in contrast to a catalyst prepared by wet impregnation. Washing of the used catalyst with water and ethanol effectively removed the deposited bicarbonate co-product and the recycled catalyst maintained its activity up to five runs.
Gao, Yanxiu,Jaenicke, Stephan,Chuah, Gaik-Khuan
p. 51 - 58
(2014/08/18)

Efficient hydrogenation of ketones and aldehydes catalyzed by well-defined iron(II) PNP pincer complexes: Evidence for an insertion mechanism
We have prepared and structurally characterized a new class of Fe(II) PNP pincer hydride complexes [Fe(PNP-iPr)(H)(CO)(L)]n (L = Br-, CH3CN, pyridine, PMe3, SCN-, CO, BH4-; n = 0, +1) based on the 2,6-diaminopyridine scaffold where the PiPr2 moieties of the PNP ligand are connected to the pyridine ring via NH and/or NMe spacers. Complexes [Fe(PNP-iPr)(H)(CO)(L)]n with labile ligands (L = Br-, CH3CN, BH4-) and NH spacers are efficient catalysts for the hydrogenation of both ketones and aldehydes to alcohols under mild conditions, while those containing inert ligands (L = pyridine, PMe3, SCN-, CO) are catalytically inactive. Interestingly, complex [Fe(PNPMe-iPr)(H)(CO)(Br)], featuring NMe spacers, is an efficient catalyst for the chemoselective hydrogenation of aldehydes. The first type of complexes involves deprotonation of the PNP ligand as well as heterolytic dihydrogen cleavage via metal-alkoxide cooperation, but no reversible aromatization/deprotonation of the PNP ligand. In the case of the N-methylated complex the mechanism remains unclear, but obviously does not allow bifunctional activation of dihydrogen. The experimental results complemented by DFT calculations strongly support an insertion of the C=O bond of the carbonyl compound into the Fe-H bond.
Gorgas, Nikolaus,St?ger, Berthold,Veiros, Luis F.,Pittenauer, Ernst,Allmaier, Günter,Kirchner, Karl
p. 6905 - 6914
(2015/02/19)

Nanosized ruthenium particles decorated carbon nanofibers as active catalysts for the oxidation of p-cymene by molecular oxygen
Highly dispersed, nanosized ruthenium (Ru) particles anchored on carbon nanofibers (CNFs) with varying Ru loadings (1-7 wt.%) showed effective catalytic activity in the aerobic oxidation of p-cymene using molecular oxygen. The activity of the Ru catalysts was influenced by the structural properties that resulted from the different metal loadings and by various reaction variables, such as the temperature, the amount of catalyst and the type of radical-initiator substrate. Under optimized reaction conditions, the 3%Ru/CNF catalyst exhibited excellent performance with a selectivity of 42% toward primary cymene hydroperoxide (PCHP) and 33% toward tertiary cymene hydroperoxide (TCHP) at 55% p-cymene conversion achieved within 5 h at 90 °C. The results demonstrated that the direct participation of the catalyst in p-cymene CH bond activation occurred via catalytic decomposition of tertiary-butyl hydroperoxide (TBHP), which was added as an initiator, into a free-radical chain initiator rather than the direct H-atom abstraction by the catalyst itself. The catalytic efficacy displayed by the Ru/CNF catalysts provides encouraging results for the activation of CH bonds of liquid-phase alkyl aromatic hydrocarbons, such as p-cymene, toward the introduction of an oxygen atom. The catalyst was reusable for five consecutive reaction cycles without appreciable loss of activity. Moreover, Ru/CNF catalyst was active for extended substrate scope application in the oxidation of other alkyl-substituted aromatics.
Makgwane, Peter R.,Ray, Suprakas Sinha
p. 1 - 11
(2013/06/26)

A molecularly defined iron-catalyst for the selective hydrogenation of α,β-unsaturated aldehydes
A selective iron-based catalyst system for the hydrogenation of α,β-unsaturated aldehydes to allylic alcohols is presented. Applying the defined iron-tetraphos complex [FeF(L)][BF4] (L=P(PhPPh 2)3) in the presence of trifluoroacetic acid a broad range of aldehydes are reduced in high yields using low catalyst loadings (0.05-1 mol %). Excellent chemoselectivity for the reduction of aldehydes in the presence of other reducible moieties, for example, ketones, olefins, esters, etc. is achieved. Based on the in situ detected hydride species [FeH(H 2)(L)]+ a catalytic cycle is proposed that is supported by computational calculations. Copyright
Wienh?fer, Gerrit,Westerhaus, Felix A.,Junge, Kathrin,Ludwig, Ralf,Beller, Matthias
supporting information
p. 7701 - 7707
(2013/07/11)

Identification of a marine NADPH-dependent aldehyde reductase for chemoselective reduction of aldehydes
A putative aldehyde reductase gene from Oceanospirillum sp. MED92 was overexpressed in Escherichia coli. The recombinant protein (OsAR) was characterized as a monomeric NADPH-dependent aldehyde reductase. The kinetic parameters Km and kcat of OsAR were 0.89 ± 0.08 mM and 11.07 ± 0.99 s-1 for benzaldehyde, 0.04 ± 0.01 mM and 6.05 ± 1.56 s-1 for NADPH, respectively. This enzyme exhibited high activity toward a variety of aromatic and aliphatic aldehydes, but no activity toward ketones. As such, it catalyzed the chemoselective reduction of aldehydes in the presence of ketones, as demonstrated by the reduction of 4-acetylbenzaldehyde or the mixture of hexanal and 2-nonanone, showing the application potential of this marine enzyme in such selective reduction of synthetic importance.
Li, Guangyue,Ren, Jie,Wu, Qiaqing,Feng, Jinhui,Zhu, Dunming,Ma, Yanhe
p. 17 - 22
(2013/05/08)

Fast and selective iron-catalyzed transfer hydrogenations of aldehydes
An efficient iron-based catalyst system consisting of Fe(BF)4$6H2O and P(CH2CH2PPh2)3 [tetraphos, (PP3)] is presented for the highly selective transfer hydrogenation of aromatic, aliphatic, and a,b-unsaturated aldehydes. A wide range of substrates including aldehydes with other reducible functional groups gave the corresponding alcohols in good yields. Formic acid is applied as a cheap, environmentally benign and easy to handle hydrogen source. Notable features of the presented methodology are the fast reactions under mild conditions. Advantageously compared to most transfer hydrogenations, no stoichiometric amounts of base additives are required.
Wienh?fer, Gerrit,Westerhaus, Felix A.,Junge, Kathrin,Beller, Matthias
p. 156 - 159
(2013/10/01)

ROR MODULATORS AND THEIR USES
The invention relates to ROR modulators; compositions comprising an effective amount of a ROR modulator; and methods for treating or preventing diseases associated with ROR. The invention is based in part on the discovery of ROR modulators which interact with RORa and/or RORy and thereby inhibit or induce RORa and/or RORy-activity, and RORa- and/or RORy-regulated target gene and protein expression.
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Paragraph 0099

(2013/11/05)

Preparation, characterization and use of 1,3-disulfonic acid imidazolium hydrogen sulfate as an efficient, halogen-free and reusable ionic liquid catalyst for the trimethylsilyl protection of hydroxyl groups and deprotection of the obtained trimethylsilanes
Novel 1,3-disulfonic acid imidazolium hydrogen sulfate, a halogen-free ionic liquid, is a recyclable and eco-benign catalyst for the trimethylsilyl protection of hydroxyl groups at room temperature under solvent free conditions to afford trimethylsilanes in excellent yields (92-100%) and in very short reaction times (1-5 min). Deprotection of the resulting trimethylsilanes can also be achieved using the same catalyst in methanol. The catalyst was characterized by IR, 1H NMR, 13C NMR and MS studies. All the products were extensively characterized by IR, 1H NMR, MS, and elemental and melting point analyses. This new method consistently has the advantages of excellent yields and short reaction times. Further, the catalyst can be recovered and reused for several times without loss of activity. The work-up of the reaction consists of a simple separation, followed by concentration of the crude product and purification.
Shirini, Farhad,Khaligh, Nader Ghaffari,Akbari-Dadamahaleh, Somayeh
p. 15 - 23
(2013/01/14)

β-cyclodextrin as inverse phase transfer catalyst on the electrocatalytic hydrogenation of organic compounds in water
The optimum conditions for the electrocatalytic hydrogenation (ECH) of benzaldehyde in water, using a nickel sacrificial anode (SA) (referred to as ECH-SA) and β-cyclodextrin (β-CyD) as inverse phase transfer catalyst (IPTC) were determined. Four parameters were investigated: the morphology of the nickel deposited on the cathode matrix (Cu, Fe, Ni or Fe/Ni alloy (64:36)) during a pre-electrolysis, the size of the CyD cavity, the concentration of β-CyD, the supporting electrolyte concentration and the current density applied. The results showed that a Ni matrix together with ultrasound pre-electrolysis treatment allowed a nanostructured nickel deposit on the cathode surface. Under the best electrolysis conditions (2.8 mmol dm -3 of β-CyD, 1.0 mol dm-3 of NH4Cl and a current density of 330 mA dm-2), the yield of benzyl alcohol (99%) was 27% higher than that obtained under the same conditions but in the absence of β-CyD. Taking into account the hydrophobic character of the β-CyD, the best conditions of the ECH-SA method were applied to the hydrogenation of a variety of organic substrates. Excellent yields and current efficiencies were obtained with arylbenzaldehydes and acetophenone. ECH-SA of styrene gave moderate yield and current efficiency, and the hydrogenation of a terminal non-conjugated olefin (safrole) was not efficient.
Vilar, Márcio,Navarro, Marcelo
experimental part
p. 270 - 278
(2012/03/13)

PROCESS FOR PREPARING 4-ISOPROPYLCYCLOHEXYLMETHANOL
The present invention relates to a process for preparing 4-isopropylcyclohexylmethanol (IPCHM) from para-cymene. The process for preparing 4-isopropylcyclohexylmethanol (IPCHM) comprises an electrochemical process for preparing a mixture of 4-isopropylbenzaldehyde dimethyl acetal and 4-(1-alkoxy-1-methylethyl)benzaldehyde dimethyl acetal, and intermediates passed through in the process, a hydrolysis step to form the corresponding benzaldehydes and a hydrogenation of this mixture to form 4-isopropylcyclohexylmethanol (IPCHM).
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(2011/09/16)

The catalytic promiscuity of a microbial 7α-hydroxysteroid dehydrogenase. Reduction of non-steroidal carbonyl compounds
A thermostable 7α-hydroxysteroid dehydrogenase from Bacteroides fragilis ATCC 25285 was found to catalyze the reduction of various benzaldehyde analogues to their corresponding benzyl alcohols. The enzyme activity was dependent upon the substituent on the benzene ring of the substrates. Benzaldehydes with electron-withdrawing substituent usually showed higher activity than those with electron-donating groups. Furthermore, this enzyme was tolerant to some organic solvents. These results together with previous studies suggested that 7α-hydroxysteroid dehydrogenase from B. fragilis might play multiple functional roles in biosynthesis and metabolism of bile acids, and in the detoxification of xenobiotics containing carbonyl groups in the large intestine. In addition, its broad substrate spectrum offers great potential for finding applications not only in the synthesis of steroidal compounds of pharmaceutical importance, but also for the production of other high-value fine chemicals.
Liu, Yang,Lv, Tong,Ren, Jie,Wang, Min,Wu, Qiaqing,Zhu, Dunming
experimental part
p. 1136 - 1140
(2011/08/22)

Catalytic activity of iron-substituted polyoxotungstates in the oxidation of aromatic compounds with hydrogen peroxide
The tetrabutylammonium (TBA) salts of Keggin-type polyoxotungstates of the general formula [XW11FeIII(H2O)O39] n-, where X = P, B or Si, were evaluated as catalysts in the oxidation, under mild conditions, of ethylbenzene, cumene, p-cymene and sec-butylbenzene with aqueous H2O2 in CH3CN at 80 °C. The influence of various factors, such as the substrate/catalyst molar ratio, the amount of oxidant added or the reaction time, was investigated in a systematic way. Generally, the system exhibited moderate conversion, with good selectivity towards the corresponding acetophenone and hydroperoxide. In order to understand the reaction pathways, the oxidation of several products and presumed intermediates was also carried out in the presence of TBA 4[PW11Fe(H2O)O39]?2H 2O. Under the conditions used, the oxidation of styrene and styrene derivatives gave rise mainly to carbon-carbon double-bond cleavage, affording the corresponding products in very high yields (81-87%). Possible reaction pathways are presented.
Estrada, Ana C.,Simoes, Mario M. Q.,Santos, Isabel C. M. S.,Neves, M. Graca P. M. S.,Cavaleiro, Jose A. S.,Cavaleiro, Ana M. V.
experimental part
p. 1223 - 1235
(2011/09/12)

Aerobic oxidation of benzylic halides to carbonyl compounds with molecular oxygen catalyzed by tempo/kno2 in aqueous media
Benzylic halides were successfully oxidized to the corresponding aldehydes and ketones in good to excellent yields in aqueous media with molecular oxygen as oxidant in the presence of catalytic amounts of TEMPO (2,2,6,6- tetramethylpiperidyl-1-oxy) and potassium nitrite (KNO2).
Liu, Qifa,Lu, Ming,Yang, Fei,Wei, Wei,Sun, Feng,Yang, Zhenbang,Huang, Sufeng
scheme or table
p. 1106 - 1114
(2010/04/29)

Vanadium hydrogen sulfate (I): Chemoselective trimethylsilylation of alcohols and deprotection of trimethylsilyl ethers
Trimethylsilylation of alcohols with hexamethyldisilazane (HMDS) catalyzed by V(HSO4)3 under mild and completely heterogeneous reaction condition is reported. The method is highly chemoselective for the protection of alcohols in the presence of phenols, amines and thiols. Also, the deprotection of trimethylsilyl ethers is performed in the presence of V(HSO 4)3 at room temperature in good to high yields.
Shirini, Farhad,Zolfigol, Mohammad Ali,Abedini, Masoumeh,Sakhaei, Ali Reza
experimental part
p. 943 - 946
(2009/12/24)

Evolved CYP102A1 (P450BM3) variants oxidise a range of non-natural substrates and offer new selectivity options
The evolution of CYP102A1 variants with enhanced activity and altered specificity characteristics. The Royal Society of Chemistry.
Whitehouse, Christopher J. C.,Bell, Stephen G.,Tufton, Henry G.,Kenny, Richard J. P.,Ogilvie, Lydia C. I.,Wong, Luet-Lok
p. 966 - 968
(2008/09/21)

H3PW12O40 - A selective, environmentally benign, and reusable catalyst for the preparation of methoxymethyl and ethoxymethyl ethers and their deprotections under mild conditions
Different types of primary and secondary alcohols were efficiently transformed to their corresponding methoxymethyl (MOM) and ethoxymethyl (EOM) ethers in the presence of catalytic amounts of H3PW 12O40 at room temperature under solvent-free conditions. Selective protection of primary and secondary alcohols in the presence of phenols and tertiary alcohols was achieved by this method. Deprotection of these ethers to their parent alcohols was also performed using this catalyst in ethanol under reflux conditions. We have also found that primary and secondary MOM- and EOM-ethers are selectively deprotected in the presence of phenolic and tertiary ones, methyl and benzyl ethers, esters, and trimethylsilyl ethers by this catalyst. The notable advantages of this protocol are high yields, short reaction times, easy work-up, non-toxicity, easy availability and handling, eco-friendly, and reusability of the catalyst.
Mohammadpoor-Baltork, Iraj,Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Mirjafari, Arsalan
p. 831 - 840
(2008/12/21)

Desaturation of alkylbenzenes by cytochrome P450BM3 (CYP102A1)
A study was conducted to investigate the desaturation of alkylbenezenes by cytochrome P450BM3 (CYP102A1). It was observed during the study that oxidation of alkylbenzenes with CYP102A1 involves a gamut of P450 activity types that are terminal, sub-terminal benzylic and aromatic hydroxylation; terminal and sub-terminal desaturation; and epoxidation of the olefins. It was also found that the desaturation of cumene by CYP102A1 is sensitive to α-deuteration and insensitive to β-deuteration. Intramolecular deuterium isotope study revealed that the first abstraction in the desaturation of valproic acid and ezlopitant by microsomal P450s take place from activated carbon atoms. The increased β-hydroxylation percentages show that the β-carbon lies closer to the ferryl oxygen in the KT5.
Whitehouse, Christopher J.C.,Bell, Stephen G.,Wong, Luet-Lok
supporting information; scheme or table
p. 10905 - 10908
(2009/11/30)