- Dioxygen activation by siloxide complexes of chromium(II) and chromium(IV)
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The reaction of a tripodal trisilanol with n-butyllithium and CrCl2 results in a dinuclear CrII complex (1), which is capable of cleaving O2 to yield in a unique complex (2) with an asymmetric diamond core composed of two CrIV=O units. Magnetic susceptibility data reveal significant exchange coupling of CrII (S=2) in 1 and large zero-field splitting for CrIV (S=1) in 2 owing to strong spin-orbit coupling of the ground state. The CrIV=O compound can also be generated using PhIO, and evidence was gathered that although it is the stable product isolated after excessive O2 treatment, it further activates O2 to yield an intermediate species that oxidizes THF or Me-THF. By extensive 18O labeling studies we were able to show, that in the course of this process 18O2 exchanges its label with siloxide O atoms of the ligand via terminal oxido ligands.
- Schax, Fabian,Bill, Eckhard,Herwig, Christian,Limberg, Christian
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- Oxidation of tetrahydrofuran to butyrolactone catalyzed by iron-containing clay
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Thermally treated iron-containing clay was used as a greener oxidation catalyst for the conversion of tetrahydrofuran (THF) to butyrolactone (BTL). Mild liquid phase reactions were tested at 50-66 °C using hydrogen peroxide (H2O2) as an oxidizing agent. XRD, TGA, ESR, DR-UV, and FTIR revealed the dislodged iron oxide species formed by treating at ≥500 °C. Formation of active oxidizing species on the surface occurs on contact the dislodged Fe(III) oxide with H2O2. Such active species can promote the oxidation of THF, giving high yield and selectivity of BTL, whereas the iron-containing clay treated at lower temperatures (2O2/THF ratio of 1.0 is sufficient for the production of BTL. Deactivation can be observed presumably due to deposition of the products despite slight leaching of the active iron species.
- Ausavasukhi, Artit,Sooknoi, Tawan
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- Synthesis of functionalized bicyclic imines via intramolecular azide-alkene 1,3-dipolar cycloaddition/intramolecular stork alkylation cascade reaction
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A cascade intramolecular azide-alkene 1,3-dipolar cycloaddition/Stork alkylation reaction has been developed for the synthesis of functionalized cyclic imines with a pyrroline and piperideine structures, employing readily available ω-azidodienes. Copyright
- De Miguel, Irene,Velado, Marina,Herradon, Bernardo,Mann, Enrique
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- Synthetic studies of ingenol: Synthesis of in,out- tricyclo[7.4.1.01,5]tetradecan-14-one
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in,out-Tricyclo[7.4.1.01,5]tetradecan-14-one was synthesized from γ- butyrolactone in 12 steps using ring-closing olefin metathesis as the key step. (C) 2000 Elsevier Science Ltd.
- Kigoshi, Hideo,Suzuki, Yuto,Aoki, Kenta,Uemura, Daisuke
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- Genotoxicity screening for N-nitroso compounds. Electrochemical and electrochemiluminescent detection of human enzyme-generated DNA damage from N-nitrosopyrrolidine
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We report for the first time voltammetric/electrochemiluminescent sensors applied to predict genotoxicity of N-nitroso compounds bioactivated by human cytochrome P450 enzymes. The Royal Society of Chemistry.
- Krishnan, Sadagopan,Hvastkovs, Eli G.,Bajrami, Besnik,Jansson, Ingela,Schenkman, John B.,Rusling, James F.
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- Formal synthesis of optically active ingenol via ring-closing olefin metathesis
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The construction of strained carbon skeletons by ring-closing olefin metathesis (RCM) was investigated. With well-designed diene 4, RCM was found to be applicable to the formation of a highly strained inside-outside bicyclo[4.4.1]undecane skeleton of ingenol, a bioactive diterpenoid, and formal total synthesis of optically active ingenol (1) was achieved. The key features of this synthesis are construction of an A-ring by spirocyclization of the ketone with an allylic chloride unit, 26, and ring closure of a B-ring by olefin metathesis. Starting from Funk's keto ester 6, the key intermediate aldehyde 9 in Winkler's total synthesis was synthesized in eight steps in 12.5% overall yield. This strategy of direct cyclization of a strained inside-outside skeleton provided the first easy access to optically active ingenol.
- Watanabe, Kazushi,Suzuki, Yuto,Aoki, Kenta,Sakakura, Akira,Suenaga, Kiyotake,Kigoshi, Hideo
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- Free-radical approaches to stemoamide and analogues
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(Chemical Equation Presented) Two approaches allowing access to the tricyclic stemona backbone are presented. Both approaches rely on a free-radical cyclization reaction as the key step. In the formal synthesis of (±)-stemoamide, the construction of the A ring of the natural product was achieved via a 5-exo-trig radical cyclization with atom transfer. The two diastereoisomers issuing from this cyclization showed different reactivity while forming the seven-membered ring of the final product. In the second part of this study, a 1-exo-trig free radical cyclization was realized allowing access to the (±)-9,10-bis-epi-stemoamide. This reaction was highly stereoselective and allowed the control of three of the four contiguous stereocenters present in the molecule.
- Bogliotti, Nicolas,Dalko, Peter I.,Cossy, Janine
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- Catalytic behaviour of the Cu(I)/L/TEMPO system for aerobic oxidation of alcohols - a kinetic and predictive model
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Here, we disclose a new copper(i)-Schiff base complex series for selective oxidation of primary alcohols to aldehydes under benign conditions. The catalytic protocol involves 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO), N-methylimidazole (NMI), ambient air, acetonitrile, and room temperature. This system provides a straightforward and rapid pathway to a series of Schiff bases, particularly, the copper(i) complexes bearing the substituted (furan-2-yl)imine bases N-(4-fluorophenyl)-1-(furan-2-yl)methanimine (L2) and N-(2-fluoro-4-nitrophenyl)-1-(furan-2-yl)methanimine (L4) have shown excellent yields. Both benzylic and aliphatic alcohols were converted to aldehydes selectively with 99% yield (in 1-2 h) and 96% yield (in 16 h). The mechanistic studies via kinetic analysis of all components demonstrate that the ligand type plays a key role in reaction rate. The basicity of the ligand increases the electron density of the metal center, which leads to higher oxidation reactivity. The Hammett plot shows that the key step does not involve H-abstraction. Additionally, a generalized additive model (GAM, including random effect) showed that it was possible to correlate reaction composition with catalytic activity, ligand structure, and substrate behavior. This can be developed in the form of a predictive model bearing in mind numerous reactions to be performed or in order to produce a massive data-set of this type of oxidation reaction. The predictive model will act as a useful tool towards understanding the key steps in catalytic oxidation through dimensional optimization while reducing the screening of statistically poor active catalysis.
- Abu-Radaha, Batool,Al-Hunaiti, Afnan,Repo, Timo,Wraith, Darren
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p. 7864 - 7871
(2022/04/09)
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- Synthesis of (E)-α-hydroxyethyl-α,β-unsaturated aldehydes by the reaction of tetrahydrofuran and aromatic aldehydes
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Although α-functionalized α,β-unsaturated aldehydes have important applications in biomedicine, there are few reports on their synthesis. In this article, a new domino reaction for the synthesis of (E)-α-hydroxyethyl-α,β-unsaturated aldehydes was introduced, in which tetrahydrofuran (THF) used as carbonyl block. The first step is an oxidation of THF to 2-hydroxytetrahydrofuran (HTHF) and then it was condensed with ethanolamine under acid catalysis to obtain imine intermediate, which was further isomerized to enamines and used as nucleophiles to attack aldehydes. This is a simple and efficient way for the preparation of (E)-α-hydroxyethyl-α,β-unsaturated aldehydes with notable advantages of a simple procedure, widespread availability of the substrates.
- Shi, Yong-Sen,Liu, Jian-Feng,Wu, Xiao-Lan,Ke, De-Hong,Xu, Sheng
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supporting information
(2021/08/13)
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- Oxidative Cleavage of Indoles Mediated by Urea Hydrogen Peroxide or H2O2 in Polar Solvents
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The oxidative cleavage of indoles (Witkop oxidation) involving the use of H2O2 or urea hydrogen peroxide in combination with a polar solvent has been described. Among these solvents, 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) stands out as the one affording the corresponding 2-ketoacetanilides generally in higher yields The protocol described has also enabled the oxidation of different pyrroles and furans derivatives. Furthermore, the procedure was implemented in a larger-scale and HFIP was distilled from the reaction mixture and reused (up to 4 cycles) without a significant detriment in the reaction outcome, which remarks its sustainability and applicability. (Figure presented.).
- Llopis, Natalia,Gisbert, Patricia,Baeza, Alejandro
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supporting information
p. 3245 - 3249
(2021/06/08)
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- Dual C(sp3)-H Functionalization of Cyclic Ethers via Singlet Oxygen-Mediated Ring Opening and Ring Closing
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A metal-free dual C(sp3)-H bond functionalization of saturated cyclic ethers via photooxidative singlet oxygen-mediated ring opening and ring closing has been developed, providing a method for generating hydrobenzofurans/pyrans/dioxins. Mechanistic studies have confirmed that ring-opening intermediates were effectively generated by singlet oxygen-mediated C(sp3)-H activation and efficiently reacted with aldehydes and activated methylene compounds to form a wide array of products with high diastereoselectivities (up to >95:5 dr). This study is a rare example of α,β-dual C(sp3)-H bond functionalization of ethers.
- Yuan, Xu,Yu, Xianglin,He, Kun,Zhang, Ruihan,Xiao, Weilie,Lin, Jun,Zhan, Zhajun,Cheng, Xiaohong,Shao, Zhihui,Jin, Yi
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supporting information
p. 8267 - 8272
(2021/10/25)
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- Visible light-induced Minisci reaction through photoexcitation of surface Ti-peroxo species
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Photocatalytic Minisci-type functionalization of pyridine with tetrahydrofuran (THF) proceeded using hydrogen peroxide (H2O2) and a TiO2photocatalyst under acidic conditions. Under UV light (λ= 360 nm), the reaction selectivity based on pyridine (Spy) was >99% while the selectivity based on THF (STHF) was low such as 19%. In contrast, under visible light (λ= 400 or 420 nm)Spywas similarly high (>99%) andSTHFwas two times higher than that under UV light. A surface peroxo complex formed upon contact of hydrogen peroxide with the TiO2surface can be selectively photoexcited by visible light to inject the photoexcited electron to the conduction band of TiO2. The electron can reduce H2O2to a reactive oxygen species (ROS) and promote selectively the Minisci-type cross-coupling reaction between pyridinium ions and THF. A reaction test with a hole scavenger (methanol) evidenced that the hole oxidation of H2O2under UV light is responsible for the lower selectivity, in other words, the higher selectivity under visible light would be due to suppression of the hole oxidation of H2O2. These results demonstrate a novel way to improve the selectivity of the photocatalytic cross-coupling reaction by using H2O2as an oxidant with the photoexcitation of surface Ti-peroxo species on TiO2
- Naniwa, Shimpei,Yamamoto, Akira,Yoshida, Hisao
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p. 3376 - 3384
(2021/06/06)
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- Opening the CoIII,IV2(μ-O)2Diamond Core by Lewis Bases Leads to Enhanced C-H Bond Cleaving Reactivity
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The high-valent diiron(IV) intermediate Q is the key oxidant that cleaves strong C-H bonds of methane in the catalytic cycle of soluble methane monooxygenase (sMMO). sMMO-Q was previously reported as a bis-μ-oxo FeIV2(μ-O)2 diamond core but was recently described to have an open core with a long Fe···Fe distance. We recently reported a high-valent CoIII,IV2(μ-O)2 diamond core complex (1) that is highly reactive with sp3 C-H bonds. In this work, we demonstrated that the C-H bond cleaving reactivity of 1 can be further enhanced by introducing a Lewis base X, affording faster kinetic rate constants and the ability to cleave stronger C-H bonds compared to 1. We proposed that 1 first reacts with X in a fast equilibrium to form an open core species X-CoIII-O-CoIV-O (1-X). We were able to characterize 1-X using EPR spectroscopy and DFT calculations. 1-X exhibited an S = 1/2 EPR signal distinct from that of the parent complex 1. DFT calculations showed that 1-X has an open core with the spin density heavily delocalized in the CoIV-O unit. Moreover, 1-X has a more favorable thermodynamic driving force and a smaller activation barrier than 1 to carry out C-H bond activation reactions. Notably, 1-X is at least 4 orders of magnitude more reactive than its diiron open core analogues. Our findings indicate that the diamond core isomerization is likely a practical enzymatic strategy to unmask the strong oxidizing power of sMMO-Q necessary to attack the highly inert C-H bonds of methane.
- Li, Yan,Handunneththige, Suhashini,Xiong, Jin,Guo, Yisong,Talipov, Marat R.,Wang, Dong
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supporting information
(2021/01/11)
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- Production of Hydroxy Acids: Selective Double Oxidation of Diols by Flavoprotein Alcohol Oxidase
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Flavoprotein oxidases can catalyze oxidations of alcohols and amines by merely using molecular oxygen as the oxidant, making this class of enzymes appealing for biocatalysis. The FAD-containing (FAD=flavin adenine dinucleotide) alcohol oxidase from P. chrysosporium facilitated double and triple oxidations for a range of aliphatic diols. Interestingly, depending on the diol substrate, these reactions result in formation of either lactones or hydroxy acids. For example, diethylene glycol could be selectively and fully converted into 2-(2-hydroxyethoxy)acetic acid. Such a facile cofactor-independent biocatalytic route towards hydroxy acids opens up new avenues for the preparation of polyester building blocks.
- Fraaije, Marco W.,Martin, Caterina,Trajkovic, Milos
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p. 4869 - 4872
(2020/02/11)
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- Synthesis and biological testing of ester pheromone analogues for two fruitworm moths (Carposinidae)
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A range of ester pheromone analogues for carposinid moths were synthesized and evaluated for biological activity. The analogues aimed to take advantage of the structural commonality of (7Z)-alken-11-ones found in this family. Analogues were tested on two pest species: Heterocrossa rubophaga and Coscinoptycha improbana. Two of the analogues, (2Z)-nonenyl nonanoate and (4Z)-heptyl undecenoate, elicited significant electroantennogram responses. Only (4Z)-heptyl undecenoate gave consistent responses with both moth species in single sensillum recording. Field trapping trials were conducted with these two analogues both individually and in combination with the pheromone of each of the two moth species. No attraction was observed to either of the analogues alone, by either moth species. However, when (4Z)-heptyl undecenoate was coupled with the pheromone, it produced a strong inhibitory effect in H. rubophaga, reducing male moth trap catch by over 95%. No inhibitory effect on male moth trap catch was observed in C. improbana.
- Barker, David,Chhagan, Asha,Park, Kye Chung,Pilkington, Lisa I.,Suckling, David M.,Twidle, Andrew M.
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p. 9557 - 9567
(2020/10/13)
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- Hydrogenative metathesis of enynes via piano-stool ruthenium carbene complexes formed by alkyne gem-hydrogenation
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The only recently discovered gem-hydrogenation of internal alkynes is a fundamentally new transformation, in which both H atoms of dihydrogen are transferred to the same C atom of a triple bond while the other position transforms into a discrete metal carbene complex. [Cp?RuCl]4 is presently the catalyst of choice: the resulting piano-stool ruthenium carbenes can engage a tethered alkene into either cyclopropanation or metathesis, and a prototypical example of such a reactive intermediate with an olefin ligated to the ruthenium center has been isolated and characterized by X-ray diffraction. It is the substitution pattern of the olefin that determines whether metathesis or cyclopropanation takes place: a systematic survey using alkenes of largely different character in combination with a computational study of the mechanism at the local coupled cluster level of theory allowed the preparative results to be sorted and an intuitive model with predictive power to be proposed. This model links the course of the reaction to the polarization of the double bond as well as to the stability of the secondary carbene complex formed, if metathesis were to take place. The first application of "hydrogenative metathesis"to the total synthesis of sinularones E and F concurred with this interpretation and allowed the proposed structure of these marine natural products to be confirmed. During this synthesis, it was found that gem-hydrogenation also provides opportunities for C-H functionalization. Moreover, silylated alkynes are shown to participate well in hydrogenative metathesis, which opens a new entry into valuable allylsilane building blocks. Crystallographic evidence suggests that the polarized [Ru-Cl] bond of the catalyst interacts with the neighboring R3Si group. Since attractive interligand Cl/R3Si contacts had already previously been invoked to explain the outcome of various ruthenium-catalyzed reactions, including trans-hydrosilylation, the experimental confirmation provided herein has implications beyond the present case.
- Peil, Sebastian,Bistoni, Giovanni,Goddard, Richard,Fürstner, Alois
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supporting information
p. 18541 - 18553
(2020/11/17)
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- Surface Modification of Two-Dimensional Metal–Organic Layers Creates Biomimetic Catalytic Microenvironments for Selective Oxidation
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Microenvironments in enzymes play crucial roles in controlling the activities and selectivities of reaction centers. Herein we report the tuning of the catalytic microenvironments of metal–organic layers (MOLs), a two-dimensional version of metal–organic frameworks (MOFs) with thickness down to a monolayer, to control product selectivities. By modifying the secondary building units (SBUs) of MOLs with monocarboxylic acids, such as gluconic acid, we changed the hydrophobicity/hydrophilicity around the active sites and fine-tuned the selectivity in photocatalytic oxidation of tetrahydrofuran (THF) to exclusively afford butyrolactone (BTL), likely a result of prolonging the residence time of reaction intermediates in the hydrophilic microenvironment of catalytic centers. Our work highlights new opportunities in using functional MOLs as highly tunable and selective two-dimensional catalytic materials.
- Shi, Wenjie,Cao, Lingyun,Zhang, Hua,Zhou, Xin,An, Bing,Lin, Zekai,Dai, Ruihan,Li, Jianfeng,Wang, Cheng,Lin, Wenbin
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supporting information
p. 9704 - 9709
(2017/08/08)
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- Preparation of Highly Active Monometallic Rhenium Catalysts for Selective Synthesis of 1,4-Butanediol from 1,4-Anhydroerythritol
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1,4-Butanediol can be produced from 1,4-anhydroerythritol through the co-catalysis of monometallic mixed catalysts (ReOx/CeO2+ReOx/C) in the one-pot reduction with H2. The highest yield of 1,4-butanediol was over 80 %, which is similar to the value obtained over ReOx–Au/CeO2+ReOx/C catalysts. Mixed catalysts of CeO2+ReOx/C showed almost the same performance, giving 89 % yield of 1,4-butanediol. The reactivity trends of possible intermediates suggest that the reaction mechanism over ReOx/CeO2+ReOx/C is similar to that over ReOx–Au/CeO2+ReOx/C: deoxydehydration (DODH) of 1,4-anhydroerythritol to 2,5-dihydrofuran over ReOx species on the CeO2 support with the promotion of H2 activation by ReOx/C, isomerization of 2,5-dihydrofuran to 2,3-dihydrofuran catalyzed by ReOx on the C support, hydration of 2,3-dihydrofuran catalyzed by C, and hydrogenation to 1,4-butanediol catalyzed by ReOx/C. The reaction order of conversion of 1,4-anhydroerythritol with respect to H2 pressure is almost zero and this indicates that the rate-determining step is the formation of 2,5-dihydrofuran from the coordinated substrate with reduced Re in the DODH step. The activity of ReOx/CeO2+ReOx/C is higher than that of ReOx–Au/CeO2+ReOx/C, which is probably related to the reducibility of ReOx/C and the mobility of the Re species between the supports. High-valent Re species such as Re7+ on the CeO2 and C supports are mobile in the solvent; however, low-valent Re species, including metallic Re species, have much lower mobility. Metallic Re and cationic low-valent Re species with high reducibility and low mobility can be present on the carbon support as a trigger for H2 activation and promoter of the reduction of Re species on CeO2. The presence of noble metals such as Au can enhance the reducibility through the activation of H2 molecules on the noble metal and the formation of spilt-over hydrogen over noble metal/CeO2, as indicated by H2 temperature-programmed reduction. The higher reducibility of ReOx–Au/CeO2 lowers the DODH activity of ReOx–Au/CeO2+ReOx/C in comparison with ReOx/CeO2+ReOx/C by restricting the movement of Re species from C to CeO2.
- Wang, Tianmiao,Tamura, Masazumi,Nakagawa, Yoshinao,Tomishige, Keiichi
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p. 3615 - 3626
(2019/07/15)
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- Hydrogenative Cyclopropanation and Hydrogenative Metathesis
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The unusual geminal hydrogenation of a propargyl alcohol derivative with [CpXRuCl] as the catalyst entails formation of pianostool ruthenium carbenes in the first place; these reactive intermediates can be intercepted with tethered alkenes to give either cyclopropanes or cyclic olefins as the result of a formal metathesis event. The course of the reaction is critically dependent on the substitution pattern of the alkene trap.
- Peil, Sebastian,Guthertz, Alexandre,Biberger, Tobias,Fürstner, Alois
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supporting information
p. 8851 - 8856
(2019/05/28)
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- Bimetallic Synergy Effects of Phyllosilicate-Derived NiCu@SiO2 Catalysts for 1,4-Butynediol Direct Hydrogenation to 1,4-Butanediol
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Hydrogenation of 1,4-butynediol (BYD) to 1,4-butanediol (BDO) is a two-step process, with an initial hydrogenation of BYD to 1,4-butenediol (BED) and the subsequent hydrogenation of BED to BDO. However, the BYD hydrogenation also involves many side reactions originated from the isomerization of BED. In order to inhibit the isomerization pathways, phyllosilicate-derived bimetallic NiCu@SiO2 catalysts have been developed for efficient C≡C/C=C hydrogenation in this work. Due to the formation of phyllosilicate matrix and highly dispersed metal nanoparticles, NiCu@SiO2 showed total BYD conversion with extremely high BDO selectivity compared to a conventional impregnated Ni/SiO2 catalyst. A remarkable result of NiCu@SiO2 catalysts is that a new type of bimetallic catalytic sites responsible for the high hydrogenation activity can be differentiated from the Ni phyllosilicate matrix by the induction of Cu species, and these neighboring bimetallic sites with the help of weak acid phyllosilicate interface, can realize to stabilize the activated BED species (allyl alcohol form) adsorbed on the cooperative active sites, thus to avoid its isomerization to aldehyde form and unexpected C=O hydrogenolysis. Consequently, it enhanced the selectivity to the diol products BDO significantly. Owing to the benign improvement of three center synergy effect, 9Ni1Cu@SiO2 possesses the optimum BYD direct hydrogenation ability with a rarely reported high selectivity of 90.5–94.5 % at 50 °C and 1 MPa.
- Wang, Changzhen,Tian, Yani,Wu, Ruifang,Li, Haitao,Yao, Benzhen,Zhao, Yongxiang,Xiao, Tiancun
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p. 4777 - 4787
(2019/08/26)
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- Transfer Hydrogenation of Carbon Dioxide to Methanol Using a Molecular Ruthenium-Phosphine Catalyst
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Transfer hydrogenation using molecular catalysts has become a powerful tool in synthetic chemistry and a wide range of unsaturated substrates can be reduced with this protocol. Whereas reactions using iso-propanol as hydrogen donor are already well established, recent examples demonstrate the possibility to use linear alcohols from renewable resources. Herein, the first effective transfer hydrogenation of the challenging substrate carbon dioxide (CO2) directly to methanol is described, applying a molecular ruthenium catalyst and linear alcohols as the hydrogen source. In neat ethanol, TONs up to 121 are achieved under moderate pressures of CO2. Moreover, systematic investigations enable to propose initial acceptorless dehydrogenation of the alcohol, followed by the reduction of CO2 to methanol via ethyl formate, as mechanistic basis.
- Westhues, Niklas,Klankermayer, Jürgen
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p. 3371 - 3375
(2019/07/12)
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- A long-range tautomeric effect on a new Schiff isoniazid analogue, evidenced by NMR study and X-ray crystallography
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Long-range tautomerism to a N,O-aminal thereby closing a tetrahydrofuran ring was evidenced for an isoniazid analogue, whose accidental synthesis is presented in the paper. The isoniazid analogue was synthesized by the reaction of isoniazid with 2-hydroxy-tetrahydrofuran which was demonstrated to exist in old THF together with other peroxides, especially 2-HOO-THF. The same compound was efficiently obtained from a THF containing 2-HOO-THF, by reducing this peroxide in the presence of isoniazid. The 2,4-dinitrophenylhydrazone was also synthesized. The oxidation of 1,4-butanediol and the reaction of the resulting mono-aldehyde with isoniazid gave the same compound. The existence of the linear tautomer was evidenced in the NMR spectra in DMSO-d6 and was confirmed by X-ray analysis to be the single tautomer in the crystal. The cyclic N,O-aminal tautomer was found in the NMR spectra in CDCl3, resulting from an intramolecular HCl-catalyzed addition of the hydroxyl group to the double bond CHN of the linear tautomer, thereby closing a tetrahydrofuran ring. This is a favoured cyclization according to Baldwin's rules (5-exo-trig). The same tautomerism was also present for two isoniazid analogues obtained from two lactols, used in prostaglandin synthesis. The compounds 1, 4, 6 and INH had no antibacterial or antifungal activity.
- Tǎnase, Constantin I.,Drǎghici, Constantin,Shova, Sergiu,Hanganu, Anamaria,Gal, Emese,Munteanu, Cristian V. A.
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p. 14459 - 14468
(2018/08/29)
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- Production of 1,5-pentanediol via upgrading of tetrahydrofurfuryl alcohol
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A method of making 1,5-pentanediol from tetrahydrofurfural alcohol. The method includes the steps of dehydrating tetrahydrofurfural alcohol (THFA) to dihydropyran (DHP); hydrating at least a portion of the DHP to 2-hydroxy-tetrahydropyran (2-HY-THP) in the presence of a solid acid catalyst; and hydrogenating at least a portion of the 2-HY-THP to 1,5-pentanediol. The method can be conducted entirely in the absence of noble metal catalysts.
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Page/Page column 23
(2018/10/11)
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- Facile Conversion of α-Acyloxy Amides into 3-Hydroxy-lactams
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The new synthetic route to α-acyloxy amides based on Passerini multicomponent reaction followed by transformation into the corresponding five-, six-, and seven-membered 3-hydroxy-lactams has been proposed. The influence of the reaction conditions, which includes substrate structure on the reaction course that led to desired lactams, was studied. The use of various oxo components in the Passerini multicomponent reaction (P-MCR) has been evaluated. The first example of a semicyclic O,O-acetal employed as an aldehyde equivalent in the P-MCR has been reported. Finally, the established protocol was successfully applied for the enantioselective synthesis of 3-hydroxy-lactams, which play a crucial role in the synthesis of the number of bioactive compounds.
- Koszelewski, Dominik,Trzepizur, Damian,Zaorska, Ewelina,Madej, Arleta,Brodzka, Anna,Paprocki, Daniel,Borys, Filip,Wilk, Monika,Ostaszewski, Ryszard
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p. 3280 - 3290
(2018/07/13)
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- One-pot catalytic selective synthesis of 1,4-butanediol from 1,4-anhydroerythritol and hydrogen
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A physical mixture of ReOx-Au/CeO2 and carbon-supported rhenium catalysts effectively converted 1,4-anhydroerythritol to 1,4-butanediol with H2 as a reductant. The combination of these two catalysts in a one-pot reaction dramatically increased the selectivity of 1,4-butanediol as well as the conversion of 1,4-anhydroerythritol. The yield of 1,4-butanediol reached ～90%, which is the highest yield from erythritol and 1,4-anhydroerythritol so far, furthermore, at a relatively low reaction temperature of 413 K. This reaction involves the ReOx-Au/CeO2-catalyzed deoxydehydration of 1,4-anhydroerythritol to 2,5-dihydrofuran and ReOx/C-catalyzed successive isomerization, hydration and reduction reactions of 2,5-dihydrofuran.
- Wang, Tianmiao,Liu, Sibao,Tamura, Masazumi,Nakagawa, Yoshinao,Hiyoshi, Norihito,Tomishige, Keiichi
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supporting information
p. 2547 - 2557
(2018/06/18)
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- Synthesis of (4: E,6 Z,10 Z)-hexadeca-4,6,10-trien-1-ol and (4 E,6 E,10 Z)-hexadeca-4,6,10-trien-1-ol, the pheromone components of cocoa pod borer moth Conopomorpha cramerella
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A concise and efficient synthesis of the pheromone components of the cocoa pod borer moth, namely (4E,6Z,10Z)-hexadeca-4,6,10-trien-1-ol and (4E,6E,10Z)-hexadeca-4,6,10-trien-1-ol, starting from commercially available materials, was reported. The overall yield was 30.4% and 27.4%, respectively. The stereoselective formation of (E,Z)- or (E,E)-conjugated double bond relied on Sonogashira coupling with (E)-5-bromopent-4-en-1-ol prepared from (E)-5-bromopent-4-enal and the stereoselective hydrogenation of the enyne, while the 10Z-double bond was formed by Wittig reaction from 4-hydroxybutanal and n-hexyltriphenylphosphonium bromide.
- Huang, Fei,Zhang, Yushun,Yao, Yun,Yang, Wanqiu,Tao, Yunhai
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p. 35575 - 35580
(2017/07/28)
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- A 4 - amino - 1 - butanol synthetic method
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The invention discloses a synthetic method of 4-animo-1-butanol. The synthetic method is characterized by comprising the following steps: reacting a raw material A in an acid solution to obtain an intermediate product B, carrying out contact reaction on the intermediate product B and a raw material C in the presence of alkaline substances to obtain an intermediate product D, and transforming the intermediate product D into the target product, namely 4-animo-1-butanol, in the presence of a reducing agent. The synthetic method is suitable for large-scale synthesis, synthesis steps are short, and the operation is convenient.
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Paragraph 0043-0046
(2018/11/04)
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- Comparison of “on water” and solventless procedures in the rhodium-catalyzed hydroformylation of diolefins, alkynes, and unsaturated alcohols
-
Catalytic systems containing Rh(acac)(CO)2 or Rh/PAA (PAA?=?polyacrylic acid) and hydrophobic phosphine (PPh3) were used in the hydroformylation of diolefins, alkynes, and unsaturated alcohols under solventless and “on water” conditions. The total yield of dialdehydes obtained from 1,5-hexadiene and 1,7-octadiene reached 99%, and regioselectivity towards linear dialdehydes was higher in the “on water” system. The tandem hydroformylation-hydrogenation of phenylacetylene led to the formation of saturated aldehydes (3-phenylpropanal and 2-phenylpropanal) at 98% conversion with a good regioselectivity towards the linear aldehyde in the “on water” reaction. In contrast, solventless conditions appeared better in the hydroformylation of 1-propen-3-ol. 4-Hydroxybutanal, formed in this reaction with an excellent selectivity, was next transformed to tetrahydrofuran-2-ol via a ring-closure process. Cyclic products were also obtained in hydroformylation of 1-buten-3-ol. In reaction of undec-1-ol and 2-allylphenol linear aldehydes were formed with the yield 69–87%. The hydroformylation of 3-buten-1-ol performed under “on water” conditions showed very good regioselectivity towards a linear aldehyde, 5-hydroxypentanal. Further cyclization of the aldehyde to tetrahydropyran-2-ol was observed.
- Alsalahi,Trzeciak
-
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- Iron(II) catalysis in oxidation of hydrocarbons with ozone in acetonitrile
-
Oxidation of alcohols, ethers, and sulfoxides by ozone in acetonitrile is catalyzed by submillimolar concentrations of Fe(CH3CN)62+. The catalyst provides both rate acceleration and greater selectivity toward the less oxidized products. For example, Fe(CH3CN)62+-catalyzed oxidation of benzyl alcohol yields benzaldehyde almost exclusively (>95%), whereas the uncatalyzed reaction generates a 1:1 mixture of benzaldehyde and benzoic acid. Similarly, aliphatic alcohols are oxidized to aldehydes/ketones, cyclobutanol to cyclobutanone, and diethyl ether to a 1:1 mixture of ethanol and acetaldehyde. The kinetics of oxidation of alcohols and diethyl ether are first-order in [Fe(CH3CN)62+] and [O3] and independent of [substrate] at concentrations greater than ～5 mM. In this regime, the rate constant for all of the alcohols is approximately the same, kcat = (8 ± 1) × 104 M-1 s-1, and that for (C2H5)2O is (5 ± 0.5) × 104 M-1 s-1. In the absence of substrate, Fe(CH3CN)62+ reacts with O3 with kFe = (9.3 ± 0.3) × 104 M-1 s-1. The similarity between the rate constants kFe and kcat strongly argues for Fe(CH3CN)62+/O3 reaction as rate-determining in catalytic oxidation. The active oxidant produced in Fe(CH3CN)62+/O3 reaction is suggested to be an Fe(IV) species in analogy with a related intermediate in aqueous solutions. This assignment is supported by the similarity in kinetic isotope effects and relative reactivities of the two species toward substrates.
- Bataineh, Hajem,Pestovsky, Oleg,Bakac, Andreja
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p. 1629 - 1637
(2015/03/14)
-
- Cu-catalyzed oxidative Povarov reactions between N-alkyl N-methylanilines and saturated oxa- and thiacycles
-
Cu-catalyzed oxidative Povarov reactions between N,N-dialkylanilines and saturated oxa- or thiacycles with tert-butyl hydroperoxide (TBHP) are described; notably, the reactions use neither [4π] nor [2π]-motifs as the initial reagents. The use of cheap alkane-based substances as building units is of mechanistic and practical interest as two inert sp3 C-H bonds are activated.
- Kawade, Rahul Kisan,Huple, Deepak B.,Lin, Rong-Jing,Liu, Rai-Shung
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p. 6625 - 6628
(2015/04/14)
-
- Process for treating homoserin compounds
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The present invention relates to the preparation of a useful compound which can be used as an intermediate product for preparing an important compound in the industrial field from a homoserine-based compound and provides a process for treating a homoserine-based compound, capable of simply mass producing a useful compound from a homoserine-based compound with excellent efficiency.(AA) Homoserine-based compound(BB) Product(CC) GBL derivative(DD) Halo-GBL(EE, FF, GG) GBL puranone(HH) Puranone(II) Dialkyl succinate(JJ) Step 1(KK) Step 2(LL) Step 3(MM) Step 4(NN) Step 5(OO) Step 6(PP) Step 7COPYRIGHT KIPO 2016
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-
Paragraph 0223; 0227-0227; 0238-0241
(2017/01/02)
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- Highly functionalized and potent antiviral cyclopentane derivatives formed by a tandem process consisting of organometallic, transition-metal-catalyzed, and radical reaction steps
-
A simple modular tandem approach to multiply substituted cyclopentane derivatives is reported, which succeeds by joining organometallic addition, conjugate addition, radical cyclization, and oxygenation steps. The key steps enabling this tandem process are the thus far rarely used isomerization of allylic alkoxides to enolates and single-electron transfer to merge the organometallic step with the radical and oxygenation chemistry. This controlled lineup of multiple electronically contrasting reactive intermediates provides versatile access to highly functionalized cyclopentane derivatives from very simple and readily available commodity precursors. The antiviral activity of the synthesized compounds was screened and a number of compounds showed potent activity against hepatitisC and dengue viruses.
- Jagtap, Pratap R.,Ford, Leigh,Deister, Elmar,Pohl, Radek,Cisarova, Ivana,Hodek, Jan,Weber, Jan,Mackman, Richard,Bahador, Gina,Jahn, Ullrich
-
supporting information
p. 10298 - 10304
(2014/08/18)
-
- Cascade Michael addition/cycloketalization of cyclic 1,3-dicarbonyl compounds: Important role of the tethered alcohol of α,β-unsaturated carbonyl compounds on reaction rate and regioselectivity
-
Reactions of α,β-unsaturated aldehydes and cyclic 1,3-dicarbonyl compounds proceed primarily by cascade Knoevenagel condensation/six-π-electron electrocyclization (K6EC, formal [3 + 3] cycloaddition), while α,β-unsaturated ketones usually react with cyclic 1,3-dicarbonyl compounds in a 1,4-addition manner. This paper discloses our findings that under acidic conditions, α,β-unsaturated carbonyl compounds (ketones and aldehydes) with a tethered alcohol react with cyclic 1,3-dicarbonyl compounds in a highly regioselective 1,4-addition fashion via in situ generation of a hypothetical α-methylene cyclic oxonium ion as the reactive Michael acceptor. Our studies uncovered the important effect of the tethered alcohol on the reaction rate and/or efficiency and some new mechanistic aspects of the cascade Michael addition/cycloketalization. Finally, the substrate scope was examined, and 43 analogues of penicipyrone and tenuipyrone were prepared in good to excellent yields.
- Yao, Hongliang,Song, Liyan,Liu, Yuan,Tong, Rongbiao
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p. 8774 - 8785
(2015/01/09)
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- Raney Ni-Si catalysts for selective hydrogenation of highly concentrated 2-butyne-1,4-diol to 2-butene-1,4-diol
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Raney Ni-Si catalysts were synthesized by treating Raney Ni with silane in a fluidized bed reactor and tested in the selective hydrogenation of 2-butyne-1,4-diol (BYD) at high concentration. Structural characterizations including XRD patterns, TEM images, and X-ray photoelectron spectroscopy show that Raney Ni-Si catalysts are composed of a Ni core surrounded by nickel silicides. These species transform from Ni-rich silicide (Ni2Si) to Si-rich silicide (NiSi2) with increasing silicification temperature from 250 °C to 450 °C. The insertion of Si atoms into Raney Ni catalysts decreased the catalytic activity, but significantly improved the selectivity to 2-butene-1,4-diol (BED). The beneficial effect of Si on the selectivity hydrogenation of BYD may be caused by the presence of Si at Ni-defect sites, and the formation of the surface nickel silicide that suppress the further hydrogenation of BED. Compared with the traditional Lindlar-type catalysts, such Raney Ni-Si materials can be used extensively in organic synthesis for selective hydrogenation of alkynes, avoiding the associated hazards of toxic additives.
- Chen, Xiao,Zhang, Mingming,Yang, Kaixuan,Williams, Christopher T.,Liang, Changhai
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p. 1118 - 1126
(2014/07/21)
-
- METHOD FOR PRODUCING HYDRIDE USING UNSATURATED COMPOUND HAVING CARBON NUMBER OF 4 AS RAW MATERIAL
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The present invention relates to a method for producing a hydride having a carbon number of 4, comprising contacting, in liquid phase, an unsaturated compound having a carbon number of 4 as a raw material with a solid catalyst obtained by loading a metal element belonging to Groups 9 to 11 of the long periodic table on a support, thereby performing hydrogenation to produce a corresponding hydride having a carbon number of 4, wherein hydrogenation is performed in the presence of, as a solvent, a 1,4-butanediol having a nitrogen component concentration of 1 ppm by weight to 1 wt % in terms of nitrogen atom.
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-
Paragraph 0067-0069
(2014/05/20)
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- A powerful hydrogen-bond-donating organocatalyst for the enantioselective intramolecular oxa-michael reaction of α,β-unsaturated amides and esters
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Tuning the organocatalyst: An unprecedented enantioselective intramolecular oxa-Michael reaction of unactivated α,β-unsaturated amides and esters catalyzed by a powerful hydrogen-bond-donating organocatalyst has been developed. Furthermore, the products obtained from this reaction have been used for the straightforward asymmetric synthesis of several natural products and biologically important compounds. Copyright
- Kobayashi, Yusuke,Taniguchi, Yamato,Hayama, Noboru,Inokuma, Tsubasa,Takemoto, Yoshiji
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supporting information
p. 11114 - 11118
(2013/10/22)
-
- Mechanistic investigations of the ZnCl2-mediated tandem Mukaiyama aldol lactonization: Evidence for asynchronous, concerted transition states and discovery of 2-oxopyridyl ketene acetal variants
-
The ZnCl2-mediated tandem Mukaiyama aldol lactonization (TMAL) reaction of aldehydes and thiopyridyl ketene acetals provides a versatile, highly diastereoselective approach to trans-1,2-disubstituted β-lactones. Mechanistic and theoretical studies described herein demonstrate that both the efficiency of this process and the high diastereoselectivity are highly dependent upon the type of ketene acetal employed but independent of ketene acetal geometry. Significantly, we propose a novel and distinct mechanistic pathway for the ZnCl2-mediated TMAL process versus other Mukaiyama aldol reactions based on our experimental evidence to date and further supported by calculations (B3LYP/BSI). Contrary to the commonly invoked mechanistic extremes of [2+2] cycloaddition and aldol lactonization mechanisms, investigations of the TMAL process suggest a concerted but asynchronous transition state between aldehydes and thiopyridyl ketene acetals. These calculations support a boat-like transition state that differs from commonly invoked Mukaiyama "open" or Zimmerman-Traxler "chair-like" transition-state models. Furthermore, experimental studies support the beneficial effect of pre-coordination between ZnCl2 and thiopyridyl ketene acetals prior to aldehyde addition for optimal reaction rates. Our previously proposed, silylated β-lactone intermediate that led to successful TMAL-based cascade sequences is also supported by the described calculations and ancillary experiments. These findings suggested that a similar TMAL process leading to β-lactones would be possible with an oxopyridyl ketene acetal, and this was confirmed experimentally, leading to a novel TMAL process that proceeds with efficiency comparable to that of the thiopyridyl system.
- Zhao, Cunxiang,Mitchell, T. Andrew,Vallakati, Ravikrishna,Perez, Lisa M.,Romo, Daniel
-
supporting information; experimental part
p. 3084 - 3094
(2012/04/10)
-
- Catalytic oxidation of cyclic ethers to lactones over various titanosilicates
-
Various crystalline microporous metallosilicates have been used in the liquid phase catalytic oxidation of different cyclic ethers into their corresponding lactones in the presence of dilute aqueous H2O 2 as oxidant. Among the various metallosilicates studied for the oxidation of tetrahydrofuran to γ-butyrolactone, titanosilicates exhibited the best activity than the other metallosilicates such as chromium silicalite-1 (CrS-1), chromium silicalite-2 (CrS-2) and vanadium silicalite-1 (VS-1). The intrinsic activity of TS-1 was found to be marginally higher than the other titanosilicates. Cyclic ethers undergo αC-H oxidation to give the corresponding lactones; whereas open-chain ether produce carboxylic acids by initial αC-H bond oxidation to give ester as an intermediate product, which further undergoes cleavage of -O- linkage to give the final carboxylic acids. The conversion of substituted tetrahydrofuran is decreased with number of -CH3 groups at α- and/or β-position. The lactone formation is hindered when both the α-positions are substituted with methyl substituents. Mechanistically, titanium hydroperoxo complex formed in the titanosilicate/H2O2/H2O system is believed to oxidize the αC-H bond of ethers producing the respective α-hydroxylated product, which undergoes further oxidation to give the lactones (for cyclic ethers) or carboxylic acids (for open-chain ethers).
- Sasidharan, Manickam,Bhaumik, Asim
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experimental part
p. 105 - 110
(2011/05/04)
-
- METHOD FOR PRODUCING VINYL ETHER COMPOUND
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The invention provides a method for producing a vinyl ether compound, characterized in that the method includes isomerizing an allyl ether compound represented by formula (I) or (II): (wherein R1 represents a C1 to C6 alkyl group; each of R2, R3, and R4 independently represents a hydrogen atom, a C1 to C6 alkyl group, or a C3 to C6 alkenyl group; and n is 1 or 2) in the presence of hydrogen, a monodentate tris(ortho-substituted aryl) phosphite, and a rhodium compound. The vinyl ether compound is useful as a raw material, an intermediate, etc. for producing pharmaceuticals, agrochemicals, polymers, etc.
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Page/Page column 9-10
(2011/02/19)
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- Aerial oxidation of tetrahydrofuran to 2-hydroxotetrahydrofuran in the presence of a trimeric CuI complex [Cu3L3] (HL = tBuNHC(S)NHP(S)(OiPr)2) and trapping of the unstable product at recrystallization
-
The reaction of the potassium salt of N-thiophosphorylated thiourea tBuNHC(S)NHP(S)(OiPr)2 (HL) with Cu(NO3)2 in aqueous EtOH leads to the trinuclear [Cu3(tBuNHC(S)NP(S)(OiPr) 2-S,S′)3] ([Cu3L3]) complex. It was established that [Cu3L3] provokes the aerobic oxidation of tetrahydrofuran to 2-hydroxotetrahydrofuran and traps the latter at crystallization. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
- Luckay, Robert C.,Sheng, Xia,Strasser, Christoph E.,Raubenheimer, Helgard G.,Safin, Damir A.,Babashkina, Maria G.,Klein, Axel
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supporting information; scheme or table
p. 2835 - 2840
(2011/02/27)
-
- Highly diastereoselective synthesis of substituted pyrrolidines using a sequence of azomethine ylide cycloaddition and nucleophilic cyclization
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(Figure Presented) Although cycloadditions of azomethine ylides usually give mixtures of endolexo adducts, we successfully tuned the mechanistic path of a new reaction cascade to afford substituted pyrrolidines In high yields and diastereomeric purity. This was achieved by forcing the demetalation of tin- or silicon-substituted iminium Ions, followed by azomethine ylide cycloaddition and nucleophilic cyclization. Structural complexity is thus built rapidly In a fully controlled one-pot reaction cascade.
- Belanger, Guillaume,Darsigny, Veronique,Dore, Michael,Levesque, Francois
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supporting information; scheme or table
p. 1396 - 1399
(2010/06/15)
-
- Intramolecular [1 + 4 + 1] cycloaddition: Establishment of the method
-
Structurally complex and physiologically active natural products often include bicyclic and polycyclic ring systems having defined relative and absolute configuration. Approaches that allow the construction of more than one carbocyclic ring at a time have proven valuable, in particular those that allow at the same time the control of an array of new stereogenic centers. One of the most general and most widely used protocols has been the intramolecular Diels-Alder [4 + 2] cycloaddition, in which a single stereogenic center between the diene and the dienophile can control the relative and absolute configuration of the product. We report a two-step [1 + 4 + 1] procedure for bicyclic and polycyclic construction, based on the cyclization of an ω-dienyl ketone. This is complementary to, and will likely be as useful as, the intramolecular Diels-Alder cycloaddition.
- Taber, Douglass F.,Guo, Pengfei,Guo, Na
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supporting information; experimental part
p. 11179 - 11182
(2010/10/04)
-
- A regio- and diastereoselective intramolecular nitrone cycloaddition for practical 3- and 2,3-disubstituted piperidine synthesis from γ-butyrolactone
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(Chemical Equation Presented) A fast and efficient route for diversity-oriented synthesis of 3- and 2,3-disubstituted piperidines, featuring an intramolecular nitrone cycloaddition with high regio- and diastereoselectivity, was achieved in six steps and 36-66% overall yield from commercially available γ-butyrolactone or 1,4-butanediol. A new N-alkenyl nitrone enoate was used in this intramolecular nitrone cycloaddition, and the regioselectivity, diastereoselectivity, and reversibility of this cycloaddition were investigated.
- Stephens, Benjamin E.,Liu, Fei
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supporting information; experimental part
p. 254 - 263
(2009/04/10)
-
- Process for preparing Estrogen-antagonistic 11 beta-Fluoro-17alpha-alkylestra-1,3,5(10)-triene-3,17-diols having a 7alpha-(xi-Alkylamino-omega-perfluoroalkyl)alkyl side chain and alpha-Alkyl(amino)-omega-perfluoro(alkyl)alkanes and Processes for their Preparation
-
The present invention relates to a new process for preparing estrogen-antagonistic 11β-fluoro-17α-alkylestra-1,3,5(10)-triene-3,17-diols of the general formula I having a 7α-(ξ-alkylamino-ω-perfluoroalkyl)alkyl side chain and to α-alkyl(amino)-ω-perfluoro(alkyl)alkanes of the general formula II, to processes for their preparation and to the intermediates required for this purpose.
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Page/Page column 5-6
(2009/04/24)
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- Aliphatic C-H bond activation initiated by a (μ-η2: η2-peroxo)dicopper(II) complex in comparison with cumylperoxyl radical
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A (μ-η2:η2-peroxo)dicopper(II) complex, [Cu2(H-L)(O2)]2+ (1-O2), supported by the dinucleating ligand 1,3-bis[bis(6-methyl-2-pyridylmethyl)aminomethyl] benzene (H-L) is capable of initiating C-H bond activation of a variety of external aliphatic substrates (SHn): 10-methyl-9,10-dihydroacridine (AcrH2), 1,4-cyclohexadiene (1,4-CHD), 9,10-dihydroanthracene (9,10-DHA), fluorene, tetralin, toluene, and tetrahydrofuran (THF), which have C-H bond dissociation energies (BDEs) ranging from ～75 kcal mol-1 for 1,4-CHD to ～92 kcal mol-1 for THF. Oxidation of SH n afforded a variety of oxidation products, such as dehydrogenation products (SH(n-2)), hydroxylated and further-oxidized products (SH(n-1)OH and SH(n-2)=O), dimers formed by coupling between substrates (H(n-1)S-SH(n-1)) and between substrate and H-L (H-L-SH(n-1)). Kinetic studies of the oxidation of the substrates initiated by 1-O2 in acetone at -70°C revealed that there is a linear correlation between the logarithms of the rate constants for oxidation of the C-H bonds of the substrates and their BDEs, except for THF. The combination of this correlation and the relatively large deuterium kinetic isotope effects (KIEs), k2H/k2D (13 for 9,10-DHA, ?29 for toluene, and ～34 for THF at -70°C and ～9 for AcrH2 at -94°C) indicates that H-atom transfer (HAT) from SHn (SDn) is the rate-determining step. Kinetic studies of the oxidation of SHn by cumylperoxyl radical showed a correlation similar to that observed for 1-O2, indicating that the reactivity of 1-O2 is similar to that of cumylperoxyl radical. Thus, 1-O 2 is capable of initiating a wide range of oxidation reactions, including oxidation of aliphatic C-H bonds having BDEs from ～75 to ～92 kcal mol-1, hydroxylation of the m-xylyl linker of H-L, and epoxidation of styrene (Matsumoto, T.; et al. J. Am. Chem. Soc. 2006, 128, 3874).
- Matsumoto, Takahiro,Ohkubo, Kei,Honda, Kaoru,Yazawa, Akiko,Furutachi, Hideki,Fujinami, Shuhei,Fukuzumi, Shunichi,Suzuki, Masatatsu
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experimental part
p. 9258 - 9267
(2009/12/06)
-
- Carbon dioxide induced phase switching for homogeneous-catalyst recycling
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SwitchPhos: Rhodium complexes formed from PPh3 ligands functionalized with weakly basic amidine groups are highly active catalysts for the hydroformylation of alkenes. On bubbling with CO2 in the presence of water, the yellow rhodium complexes move into the water phase, whereas bubbling with N2 at 60 °C causes them to switch back into the organic phase. The catalysts can be used for reactions in water or an organic phase.
- Desset, Simon L.,Cole-Hamilton, David J.
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supporting information; experimental part
p. 1472 - 1474
(2009/07/25)
-
- Discovery of 2,4,6-trisubstituted N-arylsulfonyl piperidines as γ-secretase inhibitors
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Development of cis-2,4,6-trisubstituted piperidine N-arylsulfonamides as γ-secretase inhibitors for the potential treatment of Alzheimer's disease (AD) is reported.
- Li, Hongmei,Asberom, Theodros,Bara, Thomas A.,Clader, John W.,Greenlee, William J.,Josien, Hubert B.,McBriar, Mark D.,Nomeir, Amin,Pissarnitski, Dmitri A.,Rajagopalan, Murali,Xu, Ruo,Zhao, Zhiqiang,Song, Lixin,Zhang, Lili
-
p. 6290 - 6294
(2008/09/17)
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- Nickel-catalyzed multi-component connection reaction of isoprene, aldimines (lactamines), and diphenylzinc
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Ni(acac)2 catalyzes the four-component connection reaction of diphenylzinc, isoprene, aromatic aldehydes, and aromatic amines in this order and provides stereochemically homogeneous (E)-1-arylamino-1-aryl-3-methyl-5-phenyl-3-pentenes (1) in excellent yields. Aliphatic aldehydes react similarly and give (E)-1-arylamino-1-alkyl-3-methyl-5-phenyl-3-pentenes (1) in slightly reduced yields. When the alkyl groups are bulky, in addition to 1 are formed (E)-1-arylamino-1-alkyl-4-methyl-5-phenyl-3-pentenes (1′) as the minor products. Lactamines prepared in situ from five- and six-membered lactols and aromatic amines are more reactive than alkyl aldehyde aldimines and furnish (E)-4-arylamino-6-methyl-8-phenyl-6-octen-1-ols (4) and (E)-5-arylamino-7-methyl-9- phenyl-7-nonen-1-ols (5), respectively, in good yields with excellent E-stereoselectivity.
- Kojima, Keisuke,Kimura, Masanari,Ueda, Satoshi,Tamaru, Yoshinao
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p. 7512 - 7520
(2007/10/03)
-
- Direct coupling reaction between alcohols and silyl compounds: Enhancement of Lewis acidity of Me3SiBr using InCl3
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The combination of InCl3 and Me3SiBr provided an enhanced Lewis acid system that can be used to promote a wide range of direct coupling reactions between alcohols and silyl nucleophiles in non-halogenated solvents, such as hexane or MeCN. The enhanced Lewis acidity of this system was measured by the 13C NMR in terms of the coordination to an alcohol. Moreover, the interaction between Me3SiBr and the In(III) species was revealed by 29Si NMR spectral analysis. Highly chemoselective allylations toward a hydroxyl moiety over ketone and acetoxy ones have been demonstrated.
- Saito, Takahiro,Nishimoto, Yoshihiro,Yasuda, Makoto,Baba, Akio
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p. 8516 - 8522
(2007/10/03)
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- Method of treating dry eye disorders using 13(S)-HODE and its analogs
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The topical use of 13(S)-HODE and analogs are disclosed for the treatment of dry eye disorders.
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Page/Page column 5; 6
(2010/11/08)
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- Oxidation of ethers with dimethyldioxirane
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Oxidation of a series of tert-butyl ethers ButOR (R = Me, Et, CH2CH2Cl, Pri, Bui), diethyl ether, diisopropyl ether, 1,2-dimethoxyethane, diisobutoxymethane, 1,4-dioxane, and tetrahydrofuran with dimethyldioxirane (DMDO) was studied. The reaction kinetics obeys the second-order equation w = k[DMDO][ether]. The rate constants in a range of 5-50°C and the activation parameters of the reaction were determined. The solvent effect on the oxidation rate was studied. The oxidation products are the corresponding alcohols and carbonyl compounds. The competition between the nonradical (oxygen insertion) and radical mechanisms of the reaction is discussed. The reactions of the parent dioxirane and DMDO with a series of methyl ethers MeOR′ (R′ = Me, Et, CH2CH2F, Pri) were studied by the density functional theory (DFT). The (U)B3LYP-6-311G(d,p) method was employed to calculate the geometry and energies of the reactants and transition states. The data obtained indicate a possible increase in the probability of oxidation via the radical route and an increase in the activation barrier for the substrates containing electron-withdrawing substituents.
- Grabovskiy,Timerghazin,Kabal'nova
-
p. 2384 - 2393
(2007/10/03)
-
- PROCESS FOR THE HYDROFORMYLATION OF ETHYLENICALLY UNSATURATED COMPOUNDS
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The present invention provides a process for the hydroformylation of ethylenically unsaturated compounds, which process comprises reacting said ethylenically unsaturated compound with carbon monoxide and hydrogen, in the presence of a catalyst system and a solvent, the catalyst system obtainable by combining: a) a metal of Group VIII or a compound thereof; and b) a bidentate phosphine, the process characterised in that a chlorine moiety is present in at least one of the said Group VIII metal compound or said solvent.
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