- Unmatched efficiency and selectivity in the epoxidation of olefins with oxo-diperoxomolybdenum(VI) complexes as catalysts and hydrogen peroxide as terminal oxidant
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A great variety of olefinic substrates having aromatic, carbocyclic and aliphatic olefins are effectively and selectively oxidized with oxygen-rich molybdenum(VI) complexes, namely [MoO(O2)2·2QOH] 1, [MoO(O2)(QO)2] 2, [Mo(O)2(QO)2] 3, [PPh4][MoO(O2)2(QO)] 4, [PPh4][Mo(O)2(O2)(QO)] 5 and [PPh4][Mo(O)3(QO)] 6 (QOH = 8-quinolinol) as catalyst, NaHCO3 as co-catalyst and H2O2 as the terminal oxidant, at room temperature. Catalysts 1 and 4 show unmatched yield, turnover number (TON) and turnover frequency (TOF), and hence shortest reaction time.
- Maiti, Swarup K.,Dinda, Subhajit,Bhattacharyya, Ramgopal
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- Effect of carbon dioxide addition on the phase behavior of epoxidation reaction mixtures in ionic liquids
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Volatile organic compounds can be replaced by more benign alternatives, such as ionic liquids (ILs) and supercritical carbon dioxide (scCO2). Previously, we showed that ILs offer advantages as solvents for epoxidation reactions (Kazemi et al. G
- Kazemi, Somayeh,Peters, Cor J.,Kroon, Maaike C.
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- The dihydrofuran template approach to furofuran synthesis
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Flash vacuum pyrrolysis of vinyl epoxides provides cis-dihydrofuran carboxylic esters in good yields and diastereoselectivities, which, on base-promoted epimerisation afford the complementary trans series. The compounds provide a viable template for a Lewis acid promoted cyclisation to provide the 2,6-diaryl-3,7-dioxabicyclo[3.3.0]octane core found in the furofuran series of natural lignans. This strategy is stereodivergent and can be controlled to provide the exo-exo, exo-endo or endo-endo stereochemistries. The approach has been exemplified in syntheses of the sesamyl furofurans (±)-epiasarinin and (±)-asarinin. The Royal Society of Chemistry 2006.
- Aldous, David J.,Batsanov, Andrei S.,Yufit, Dmitrii S.,Dalenon, Anne J.,Dutton, William M.,Steel, Patrick G.
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- Tuning the oxidation properties of vanadium(V) through ligand stoichiometry
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Vanadium(V) (5 mol %) and hydroxamic acid ligand (45 mol %) were found to promote the selective tert-butyl hydroperoxide-mediated oxidation of allylic and propargylic alcohols to the corresponding aldehydes and ketones.
- Zeng, Wei,Ballard, T. Eric,Melander, Christian
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- Highly enantioselective and efficient asymmetric epoxidation catalysts: Inorganic nanosheets modified with α-amino acids as ligands
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Layered catalyst: The attachment of α-amino acid ligands to inorganic nanosheets for use as ligands to vanadium, resulted in a catalyst that enhanced the enantioselectivity of the epoxidation of allylic alcohols (see picture). The catalyst can be colloidized, allowing for the catalytic reactions to be carried out under pseudo-homogeneous reaction conditions and also the catalysts to be directly recycled by simple liquid/liquid separation. Copyright
- Wang, Jiuzhao,Zhao, Liwei,Shi, Huimin,He, Jing
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- Manganese-catalyzed epoxidations of alkenes in bicarbonate solutions
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This paper describes a method, discovered and refined by parallel screening, for the epoxidation of alkenes. It uses hydrogen peroxide as the terminal oxidant, is promoted by catalytic amounts (1.0-0.1 mol %) of manganese(2+) salts, and must be performed using at least catalytic amounts of bicarbonate buffer. Peroxymonocarbonate, HCO4-, forms in the reaction, but without manganese, minimal epoxidation activity is observed in the solvents used for this research, that is, DMF and tBUOH. More than 30 d-block and f-block transition metal salts were screened for epoxidation activity under similar conditions, but the best catalyst found was MnSO4. EPR studies show that Mn2+ is initially consumed in the catalytic reaction but is regenerated toward the end of the process when presumably the hydrogen peroxide is spent. A variety of aryl-substituted, cyclic, and trialkyl-substituted alkenes were epoxidized under these conditions using 10 equiv of hydrogen peroxide, but monoalkyl-alkenes were not. To improve the substrate scope, and to increase the efficiency of hydrogen peroxide consumption, 68 diverse compounds were screened to find additives that would enhance the rate of the epoxidation reaction relative to a competing disproportionation of hydrogen peroxide. Successful additives were 6 mol % sodium acetate in the tBUOH system and 4 mol % salicylic acid in the DMF system. These additives enhanced the rate of the desired epoxidation reaction by 2-3 times. Reactions performed in the presence of these additives require less hydrogen peroxide and shorter reaction times, and they enhance the yields obtained from less reactive alkene substrates. Possible mechanisms for the reaction are discussed.
- Lane, Benjamin S.,Vogt, Matthew,DeRose, Victoria J.,Burgess, Kevin
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- Co(thd)2: A superior catalyst for aerobic epoxidation and hydroperoxysilylation of unactivated alkenes: Application to the synthesis of spiro-1,2,4-trioxanes
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Bis(2,2,6,6-tetramethyl-3,5-heptanedionato)cobalt(II) (Co(thd) 2), a β-diketonate prepared in a simple one-step procedure, is an excellent catalyst for aerobic epoxidation and Mukaiyama-Isayama hydroperoxysilylation of unactivated alkenes. For hydroperoxysilylation, Co(thd)2 is superior to Co(acac)2 and can catalyse oxidation of cyclic alkenes in excellent yield. Chiral β-diketonate or keto iminato catalysts failed to catalyse this reaction in an enantioselective manner and a free radical mechanism consistent with this observation is proposed. Hydroperoxysilylation of cyclohex-1-enylmethanol by Co(thd) 2 followed by addition of a ketone/TsOH provides a simple one-pot procedure for the synthesis of spiro-1,2,4-trioxane antimalarials.
- O'Neill, Paul M.,Hindley, Stephen,Pugh, Matthew D.,Davies, Jill,Bray, Patrick G.,Park, B. Kevin,Kapu, Dauda S.,Ward, Stephen A.,Stocks, Paul A.
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- Synthesis of titanium alkoxide complexes with alkyl lactate ligands. Asymmetric epoxidation of cinnamyl alcohol
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A family of titanium (IV) alkoxide compounds [{Ti(OPri) 3(OLact)}2], and [Ti(OPri)2(OLact) 2] (1-6) have been prepared by alcohol exchange of Ti(OPr i)4 and the corresponding alkyl-2-hydroxy-alkylpropionate or alkyl lactate (LactOH = Benzyl-(S)-lactate, methyl-(S)-3-phenyllactate and menthyl-(S)-lactate. These alkoxide titanium (IV) compounds have been characterized by spectroscopic and electrochemical techniques. In addition, these chiral Lewis acid titanium compounds have been studied in the asymmetric epoxidation of cynnamyl alcohol, the obtained results show that these complexes with dynamic behaviour in solution exert low control of the enantioselectivity. Electronic and sterical effects of the ligands in the catalytic results have been studied.
- Pérez, Yolanda,Del Hierro, Isabel,Fajardo, Mariano
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- Enantio- and stereo-selective route to the taxol side chain via asymmetric epoxidation of trans-cinnamyl alcohol and subsequent epoxide ring opening
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The first route to the side chain of Taxol and Taxotere, employing asymmetric epoxidation (AE) of trans-cinnamyl alcohol and a new highly regio- and stereo-selective opening of the epoxide ring with MgBr2, is described.
- Bonini,Righi
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- Design of a highly efficient catalyst for the oxaziridinium-mediated epoxidation of olefins by Oxone
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2,3,3-Trimethyl-7-nitro-3,4-dihydroisoquinolinium tetrafluoroborate is a highly efficient catalyst for the oxaziridinium-mediated epoxidation of a variety of olefins, including monosubstituted ones.
- Bohé, Luis,Kammoun, Majed
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- 2,2,2-Trifluoroacetophenone: An organocatalyst for an environmentally friendly epoxidation of alkenes
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A cheap, mild, fast, and environmentally friendly oxidation of olefins to the corresponding epoxides is reported using polyfluoroalkyl ketones as efficient organocatalysts. Namely, 2,2,2-trifluoroacetophenone was identified as an improved organocatalyst for the epoxidation of alkenes. Various olefins, mono-, di-, and trisubstituted, are epoxidized chemoselectively in high to quantitative yields utilizing 2-5 mol % catalyst loading and H2O 2 as the green oxidant.
- Limnios, Dimitris,Kokotos, Christoforos G.
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- First highly enantioselective epoxidation of alkenes with aldehyde/Oxone
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Optically active aldehydes have been successfully used as catalysts for asymmetric epoxidations of unfunctionalized alkenes (ee up to 94%) by using Oxone as the oxygen source. Experimental results indicate that the in-situ-generated aldehyde dioxirane is responsible for this catalytic activity.
- Bez, Ghanashyam,Zhao, Cong-Gui
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- Efficient biocatalysis for the production of enantiopure (S)-epoxides using a styrene monooxygenase (SMO) and Leifsonia alcohol dehydrogenase (LSADH) system
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Herein we report the production of enantiopure epoxides through biocatalysis using recombinant Escherichia coli cells expressing Rhodococcus sp. ST-10 styrene monooxygenase (SMO) and Leifsonia sp. S749 alcohol dehydrogenase (LSADH) genes are described. Rhodococcus sp. ST-10 SMO catalyzed the epoxidation of various alkenes, including styrene derivatives, vinyl pyridines, and linear alkenes, to give (S)-epoxides. NADH was regenerated by the reduction of NAD + by LSADH with 2-propanol. The E. coli biocatalyst was used in an aqueous/organic biphasic reaction system and the reaction conditions were optimized. Under the optimized conditions, 170 mM of (S)-styrene oxide was obtained from styrene in the organic phase with excellent enantiomeric excess (99.8%). This biocatalytic process was used to synthesize various (S)-epoxides.
- Toda, Hiroshi,Imae, Ryouta,Itoh, Nobuya
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- A study of V-pillared layered double hydroxides as catalysts for the epoxidation of terpenic unsaturated alcohols
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Mg,Al-Layered double hydroxides (LDHs) are pillared with vanadium under mildly acidic conditions. Via XRD, Raman, and IR characterization, it is confirmed that the material is a phase-pure LDH with decavanadate (V10O286-) anions between the brucite sheets. This V10-LDH has the highest activity for the epoxidation of geraniol when used with tert-butyl hydroperoxide as the oxidant in anhydrous toluene. In a series of tests, the possible release of catalytically active dissolved V from the catalyst is investigated. Under all conditions tested, V10-LDH behaves as a heterogeneous catalyst, in contrast with some other tested V-containing materials (e.g., VAPO-5, or V in a siliceous matrix). Regioselectivity in the epoxidation of geraniol evidences the coordination of the alcohol group of geraniol on the active V center. Finally, it is demonstrated that the V10-LDH catalyst can be applied to the epoxidation of a series of allylic and homoallylic alcohols, mostly of terpene origin.
- Villa, Aida L.,De Vos, Dirk E.,Verpoort, Francis,Sels, Bert F.,Jacobs, Pierre A.
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- Catalytic oxaziridinium-mediated epoxidation of olefins by Oxone. A convenient catalyst excluding common side reactions
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The nicely crystalline, easily prepared and handled, 3,3-dimethyl-3,4-dihydroisoquinolinium salt 6, is a convenient catalyst for the oxaziridinium-mediated epoxidation of alkenes by Oxone.
- Bohé, Luis,Kammoun, Majed
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- A new and efficient catalytic isomerization of cis- and trans-epoxides
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We report new ruthenium-catalyzed cis-trans isomerization of various functionalized epoxides. Enantiospecific isomerization of chiral epoxides is achieved without loss of enantiopurity, and epimerization occurs only at the epoxide carbon of the activating group.
- Lo, Ching-Yu,Pal, Sitaram,Odedra, Arjan,Liu, Rai-Shung
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- Cyclohexanones derived from dihydrocarvone as precursor of chiral dioxiranes for epoxidation of olefins
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New ketones having an axial α-fluorine atom and substituents other than fluorine at C8, derived from commercially available (+)-dihydrocarvone, have been prepared and used for epoxidations of trans stilbene, trans methyl p-methoxy cinnamate, trans cinnamyl alcohol and derivatives. It was found that replacement of the H at C8 by a substituent containing an oxygen atom increases the enantioselectivities in all cases. It was also shown that protic substituents (hydroxyl groups) provide a decrease in enantioselectivity in the case of cinnamates probably because of H-bonding dioxirane-substrate. It is noted that the absolute configurations of the various epoxides obtained hold with the usual model involving a spiro-approach on the dioxirane conformation C1 having the α-fluorine axial. Moreover, sub-stoichiometric amounts (0.3 equiv) of ketone can be used in all cases as these ketones do not undergo Baeyer-Villiger oxidation and are recovered. Graphical abstract.
- Solladié-Cavallo, Arlette,Jierry, Lo?c,Lupattelli, Paolo,Bovicelli, Paolo,Antonioletti, Roberto
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- Development of a new triphase catalyst and its application to the epoxidation of allylic alcohols
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(formula presented) A new triphase catalyst has been developed. When an aqueous solution of H3PW12O40 (1) was added to a solution of the amphiphilic chain copolymer 2, a new self-assembled and macroporous complex 3 was formed. This complex was effective as a catalyst in the epoxidation of allylic alcohols. Even in the use of 2.7 × 10-5 mole equiv of the catalyst, the epoxidation with aqueous H2O2 proceeded without organic solvents to give the corresponding epoxy alcohols in high yields.
- Yamada, Yoichi M. A.,Ichinohe, Masato,Takahashi, Hideyo,Ikegami, Shiro
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- The diastereoselective epoxidation of olefins in supercritical carbon dioxide
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Allylic alcohols are epoxidized with tert-butyl hydroperoxide in the presence of a vanadyl salen oxo-transfer catalyst in supercritical CO2. The metal catalyst was prepared in a simple two step, Schiff base reaction to form the salen ligand, followed by complexation to the vanadyl group. The epoxidation reactions are clean and give both high yields and good diastereoselectivity.
- Haas, Geoffrey R.,Kolis, Joseph W.
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- Identifying catalytically active mononuclear peroxoniobate anion of ionic liquids in the epoxidation of olefins
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The organic carboxylic acid coordinated monomeric peroxoniobate-based ionic liquids (ILs) [TBA][NbO(OH)2(R)] (TBA = tetrabutylammonium; R = lactic acid (LA), glycolic acid (GLY), malic acid (MA)) were prepared and fully characterized by elemental analysis, NMR, IR, Raman, TGA, 93Nb NMR, and HRMS. These IL catalysts exhibited not only high catalytic activity for the epoxidation of olefins under very mild reaction conditions, as the turnover frequency of [TBA][NbO(OH)2(LA)] reached up to 110 h-1, but also satisfactory recyclability in the epoxidation by using only 1 equiv of hydrogen peroxide as an oxidant. Meanwhile, this work revealed that the ILs underwent structural transformation from [NbO(OH)2(R)]- to [Nb(O-O)2(R)]- (R = LA, GLY, MA) in the presence of H2O2 by a subsequent activity evaluation, characterization, and first-principles calculations. Moreover, the organic carboxylic acid coordinated monomeric peroxoniobate-based ILs were investigated using density functional theory (DFT) calculations, which identified that [Nb(O-O)2LA]- was more advantageous than [Nb(O-O)2(OOH)2]- for the epoxidation of olefins. Due to the coordination between the α-hydroxy acids and the monomeric peroxoniobate anions, the functionalized ILs can efficiently catalyze the epoxidation of a wide range of olefins and allylic alcohols under very mild conditions. Additionally, the effect of solvents on the reaction is illustrated. It was found that methanol can lower the epoxidation barriers by forming a hydrogen bond with a peroxo ligand attached to the niobium center.
- Ma, Wenbao,Yuan, Haiyang,Wang, Haifeng,Zhou, Qingqing,Kong, Kang,Li, Difan,Yao, Yefeng,Hou, Zhenshan
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- Efficient and selective oxidation of alcohols to carbonyl compounds at room temperature by a ruthenium complex catalyst and hydrogen peroxide
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In this study, convenient and selective oxidation of alcohols using aqueous hydrogen peroxide to yield carbonyl compounds was studied. Using the ruthenium-(4-methylphenyl-2,6-bispydinyl) pyridinedicarboxylate complex [Ru(mpbp)(pydic)] as a catalyst, primary and secondary alcohols were oxidized to aldehydes and ketones at room temperature with a satisfactory yield and excellent selectivity. The influence of various reaction parameters, such as solvent, catalyst and oxidant amount on both the activity and selectivity was also evaluated. Kinetic studies showed that the oxidation of alcohol was first order in terms of the substrate and hydrogen peroxide, and was second order in terms of the catalyst. A plausible mechanism involving ruthenium-oxo species with electrophilic character was proposed based on the in situ UV-vis spectroscopy studies and Hammett plots.
- Wang, Jie-Xiang,Zhou, Xian-Tai,Han, Qi,Guo, Xiao-Xuan,Liu, Xiao-Hui,Xue, Can,Ji, Hong-Bing
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- Scalable, stereoselective syntheses of α,β-difluoro-γ-amino acids
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Backbone-fluorinated gamma-amino acids are novel shape-controlled building blocks that have potential utility in a variety of biological contexts. However, their synthesis poses challenges in terms of chemo-, regio- and stereoselectivity, and this has proven to be the major bottleneck in the ongoing development of their various biological applications. To address this problem, several new synthetic strategies were investigated in this work. This has led to the identification of new methods that are superior in terms of yield and stereocontrol.
- Patel, Alpesh Ramanlal,Hu, Xiang-Guo,Lawer, Aggie,Ahmed, Md. Iqbal,Au, Catherine,Jwad, Rasha,Trinh, Johny,Gonzalez, Christina,Hannah, Elizabeth,Bhadbhade, Mohan M.,Hunter, Luke
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- Synthesis and catalytic epoxidation potential of oxodiperoxo molybdenum(VI) complexes with 2-hydroxybenzohydroxamate and 2-hydroxybenzoate: The crystal structure of PPh4[MoO(O2)2(HBA)]
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(PPh4)2[MoO(O2)2(SHAH)] ·H2O and PPh4[MoO-(O2)2(HBA)] (SHAH3 = 2-hydroxybenzohydroxamic acid and HBAH = 2-hydroxybenzoic acid) have been synthesized and characterized by physico-chemical and spectroscopic methods. In addition, the second complex has been structurally characterized by single-crystal X-ray diffraction analysis. We have compared the catalytic activities of these two new complexes, together with the previously reported PPh4[MoO(O2)2(BZ)] (BZH = benzoic acid), with respect to the epoxidation of alkenes. The hydroxamate complex is the most efficient catalyst among the three complexes, showing excellent catalytic activity for the substrates cyclohexene, cyclooctene, cinnamyl alcohol, pent-4-en-1-ol and hex-1-ene. Springer Science+Business Media B.V. 2010.
- Gharah, Narottam,Chattopadhyay, Basab,Maiti, Swarup K.,Mukherjee, Monika
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- An improved methyltrioxorhenium-catalyzed epoxidation of alkenes with hydrogen peroxide
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Methyltrioxorhenium (MTO)-catalyzed epoxidation of alkenes with H 2O2 has been significantly improved by using 3-methylpyrazole as an additive. A system consisting of 35% H2O 2 and MTO-3-methylpyrazole in CH2Cl2 catalyzes the epoxidation of various alkenes in excellent yields. The catalytic activity of MTO-3-methylpyrazole surpasses MTO-pyrazole and MTO-pyridine catalysts. Quantitative yields of epoxides from cyclic and internal alkenes were obtained with only 0.05-0.1 mol% of MTO in the presence of 10 mol% of 3-methylpyrazole. The Royal Society of Chemistry.
- Yamazaki, Shigekazu
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- Oxazolidine sulfur ylides derived from phenylglycinol for the specific and highly diastereoselective synthesis of aryl and alkyl trans-epoxyamides
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Aryl and alkyl chiral oxazolidine sulfonium salts with cis and trans dispositions derived from (-)-(R)-2-phenylglycinol were demonstrated to be good to excellent chiral auxiliaries for the diastereoselective synthesis of (2R,3S)-trans-epoxyamides. Interes
- Gordillo, Paola G.,Aparicio, David M.,Flores, Marcos,Mendoza, Angel,Orea, Laura,Juarez, Jorge R.,Huelgas, Gabriela,Gnecco, Dino,Teran, Joel L.
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- Asymmetric Epoxidation of Allylic Alcohol by the Modified Sharpless Reagent
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The modified Sharpless reagent can be applied to the epoxidation of various allylic alcohols just as the Sharpless reagent does, but the reaction time was greatly reduced.Methyl gibberellate 10, which failed to give the normal epoxidation product on treatment with Sharpless reagent, readily yielded the corresponding epoxy derivative 22 when the modified Sharpless reagent was used.
- Wang, Zhi-Min,Zhou, Wei-Shan
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- Selective photocatalytic oxidation of alcohols to corresponding aldehydes in solvent-free conditions using porphyrin sensitizers
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Abstract: In this work, selective and aerobic photooxidation of a range of aromatic, aliphatic and α,β-unsaturated alcohols to corresponding carbonyl compounds has been performed with tetraphenylporphyrin (H2TPP), ClFeTPP and ZnTPP as sensitizers using visible light and in the presence of molecular oxygen in solvent-free conditions. The conversion rates for alcohols oxidations were in the order of free-base porphyrin (H2TPP)?>?metalloporphyrin (ClFeTPP) and (ZnTPP). This method has a wide range of applications, remarkable conversion and product yield in reasonable time, does not include cumbersome work-up, exhibits chemoselectivity, and proceeds under mild reaction conditions. As the matter of oxidation of cycloheptanol and cyclooctanol using H2TPP as photosensitizer, the TON reached up to 1686 and 2464, respectively and selectivity more than 99?%. Graphical abstract: [Figure not available: see fulltext.]
- Mehrabi-Kalajahi, Seyed Saeed,Hajimohammadi, Mahdi,Safari, Nasser
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- An efficient ketone-catalyzed asymmetric epoxidation using hydrogen peroxide (H2O2) as primary oxidant
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High enantioselectivities have been obtained for asymmetric epoxidation of olefins using a fructose-derived chiral ketone (5) as catalyst and hydrogen peroxide as primary oxidant.
- Shu, Lianhe,Shi, Yian
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- New chiral amino alcohol ligands for catalytic enantioselective addition of diethylzincs to aldehydes
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A study aimed at the synthesis and structure optimization of new, efficient, optically active β-amino alcohol ligands with a structure suitable for immobilization on magnetite nanoparticles has been carried out. The optimized homogeneous amino alcohol catalysts 13a and 13b, the chirality of which arises from the Sharpless epoxidation of suitable allyl alcohols, were tested by employing the well-established enantioselective amino alcohol-promoted addition of diethylzinc to benzaldehyde, giving the corresponding benzyl alcohol with nearly quantitative yield and ee = 95%. Then, their broad applicability as chiral catalysts was evaluated by carrying out the same reaction on a family of aldehydes, including variously substituted aromatic ones as well as an aliphatic analogue. The results have confirmed the validity of the fine-tuning process performed on ligands 13a and 13b. In fact, both exhibited excellent catalytic activity as demonstrated by the chemical yields and ee obtained from all the tested aldehydes, almost independent of the position and type of substitution in the aromatic ring.
- Sappino, Carla,Mari, Alessandra,Mantineo, Agnese,Moliterno, Mauro,Palagri, Matteo,Tatangelo, Chiara,Suber, Lorenza,Bovicelli, Paolo,Ricelli, Alessandra,Righi, Giuliana
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- Chromium Silicalite-2 (CrS-2): an Efficient Catalyst for the Chemoselective Epoxidation of Alkenes with TBHP
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Chromium-containing medium-pore molecular sieve (Si/Cr > 140) having MEL (CrS-2) topology efficiently catalyses the chemoselective epoxidation of various olefins to the corresponding epoxides using 70percent tert-butyl hydroperoxide (TBHP) as an oxidant.
- Joseph, Reni,Sasidharan, M.,Kumar, R.,Sudalai, A.,Ravindranathan, T.
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- Liquid-Phase Synthesis of Chiral Tartrate Ligand Library for Enantioselective Sharpless Epoxidation of Allylic Alcohols
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This paper reports a successful development of a group of efficient soluble polymer-supported chiral tartrate ligands by liquid-phase synthesis for Sharpless epoxidation of a variety of allylic alcohols through ligand diversity. The influence of substituent in chiral tartrate ligands on the enantioselectivities of the reaction was disclosed. Moderate chemical yields and good enantiomeric excesses were obtained by using soluble polymer-supported tartrate ester in the epoxidation of allylic alcohols with Ti(O-i-Pr) 4/tert-butyl hydroperoxide.
- Guo, Hong-Chao,Shi, Xue-Yan,Wang, Xian,Liu, Shang-Zhong,Wang, Min
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- An alternate synthesis of appetite suppressant (R)-2-benzylmorpholine employing Sharpless asymmetric epoxidation strategy
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An alternate synthesis of (R)-2-benzylmorpholine 1, an appetite suppressant agent has been accomplished starting from readily available trans-cinnamyl alcohol employing Sharpless asymmetric epoxidation strategy as a key step, with an overall yield of 24%.
- Viswanadh,Mujumdar,Sasikumar,Kunte,Muthukrishnan
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- Niobium peroxide-catalyzed selective epoxidation of allylic alcohols
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Modified niobium peroxides were prepared and used for catalyzing the epoxidation of allylic alcohols with hydrogen peroxide in the absence of any other solvent under ice bath conditions. Niobium peroxides modified with ionic liquid-type 1-dodecyl- 3-methylimidazolium hydroxide or conventional tetradecyl trimethyl ammonium hydroxide surfactants demonstrated excellent yields (80-99%) for the epoxidation of allylic alcohols to their epoxides even if the reaction was performed without any other solvent at 0°C for 0.5 h. The catalyst characterization demonstrated that the surfactant molecules were anchored on the surface of the niobium catalyst by weak noncovalent interactions. Compared with niobium peroxides, the modified amphiphilic catalysts allowed easier accessibility to hydrophobic substrates and thus demonstrated high reaction rate and excellent recyclability for the epoxidation under mild conditions.
- Chen, Chen,Zhao, Xiuge,Chen, Jizhong,Hua, Li,Zhang, Ran,Guo, Li,Song, Baoning,Gan, Huimei,Hou, Zhenshan
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- A chemoenzymic approach to the epoxidation of alkenes in aqueous media
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Hydrogen peroxide, generated insitu by the enzymic oxidation of glucose using glucose oxidase, is coupled to a catalytic system of sodium bicarbonate/manganese sulfate to epoxidize alkenes in aqueous media.
- Tong, Kit-Ho,Wong, Kwok-Yin,Chan, Tak Hang
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- Enantioselective epoxidation of alkenes catalyzed by 2-fluoro-N-carbethoxytropinone and related tropinone derivatives
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Several α-substituted N-carbethoxytropinones have been evaluated as catalysts for asymmetric epoxidation of alkenes with Oxone, via a dioxirane intermediate. α-Fluoro-N-carbethoxytropinone (2) has been studied in detail and is an efficient catalyst which does not suffer from Baeyer-Villiger decomposition and can be used in relatively low loadings. This ketone was prepared in enantiomerically pure form using chiral base desymmetrization of N-carbethoxytropinone. Asymmetric epoxidation catalyzed by 2 affords epoxides with up to 83% ee. Among other derivatives tested, the α-acetoxy derivative 7 affords the highest enantioselectivities.
- Armstrong, Alan,Ahmed, Ghafoor,Dominguez-Fernandez, Belen,Hayter, Barry R.,Wailest, J. Steven
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- Intermolecular Amine Transfer to Enantioenriched trans-3Phenylglycidates by an α/β-Aminomutase to Access Both anti-Phenylserine Isomers
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β-Hydroxy-α-amino acids are noncanonical amino acids with two stereocenters and with useful applications in the pharmaceutical and agrochemical sectors. Here, a 5-methylidene-3,5-dihydro-4H-imidazol-4-one-dependent aminomutase from Taxus canadensis (TcPAM) was repurposed to transfer the amino group irreversibly from (2S)-styryl-α-alanine to exogenously supplied trans-3-phenylglycidate enantiomers, producing anti-phenylserines stereoselectively. TcPAM catalysis inverted the intrinsic regioselective chemistry from amination at Cβ to Cα of enantioenriched trans-3-phenylglycidates to make phenylserine predominantly (97%)phenylisoserine (～3% relative abundance). Gas chromatography?mass spectrometry analysis of the chiral auxiliary derivatives of the biocatalyzed products confirmed that the amine transfer was stereoselective for each glycidate enantiomer. TcPAM converted (2S,3R)-3-phenylglycidate to (2S)-anti-phenylserine predominantly (89%) and (2R,3S)-3-phenylglycidate to (2R)-anti-phenylserine (88%)their antipodes, with inversion of the configuration at Cα in each case. Both glycidate enantiomers formed a small amount (～10%) of syn-phenylserine by retaining the configuration at Cα. The minor syn-isomer likely came from a β-hydroxy oxiranone intermediate formed by intramolecular ring opening of the oxirane ring by the carboxylate before amine transfer. TcPAM had a slight preference toward (2S,3R)-3-phenylglycidate, which was turned(kcat = 0.3 min?1) 1.5 times faster than the (2R,3S)-glycidate (kcat = 0.2 min?1). The catalytic efficiencies (kcatapp/KMapp ≈ 20 M?1s?1) of TcPAM for the antipodes were similar. The kinetic data supported a two-substrate ping-pong mechanism for the amination of the phenylglycidates, with competitive inhibition at higher glycidate substrate concentrations.
- Shee, Prakash K.,Yan, Honggao,Walker, Kevin D.
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- Borylation and rearrangement of alkynyloxiranes: A stereospecific route to substituted α-enynes
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1,3-Enynes are important building blocks in organic synthesis and also constitute the key motif in various bioactive natural products and functional materials. However, synthetic approaches to stereodefined substituted 1,3-enynes remain a challenge, as they are limited to Wittig and cross-coupling reactions. Herein, stereodefined 1,3-enynes, including tetrasubstituted ones, were straightforwardly synthesized from cis or trans-alkynylated oxiranes in good to excellent yields by a one-pot cascade process. The procedure relies on oxirane deprotonation, borylation and a stereospecific rearrangement of the so-formed alkynyloxiranyl borates. This stereospecific process overall transfers the cis or trans-stereochemistry of the starting alkynyloxiranes to the resulting 1,3-enynes.
- Fuentespina, Ruben Pomar,De La Cruz, José Angel Garcia,Durin, Gabriel,Mamane, Victor,Weibel, Jean-Marc,Pale, Patrick
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- Asymmetric epoxidation using hydrogen peroxide (H2O2) as primary oxidant
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High enantioselectivities have been obtained for asymmetric epoxidation of olefins using a fructose-derived chiral ketone as catalyst and hydrogen peroxide as primary oxidant.
- Shu, Lianhe,Shi, Yian
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- Practical and environmentally friendly epoxidation of olefins using Oxone
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A practical and efficient epoxidation of aromatic olefins using Oxone in a two-phase system (ethyl acetate - water) is described. The reported method is suitable for large-scale synthesis and does not require phase transfer catalyst (PTC) or pH control.
- Hashimoto, Norio,Kanda, Atsushi
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- 5-Chloro-7-iodo-8-quinolinolatomanganese(III) with the feature of pH-regulated molecular switches as a highly efficient catalyst for epoxidation of olefins with hydrogen peroxide
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A simple 5-chloro-7-iodo-8-quinolinolato-manganese(III) complex with the feature of pH-regulated molecular switches was conveniently synthesized and found to be a novel and highly efficient catalyst for the epoxidation of olefins with aqueous hydrogen peroxide in water-acetone media containing ammonium acetate and acetic acid as additives. This should be due to its special hexadentate binding structure that could be easily converted to the corresponding pentadentate form with a pendanthy droxy group via the opening of an axial Mn-O bond in the reaction media, as supported by in situ cyclic voltammetry and UV-vis spectra characterization.
- Zhong, Sheng,Fu, Zaihui,Tan, Yueming,Xie, Qingji,Xie, Fang,Zhou, Xiaoping,Ye, Zhengpei,Peng, Guosheng,Yin, Dulin
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- A simple, iron-catalyzed, pyridine-assisted hydrogen peroxide epoxidation system
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A simple and inexpensive system comprised of H2O 2-pyridine-FeCl3 · 6H2O for the catalysis of olefin epoxidation was established. Intriguingly, the reactivity of this system greatly depends on the amounts of pyridine. Various substrates, including aromatic and aliphatic olefins, were epoxidized by this simple system in moderate to excellent yields.
- Jiao, Mingyu,Matsunaga, Hirofumi,Ishizuka, Tadao
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- Peroxometalates immobilized on magnetically recoverable catalysts for epoxidation
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Magnetically separable catalysts were prepared and employed for the epoxidation of olefins with hydrogen peroxide. In all cases the magnetic core was firstly covered with a silica layer to prevent iron ion-initiated decomposition of hydrogen peroxide. The catalytic active species, an ionic liquid-type peroxotungstate, was then immobilized either by hydrogen bonding (catalyst 1) or by covalent SiO linkage (catalyst 2). In addition to a thorough characterization by FT-IR, XRD, NMR, DRIFT, XPS, and TEM, the catalytic potential was evaluated in the epoxidation of a variety of olefins as well as allylic alcohols. Both catalysts showed essentially a constant activity after at least ten consecutive cycles. On the basis of the research above, a new type of magnetically separable catalyst was constructed by immobilization of lacunary-type phosphotungstate by hydrogen bonding between the sulfonate anion and silanol group on the surface of the core-shell magnetic nanoparticles. After the detailed characterization, the catalyst was used in the epoxidation of a variety of olefins and allylic alcohols and was found to possess high activity, selectivity towards epoxides, and a constant activity after at least ten catalytic recycles without solvent.
- Qiao, Yunxiang,Li, Huan,Hua, Li,Orzechowski, Lars,Yan, Kai,Feng, Bo,Pan, Zhenyan,Theyssen, Nils,Leitner, Walter,Hou, Zhenshan
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- An Improved Asymmetric Epoxidation of Allyl Alcohols using Titanium-pillared Montmorillonite as a Heterogeneous Catalyst
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A simple and convenient procedure for the catalytic asymmetric epoxidation of primary allyl alcohols with high enantiomeric purities and good yields using a heterogeneous titanium-pillared montmorillonite catalyst is demonstrated.
- Choudary, B. M.,Valli, V. L. K.,Prasad, A. Durga
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- Selective oxidations of allylic alcohols using vanadyl and cobalt(II) alkyl phosphonate modified silicas
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A range of allylic alcohols can be selectively oxidised to either the corresponding epoxide or the enone in good yields using catalytic quantities of vanadyl or cobalt(II) alkyl phosphonate modified silicas, CoEPS3 and VOEPS3 and tert-butyl hydroperoxide.
- Jurado-Gonzalez, Magdalena,Sullivan, Alice C.,Wilson, John R.H.
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- Highly facile homogeneous epoxidation of olefins using oxo-diperoxo tungstate(VI) complex as catalyst, bicarbonate as co-catalyst and hydrogen peroxide as a terminal oxidant
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Addition of a dilute acetic acid solution of 8-quinolinol to an H 2O2 solution of freshly precipitated H2WO 4·2H2O furnishes a yellow adduct [WO(O 2)2·2QOH] 1 which, on crystallization from a suitable solvent, affords orange-yellow complex [WO(O2)(QO) 2] 2. When 2 reacts stoichiometrically with olefinic compounds in a 1:1 molar ratio, the respective olefins are epoxidized and 2 is converted to the orange-red [WO2(QO)2] 3. When 1 is treated with an excess of H2O2 (greater than 6 equiv.) and PPh4Cl, an anionic light yellow complex PPh4[WO(O2)2(QO)] 4 is obtained. 4 reacts with cyclopentene (a representative olefin) in a 1:1 molar ratio producing cyclopentene oxide and itself is converted to PPh 4[WO2(O2)(QO)] 5. If the above reaction is conducted at a 1:2 molar ratio (instead of 1:1) then 2 moles of the corresponding epoxide is formed and 4 is converted to PPh4[WO 3(QO)] 6. All these peroxo complexes have remarkable catalytic efficiencies in the epoxidation of olefinic compounds when used in tandem with NaHCO3 as co-catalyst and H2O2 as oxidant in a CH3CN medium at room temperature, the method being green and economical. The catalyst 4 under the above experimental conditions shows so far unmatched efficiency in epoxidizing a wide variety of olefinic substrates. the Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2006.
- Maiti, Swarup K.,Dinda, Subhajit,Gharah, Narottam,Bhattacharyya, Ramgopal
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- An Isolable and Bench-Stable Epoxidizing Reagent Based on Triazine: Triazox
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A new triazine-based oxidizing reagent, 2-hydroperoxy-4,6-diphenyl-1,3,5-triazine (Triazox), has been developed. The reagent can be synthesized from inexpensive starting materials and is a bench-stable solid that is isolable in pure form. Epoxidation of alkenes possessing acid-sensitive functionalities using Triazox proceeded in good to excellent yields. The accompanying nonacidic triazinone coproduct can be easily removed by filtration. These features indicate that Triazox is a practically useful oxidizing reagent.
- Yamada, Kohei,Igarashi, Yuki,Betsuyaku, Tatsuki,Kitamura, Masanori,Hirata, Koki,Hioki, Kazuhito,Kunishima, Munetaka
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- Three- and two-site heteropolyoxotungstate anions as catalysts for the epoxidation of allylic alcohols by H2O2 under biphasic conditions: Reactivity and kinetic studies of the [Ni3(OH2)3(B-PW9O34){WO5(H2O)}]7?, [Co3(OH2)6(A-PW9O34)2]12?, and [M4(OH2)2(B-PW9O34)2]10? anions, where M?=?Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)
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The trimetallic phosphopolyoxotungstate anions [Ni3(OH2)3(B-PW9O34){WO5(H2O)}]7? and [Co3(OH2)6(A-PW9O34)2]12? have been studied as epoxidation catalysts for oxygen transfer from 30% H2O2 to a range of allylic alcohols under biphasic conditions (1,2-dichloroethane/H2O) at 15 °C. The reaction mechanism involves coordination of an allylic alcohol at an M(II) site in each case, prior to transfer of a peroxy oxygen from an adjacent W(O2) site. The latter is formed from a terminal W = O unit by reaction with H2O2. Evidence of W(O2) formation was obtained through IR studies. The W(O2) group forms the epoxide by transfer of an oxygen atom to the C[dbnd]C bond of the coordinated allylic alcohol. Kinetic studies using 3-methyl-2-buten-1-ol as the allylic alcohol substrate have been modelled with all three metal sites catalytically active. The reaction involves an autocatalysis mechanism involving an induction period, which can be rationalised by proposing not only coordination of the allylic alcohol to M(II), but also the product hydroxy epoxide, both through their –OH groups. The autocatalysis is generated by formation of the W(O2) group adjacent to a coordinated hydroxy epoxide, which competes with coordination of allylic alcohol. The mechanism requires some twenty-one steps involving just the generic steps listed above, with all three metal sites catalytically active. Temperature-dependent kinetic studies and subsequent Eyring analyses have shown that the Co(II)-containing catalyst is the most active of the two. Analogous studies of the epoxidation of 3-methyl-2-buten-1-ol by the two-site [M4(OH2)2(B-PW9O34)2]10? ions as catalysts, where M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II), at 15 °C gave an order of reactivity of Cu(II) > Ni(II) > Zn(II), Co(II), Mn(II), which mostly mimics the natural order of stability constants (the Irving-Williams series), suggesting that the formation of the allylic alcohol complexes play a dominant role in this series of related complex anions, with greater replacement of water by allylic alcohol leading to greater reactivity.
- Abram, Paulus Hengky,Burns, Robert C.,Li, Lichun
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- First Total Synthesis of Jomthonic Acid A 1
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A stereoselective total synthesis of jomthonic acid A is described. The key features of the synthetic strategy are a Sharpless asymmetric epoxidation, a Gilmann reagent-induced methylation, a Mitsunobu reaction, a Yamaguchi esterification, and an O -(benzotriazol-1-yl)- N, N, N ′, N ′-tetramethyluronium tetrafluoroborate (TBTU)-mediated amide coupling. Jomthonic acid A is an architecturally rare amino acid containing a β-methylphenylalanine residue and a 4-methyl-(2 E,4 E)-hexa-2,4-dienoate moiety. It shows antidiabetic and antiatherogenic activities when tested against mouse ST-13 preadiopocytes.
- Dumpala, Mohan,Radha Krishna, Palakodety,Srinivas, Batthula
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supporting information
p. 69 - 72
(2019/12/30)
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- Synthesis and Structure-Activity Relationship Studies of C2-Modified Analogs of the Antimycobacterial Natural Product Pyridomycin
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A series of derivatives of the antimycobacterial natural product pyridomycin have been prepared with the C2 side chain attached to the macrocyclic core structure by a C-C single bond, in place of the synthetically more demanding enol ester double bond found in the natural product. Hydrophobic C2 substituents of sufficient size generally provide for potent anti-Mtb activity of these dihydropyridomycins (minimum inhibitory concentration (MIC) values around 2.5 μM), with several analogs thus approaching the activity of natural pyridomycin. Surprisingly, some of these compounds, in contrast to pyridomycin, are insensitive to overexpression of InhA in Mycobacterium tuberculosis (Mtb). This indicates that their anti-Mtb activity does not critically depend on the inhibition of InhA and that their overall mode of action may differ from that of the original natural product lead.
- Kienle, Maryline,Eisenring, Patrick,Stoessel, Barbara,Horlacher, Oliver P.,Hasler, Samuel,Van Colen, Gwéna?lle,Hartkoorn, Ruben C.,Vocat, Anthony,Cole, Stewart T.,Altmann, Karl-Heinz
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p. 1105 - 1131
(2020/03/10)
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- Enantiocomplementary Epoxidation Reactions Catalyzed by an Engineered Cofactor-Independent Non-natural Peroxygenase
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Peroxygenases are heme-dependent enzymes that use peroxide-borne oxygen to catalyze a wide range of oxyfunctionalization reactions. Herein, we report the engineering of an unusual cofactor-independent peroxygenase based on a promiscuous tautomerase that accepts different hydroperoxides (t-BuOOH and H2O2) to accomplish enantiocomplementary epoxidations of various α,β-unsaturated aldehydes (citral and substituted cinnamaldehydes), providing access to both enantiomers of the corresponding α,β-epoxy-aldehydes. High conversions (up to 98 %), high enantioselectivity (up to 98 % ee), and good product yields (50–80 %) were achieved. The reactions likely proceed via a reactive enzyme-bound iminium ion intermediate, allowing tweaking of the enzyme's activity and selectivity by protein engineering. Our results underscore the potential of catalytic promiscuity for the engineering of new cofactor-independent oxidative enzymes.
- Crotti, Michele,Kataja, Kim M.,Poelarends, Gerrit J.,Saravanan, Thangavelu,Xu, Guangcai
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p. 10374 - 10378
(2020/04/23)
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- Synthesis method of phenyl isoserine hydrochloride and intermediate thereof (by machine translation)
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The invention provides a method .for synthesizing phenyl isoserine hydrochloride and an intermediate thereof, II of the compound shown in formula, in the presence of a catalyst: and the method comprises the following steps, synthesizing paclitaxel and docetaxel in the following steps: synthesizing paclitaxel and docetaxel as shown in the following reaction I as shown, in the following steps: II, synthesizing paclitaxel and docetaxel in a low price . and synthesizing the paclitaxel and docetaxel in an inexpensive manner . The invention provides cheap chiral side chain raw material, for synthesizing paclitaxel and, docetaxel as shown in the following step: [,] The present invention provides cheap chiral side. chain raw materials. (by machine translation)
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Paragraph 0046-0049
(2020/04/02)
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- SO2F2-Mediated Epoxidation of Olefins with Hydrogen Peroxide
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An inexpensive, mild, and highly efficient epoxidation protocol has been developed involving bubbling SO2F2 gas into a solution of olefin, 30% aqueous hydrogen peroxide, and 4 N aqueous potassium carbonate in 1,4-dioxane at room temperature for 1 h with the formation of the corresponding epoxides in good to excellent yields. The novel SO2F2/H2O2/K2CO3 epoxidizing system is suitable to a variety of olefinic substrates including electron-rich and electron-deficient ones.
- Ai, Chengmei,Zhu, Fuyuan,Wang, Yanmei,Yan, Zhaohua,Lin, Sen
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p. 11928 - 11934
(2019/10/02)
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- Enantioselective Access to Chiral Cyclic Sulfamidates Through Iridium-Catalyzed Asymmetric Hydrogenation
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The Iridium-catalyzed asymmetric hydrogenation of cyclic sulfamidate imines was successfully developed with N-methylated ZhaoPhos L2 as the ligand. A variety of chiral cyclic sulfamidates were obtained with excellent results (up to 99% yield, 99% ee). Furthermore, this asymmetric hydrogenation can be employed as the key reaction step to prepare the important intermediates in organic synthesis. (Figure presented.).
- Liu, Yuanhua,Huang, Yi,Yi, Zhiyuan,Liu, Gongyi,Dong, Xiu-Qin,Zhang, Xumu
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supporting information
p. 1582 - 1586
(2019/02/19)
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- Recoverable polystyrene-supported catalysts for Sharpless allylic alcohols epoxidations
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In this work, new heterogeneous catalysts intended for enantioselective Sharpless epoxidation were prepared. The catalysts are based on Ti(IV) complexes of cross-linked swellable spherical copolymer beads of styrene with ethyl-(4-vinylbenzyl)-L-tartrate, or with ethyl-(2R,3R)-2,3-dihydroxy-4-oxo-5-(4-vinylphenyl)pentanoate. These catalysts were tested in epoxidation of cinnamyl alcohols. High conversion (up to 99%) and high enantioselectivity (up to 99% ee) were achieved in the case of catalysts based on copolymers of styrene with ethyl-(4-vinylbenzyl)-L-tartrate (5, 20, 50%). Unfortunately, the copolymers lost their enantioselectivity due to the leaching of L-tartrate, caused by alcoholysis of ester bond. This problem has been overcome by replacing the ester bond by a stable keto bond. The prepared catalyst based on the copolymer of styrene with ethyl-(2R,3R)-2,3-dihydroxy-4-oxo-5-(4-vinylphenyl)pentanoate (20%) achieved a similarly high conversion and enantioselectivity as in the previous case (up to 99%, up to 99% ee) and was successfully recycled.
- Bartá?ek, Jan,Drabina, Pavel,Váňa, Ji?í,Sedlák, Milo?
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p. 123 - 132
(2019/02/27)
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- Trialkylborane-Mediated Propargylation of Aldehydes Using γ-Stannylated Propargyl Acetates
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A transition-metal-free three-component process that combines aldehydes, 3-(tributylstannyl)propargyl acetates formed in situ from readily available propargyl acetates, and trialkylboranes provides access to a range of 1,2,4-trisubstituted homopropargylic alcohols. The addition of diisopropylamine plays a crucial role in the selective formation of homopropargylic alcohols. Importantly, this methodology can be extended to a single-flask reaction sequence starting from propargyl acetates.
- Horino, Yoshikazu,Murakami, Miki,Ishibashi, Mayo,Lee, Jun Hee,Watanabe, Airi,Matsumoto, Rio,Abe, Hitoshi
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supporting information
p. 9564 - 9568
(2019/12/24)
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- Towards Mechanistic Understanding of Liquid-Phase Cinnamyl Alcohol Oxidation with tert-Butyl Hydroperoxide over Noble-Metal-Free LaCo1–xFexO3 Perovskites
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Noble-metal-free perovskite oxides are promising and well-known catalysts for high-temperature gas-phase oxidation reactions, but their application in selective oxidation reactions in the liquid phase has rarely been studied. We report the liquid-phase oxidation of cinnamyl alcohol over spray-flame synthesized LaCo1–xFexO3 perovskite nanoparticles with tert-butyl hydroperoxide (TBHP) as the oxidizing agent under mild reaction conditions. The catalysts were characterized by XRD, BET, EDS and elemental analysis. LaCo0.8Fe0.2O3 showed the best catalytic properties indicating a synergistic effect between cobalt and iron. The catalysts were found to be stable against metal leaching as proven by hot filtration, and the observed slight deactivation is presumably due to segregation as determined by EDS. Kinetic studies revealed an apparent activation energy of 63.6 kJ mol?1. Combining kinetic findings with TBHP decomposition as well as control experiments revealed a complex reaction network.
- Waffel, Daniel,Alkan, Baris,Fu, Qi,Chen, Yen-Ting,Schmidt, Stefan,Schulz, Christof,Wiggers, Hartmut,Muhler, Martin,Peng, Baoxiang
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p. 1155 - 1163
(2019/09/06)
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- Catalytic oxidation of alcohols with novel non-heme N4-tetradentate manganese(ii) complexes
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We report the preparation and characterisation of a series of novel non-heme N4-tetradentate Mn(OTf)2 complexes of the type, [(L)MnOTf2], where L = R,R and S,S enantiomers of BPMCN, its 6-methyl and 6-bromo derivatives as well as the novel ligand BMIMCN (BPMCN = N,N′-dimethyl-N,N′-bis(2-pyridylmethyl)-(R,R/S,S)-1,2-diaminocyclohexane, BMIMCN = N,N′-dimethyl-N,N′-bis(1-methyl-2-imidazolemethyl)-(R,R/S,S)-1,2-diaminocyclohexane). Solid state structural analysis of the BMIMCN-ligated Mn-triflate complexes (R,R-C4 and S,S-C4) revealed opposite helicity but identical metal site accessibility. This feature was exploited in the catalytic oxidation of primary and secondary alcohols, with hydrogen peroxide as oxidant and acetic acid as co-catalyst. Complexes R,R-C4 and S,S-C4 displayed the highest activity in benzyl alcohol oxidation, attributed to the electron-donating property of the BMIMCN ligand. Complex S,S-C4, displayed high activity for a variety of primary alcohol substrates, but the reaction suffered from reduced selectivity and side-reactions due to the presence of acetic acid. In contrast, secondary alcohol substrates could be oxidised to the corresponding ketone products in excellent isolated yields under mild reaction conditions and short reaction times.
- Vermaak, Vincent,Young, Desmond A.,Swarts, Andrew J.
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supporting information
p. 16534 - 16542
(2018/12/05)
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- Oxygen bridged Homobinuclear Mn(II) compounds with Anthranilic acid: Theoretical calculations, oxidation and catalase activity
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Two new homobinuclear manganese compounds with mixed ligands, [Mn2(μ1,1–2-NH2C6H4COO)2(phen)4](ClO4)2(CH3OH) (1), and [Mn2(μ1,3–2-NH2C6H4COO)2(bipy)4](ClO4)2 (2) (NH2C6H4COOH?=?anthranilic acid, bipy?=?2,2′-bipyridine, phen?=?1,10- phenanthroline) were synthesized and thoroughly characterized by elemental analysis, IR, UV and single crystal X-ray crystallography. X-ray structure analysis shows that in the mono- and bidentate carboxylate bridged compounds, Mn–Mn distances of 1 and 2 are 3,461??, and 4,639??, respectively. The energy of the compounds was determined with a DFT (Density Functional Theory) calculation on B3LYP/6-31G(d,p) optimized geometry by using the B3LYP/6-31G(d,p) basis set. These compounds acts as biomimetic catalyst and show catalase-like activity for the hydrogen peroxide dismutation at room temperature in different solvents with remarkable activity (TOF, Turnover frequency?=?mol of subst./(mol of cat. × time)) up to 12640?h?1 with 1, and 17910?h?1 with 2 in Tris–HCl buffer). Moreover, the catalytic activity of 1 and 2 has been studied for oxidation of alcohols (cinnamyl alcohol, benzyl alcohol, cyclohexanol, 1-octanol and 1-heptanol) and alkenes (cyclohexene, styrene, ethyl benzene, 1-octene and 1-hexene) in a homogeneous catalytic system consisting t-butylhydroperoxide (TBHP) as an oxidant in acetonitrile. Both compounds exhibited very high activity in the oxidation of cyclohexene to cyclohexanone (~80% selectivity, ~99% conversion in 1?h, TOF?=?243?h?1 and 226?h?1) and cinnamyl alcohol to cinnamaldehyde (~64% selectivity) as the main product with very high TOF value (9180?h?1 and 13040?h?1 in the first minute of reaction) (~100% conversion in 0.5?h) with TBHP at 70?°C in acetonitrile, for 1 and 2, respectively.
- Su, Esra,Guven, Alaettin,Kani, Ibrahim
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- Chiral Manganese Aminopyridine Complexes: the Versatile Catalysts of Chemo- and Stereoselective Oxidations with H2O2
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In the last decade, manganese(II) complexes with N-donor tetradentate aminopyridine ligands emerged as efficient catalysts of enantioselective epoxidation of olefins and direct selective oxidation of C?H groups in complex organic molecules, with environmentally benign oxidant hydrogen peroxide. In this personal account, we summarize the progress of these catalysts with regard to ligands design, structure-reactivity correlations, evaluation of the substrate scope, as well as mechanistic studies, shedding light on the nature of active sites and the mechanisms of selective oxygenations. Several practically promising catalytic syntheses with the aid of Mn aminopyridine catalysts are exemplified.
- Ottenbacher, Roman V.,Talsi, Evgenii P.,Bryliakov, Konstantin P.
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- 1,1,2,2-Tetrahydroperoxy-1,2-Diphenylethane: An efficient and high oxygen content oxidant in various oxidative reactions
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Several oxidative approaches namely thiocyanation of aromatic compounds, epoxidation of alkenes, amidation of aromatic aldehydes, epoxidation of α β-unsaturated ketones, oxidation of sulfides to sulfoxides and sulfones, bayer-villeger reaction, bromination and iodation of aniline and phenol derivatives oxidative esterification, oxidation of pyridines and oxidation of secondary, allylic and benzyllic alcohols were carried out using 1,1,2,2-Tetrahydroperoxy-1,2-Diphenylethane as the potential solid oxidant which can be stored for several months without any loss in its activity. All of the procedures were accomplished via mild reaction conditions and the products were afforded in high yields and short reaction times.
- Khosravi, Kaveh,Naserifar, Shirin
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supporting information
p. 6584 - 6592
(2018/10/05)
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- Arylruthenium(III) Porphyrin-Catalyzed C-H Oxidation and Epoxidation at Room Temperature and [RuV(Por)(O)(Ph)] Intermediate by Spectroscopic Analysis and Density Functional Theory Calculations
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The development of highly active and selective metal catalysts for efficient oxidation of hydrocarbons and identification of the reactive intermediates in the oxidation catalysis are long-standing challenges. In the rapid hydrocarbon oxidation catalyzed by ruthenium(IV) and -(III) porphyrins, the putative Ru(V)-oxo intermediates remain elusive. Herein we report that arylruthenium(III) porphyrins are highly active catalysts for hydrocarbon oxidation. Using catalyst [RuIII(TDCPP)(Ph)(OEt2)] (H2TDCPP = 5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin), the oxidation of C-H bonds of various hydrocarbons with oxidant m-CPBA at room temperature gave alcohols/ketones in up to 99% yield within 1 h; use of [nBu4N]IO4 as a mild alternative oxidant avoided formation of lactone from cyclic ketone in C-H oxidation, and the catalytic epoxidation with up to 99% yield and high selectivity (no aldehydes as side product) was accomplished within 5 min. UV-vis, electrospray ionization-mass spectrometry, resonance Raman, electron paramagnetic resonance, and kinetic measurements and density functional theory calculations lend evidence for the formation of Ru(V)-oxo intermediate [RuV(TDCPP)(O)(Ph)].
- Shing, Ka-Pan,Cao, Bei,Liu, Yungen,Lee, Hung Kay,Li, Ming-De,Phillips, David Lee,Chang, Xiao-Yong,Che, Chi-Ming
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supporting information
p. 7032 - 7042
(2018/06/12)
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- A carboxylate-bridged Mn(II) compound with 6-methylanthranilate/bipy: oxidation of alcohols/alkenes and catalase-like activity
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A novel manganese compound, [Mn2(μ1,3-6-CH3-2-NH2C6H4COO)2(bipy)4](ClO4)2 (bipy?=?2,2′-bipyridine), was synthesized and used as a catalyst precursor in the oxidation of alkenes and primary alcohols to corresponding aldehydes, ketones, and acids. The six-coordinate compound has a binuclear structure in which two Mn(II) ions adopt a syn-anti μ1,3-bridging mode with two carboxylate groups and two chelated bipy ligands. The compound exhibits good activity in the oxidation of cyclohexene to 2-cyclohexene-1-one as the major product (93% conv. in 3?h, 79.3% selectivity) and of cinnamyl alcohol to cinnamaldehyde as the major product with 46% selectivity (100% conv. in 1.5?h) with tert-butyl hydroperoxide (TBHP) in acetonitrile at 70?°C. Furthermore, the catalase-like activity of the compound was studied in different solvents (acetonitrile, methanol, Tris-HCl buffer; TOF?=?29,910?h?1 in Tris-HCl buffer).
- Kilic, Yalcin,Bolat, Serkan,Kani, Ibrahim
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p. 2293 - 2303
(2018/05/14)
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- Metallophthalocyanine intercalated layered double hydroxides as an efficient catalyst for the selective epoxidation of olefin with oxygen
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Varied metallophthalocyanine intercalated layered double hydroxides (LDHs) as bifunctional hybrid catalysts for selective epoxidation have been prepared and characterized. Systematic characterizations suggested the successful intercalation of the metallophthalocyanines into the interlayer of ZnAl LDHs. The synthesized hybrid exhibited excellent catalytic activity in the selective epoxidation of various olefins through O2/isobutaldehyde system. The basicity of the hybrid benefits to the selectivity of epoxide, and the bifunctional roles of the catalyst in the reaction have been discussed and verified by a series of controlled experiments. On the basis of obtained results, a probable mechanism of the epoxidation by the hybrid has been proposed and detailedly investigated. Under the catalysis of metallophthalocyanines intercalated LDHs in the presence of O2/isobutaldehyde, the production of epoxide undergoes two reaction paths. And two types of intermediates, namely acylperoxy radical and peroxyacid, are formed in the reaction, and the former is predominant.
- Zhou, Weiyou,Zhou, Jiacheng,Chen, Yong,Cui, Aijun,Sun, Fu'an,He, Mingyang,Xu, Zhixiang,Chen, Qun
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p. 191 - 200
(2017/06/09)
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- Controllable Stereoselective Synthesis of (Z)- and (E)-Homoallylic Alcohols Using a Palladium-Catalyzed Three-Component Reaction
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Diastereoselective synthesis of (Z)- and (E)-homoallylic alcohols using a Pd-catalyzed three-component reaction of 3-(pinacolatoboryl)allyl benzoates, aldehydes, and aryl stannanes was developed, which provides an alternative method for the allylboration of aldehydes using α, γ-diaryl-substituted allylboronates. Both sets of reaction conditions enable access to either (Z)- or (E)-homoallylic alcohols with good to high alkene stereocontrol. The present method showed good functional group compatibility and generality. Efficient chirality transfer reactions to afford enantioenriched (Z)- and (E)-homoallylic alcohols were also achieved.
- Horino, Yoshikazu,Sugata, Miki,Mutsuura, Itaru,Tomohara, Keisuke,Abe, Hitoshi
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supporting information
p. 5968 - 5971
(2017/11/10)
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- Zinc-Mediated Efficient and Selective Reduction of Carbonyl Compounds
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We herein describe for the first time that an optimized combination of Zn and NH4Cl can be used for the selective reduction of aldehydes and ketones to the corresponding alcohols. The aldehyde and keto groups are selectively reduced in the presence of azide, cyano, epoxy, ester, and carbon–carbon double-bond functional groups. A broad functional-group compatibility, chemoselective reduction of aldehydes in the presence of ketones, and selective reduction of isatins at the C3 carbonyl group are the highlights of the present method.
- Mandal, Tirtha,Jana, Snehasish,Dash, Jyotirmayee
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p. 4972 - 4983
(2017/09/13)
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- Peroxotantalate-Based Ionic Liquid Catalyzed Epoxidation of Allylic Alcohols with Hydrogen Peroxide
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The efficient and environmentally benign epoxidation of allylic alcohols has been attained by using new kinds of monomeric peroxotantalate anion-functionalized ionic liquids (ILs=[P4,4,4,n]3[Ta(O)3(η-O2)], P4,4,4,n=quaternary phosphonium cation, n=4, 8, and 14), which have been developed and their structures determined accordingly. This work revealed the parent anions of the ILs underwent structural transformation in the presence of H2O2. The formed active species exhibited excellent catalytic activity, with a turnover frequency for [P4,4,4,4]3[Ta(O)3(η-O2)] of up to 285 h?1, and satisfactory recyclability in the epoxidation of various allylic alcohols under very mild conditions by using only one equivalent of hydrogen peroxide as an oxidant. NMR studies showed the reaction was facilitated through a hydrogen-bonding mechanism, in which the peroxo group (O–O) of the peroxotantalate anion served as the hydrogen-bond acceptor and hydroxyl group in the allylic alcohols served as the hydrogen-bond donor. This work demonstrates that simple monomeric peroxotantalates can catalyze epoxidation of allylic alcohols efficiently.
- Ma, Wenbao,Chen, Chen,Kong, Kang,Dong, Qifeng,Li, Kun,Yuan, Mingming,Li, Difan,Hou, Zhenshan
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p. 7287 - 7296
(2017/05/31)
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- One-pot epoxidation of alkenes using aerobic photoperoxidation of toluenes
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We developed an aerobic photooxidative synthesis of peroxybenzoic acids from toluenes using anthraquinone-2-carboxylic acid (AQN-2-CO2H) as a photocatalyst. We also found a one-pot epoxidation reaction of alkenes using 4-tert-butylperoxybenzoic acid produced in situ by aerobic photooxidative synthesis.
- Taguchi, Miyabi,Nagasawa, Yoshitomo,Yamaguchi, Eiji,Tada, Norihiro,Miura, Tsuyoshi,Itoh, Akichika
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supporting information
p. 230 - 232
(2015/12/31)
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- Highly Efficient Epoxidation of Allylic Alcohols with Hydrogen Peroxide Catalyzed by Peroxoniobate-Based Ionic Liquids
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This work reports new kinds of monomeric peroxoniobate anion functionalized ionic liquids (ILs) designated as [A+][Nb=O(O-O)(OH)2] (A+ = tetrapropylammonium, tetrabutylammonium, or tetrahexylammonium cation), which have been prepared and characterized by elemental analysis, HRMS, NMR, IR, TGA, etc. With hydrogen peroxide as an oxidant, these ILs exhibited excellent catalytic activity and recyclability in the epoxidation of various allylic alcohols under solvent-free and ice bath conditions. Interestingly, subsequent activity tests and catalyst characterization together with first-principles calculations indicated that the parent [Nb=O(O-O)(OH)2]- anion has been oxidized into the anion [Nb(O-O)2(OOH)2]- in the presence of H2O2, which constitutes the real catalytically active species during the reaction; this anion has higher activity in comparison to the analogous peroxotungstate anion. Moreover, the epoxidation process of the substrate (allylic alcohol) catalyzed by [Nb(O-O)2(OOH)2]- was explored at the atomic level by virtue of DFT (density functional theory) calculations, identifying that it is more favorable to occur through a hydrogen bond mechanism, in which the peroxo group of [Nb(O-O)2(OOH)2]- serves as the adsorption site to anchor the substrate OH group by forming a hydrogen bond, while OOH as the active oxygen species attacks the C=C bond in substrates to produce the corresponding epoxide. This is the first example of the highly efficient epoxidation of allylic alcohols using a peroxoniobate anion as a catalyst.
- Chen, Chen,Yuan, Haiyang,Wang, Haifeng,Yao, Yefeng,Ma, Wenbao,Chen, Jizhong,Hou, Zhenshan
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p. 3354 - 3364
(2016/07/06)
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- Asymmetric epoxidation of α,β-unsaturated aldehydes catalyzed by a spiro-pyrrolidine-derived organocatalyst
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The asymmetric epoxidation of α,β-unsaturated aldehydes, catalyzed by a spiro-pyrrolidine (SPD)-derived organocatalyst, has been accomplished with good diastereoselectivities (up to dr >20:1) and with high to excellent enantioselectivities (up to 99% ee).
- Xu, Ming-Hui,Tu, Yong-Qiang,Tian, Jin-Miao,Zhang, Fu-Min,Wang, Shao-Hua,Zhang, Shi-Heng,Zhang, Xiao-Ming
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supporting information
p. 294 - 300
(2017/03/01)
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- Effective catalytic oxidation of alcohols and alkenes with monomeric versus dimeric manganese(II) catalysts and t-BuOOH
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Two new Mn(II) complexes, [Mn(C6H5COO)(H2O)(phen)2](ClO4)(CH3OH) (1) and [Mn2(μ-C6H5COO)2(bipy)4]?2(ClO4) (2) (phen = 1,10-phenanthroline; bipy = 2,2′-bipyridine), were synthesized and characterized using UV–visible and infrared spectroscopies and single-crystal X-ray diffraction analyses. Complexes 1 and 2 have six-coordinate octahedral geometry around the Mn(II) centre. Complex 1 is a monomer and consists of a deprotonated monodentate benzoate ligand together with two neutral bidentate amine ligands (phen) and a water molecule. Complex 2 has a dinuclear structure in which two Mn(II) ions share two carboxylate groups, adopting a two-atom bridging mode, and two chelated bipy ligands. Both complexes catalyse the oxidation of alcohols and alkenes in a homogeneous catalytic system consisting of the Mn(II) complex and tert-butyl hydroperoxide (TBHP) in acetonitrile. The system yields good to quantitative conversions of various alkenes and alcohols, such as styrene, ethylbenzene and cyclohexene to their corresponding ketones, and primary alcohols and 1-octanol, 1-heptanol, cyclohexanol, benzyl alcohols and cinnamyl alcohol to their corresponding aldehydes and carboxylic acids. Complexes 1 and 2 exhibit very high activity in the oxidation of cyclohexene to cyclohexanone (ca 80% selectivity) as the main product (ca 94% conversion in 1 h) and of cinnamyl alcohol to cinnamaldehyde (ca 64% selectivity) as the main product (ca 100% conversion in 0.5 h) with TBHP at 70°C in acetonitrile. In addition, optimum reaction conditions were also determined for benzyl alcohol with complexes 1 and 2 and TBHP.
- Kani, Ibrahim,Bolat, Serkan
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p. 713 - 721
(2016/07/19)
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- Highly efficient transformation of alcohol to carbonyl compounds under a hybrid bifunctional catalyst originated from metalloporphyrins and hydrotalcite
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The development of a highly active and selective catalytic system that is economical, environmentally benign, and easily recoverable is highly desirable. Bifunctional hybrid catalysts originated from metalloporphyrins (MTSPP; M = Co, Fe, and Mn), and hydrotalcite have been synthesized, characterized, and investigated in the aerobic oxidation of alcohols in the presence of isobutyraldehyde. The designed catalysts exhibited excellent activity, broad applicable scope, and good stability in the oxidation. The effect of surface basicity on the catalytic performance has been studied in detail. The research results showed that as well as protecting the metalloporphyrin molecule, the surface basicity of hydrotalcite also contributed to improving the catalytic activity and the selectivity of aldehyde, and a synergistic effect was observed in the catalytic system. A proposed mechanism for the reaction involving the formation of high-valence cobalt-oxo porphyrin intermediate was postulated based on catalytic results and Hammett and H218O experiments.
- Zhou, Wei-You,Tian, Peng,Sun, Fu'An,He, Ming-Yang,Chen, Qun
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p. 105 - 116
(2016/01/26)
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- Immobilized V-MIL-101 on modified Fe3O4 nanoparticles as heterogeneous catalyst for epoxidation of allyl alcohols and alkenes
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As a new heterogeneous catalyst, Fe3O4 nanoparticles were prepared and modified with sodium silicate and (3-aminopropyl) trimethoxysilane (APTMS) followed by complexation with V-MIL-101 and designated as Fe3O4@SiO2@APTMS@VMIL-101. It was characterized using FTIR, TEM, and VSM techniques. The Fe3O4@SiO2@APTMS@VMIL-101 was found to successfully catalyze the epoxidation of allyl alcohols and alkenes with tert-butylhydroperoxide (TBHP) in moderate to high yields. The epoxidation of trans-stilbene, norbornen, cyclooctene, geraniol, trans-2-hexene-1ol and 1-octene-3-ol with 100% selectivity is promising. Investigation of the stability and reusability of Fe3O4@SiO2@APTMS@V-MIL-101 revealed the heterogeneity character of the catalyst with no desorption during the course of epoxidation reactions. High yields, clean reactions, ease of catalyst separation and recyclability of the solid catalyst are some advantages of this method.
- Farzaneh, Faezeh,Sadeghi, Yasaman
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p. 275 - 281
(2015/03/03)
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- Sensing remote chirality: Stereochemical determination of β-, γ-, and δ-chiral carboxylic acids
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Determining the absolute stereochemisty of small molecules bearing remote nonfunctionalizable stereocenters is a challenging task. Presented is a solution in which appropriately substituted bis(porphyrin) tweezers are used. Complexation of a suitably derivatized β-, γ-, or δ-chiral carboxylic acid to the tweezer induces a predictable helicity of the bis(porphyrin), which is detected as a bisignate Cotton Effect (ECCD). The sign of the ECCD curve is correlated with the absolute stereochemistry of the substrate based on the derived working mnemonics in a predictable manner.
- Tanasova, Marina,Anyika, Mercy,Borhan, Babak
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supporting information
p. 4274 - 4278
(2015/04/14)
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- Asymmetric syntheses of three-membered heterocycles using chiral amide-based ammonium ylides
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The use of carbonyl-stabilised ammonium ylides to access chiral glycidic amides and the corresponding aziridines has so far been limited to racemic trans-selective protocols. We herein report the development of an asymmetric approach to access such compou
- Pichler, Mathias,Novacek, Johanna,Robiette, Raphal,Poscher, Vanessa,Himmelsbach, Markus,Monkowius, Uwe,Müller, Norbert,Waser, Mario
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p. 2092 - 2099
(2015/03/05)
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- Asymmetric epoxidation of allylic alcohols catalyzed by vanadium-binaphthylbishydroxamic acid complex
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A vanadium-binaphthylbishydroxamic acid (BBHA) complex-catalyzed asymmetric epoxidation of allylic alcohols is described. The optically active binaphthyl-based ligands BBHA 2a and 2b were synthesized from (S)-1,1'-binaphthyl-2,2'dicarboxylic acid and N-substituted-O-trimethylsilyl (TMS)-protected hydroxylamines via a one-pot, three-step procedure. The epoxidations of 2,3,3-trisubstituted allylic alcohols using the vanadium complex of 2a were easily performed in toluene with a TBHP water solution to afford (2R)-epoxy alcohols in good to excellent enantioselectivities.
- Noji, Masahiro,Kobayashi, Toshihiro,Uechi, Yuria,Kikuchi, Asami,Kondo, Hisako,Sugiyama, Shigeo,Ishii, Keitaro
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supporting information
p. 3203 - 3210
(2015/03/30)
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- Cis-2,6-Bis-(methanolate)-piperidine oxovanadium(V) complexes as catalysts for oxidative alkenol cyclization by tert-butyl hydroperoxide
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cis-2,6-Bis-(methanolate)-piperidine oxovanadium(V) complexes are Lewis acids able to catalyze oxidative cyclization of alkenols by tert-butyl hydroperoxide (TBHP). Terminal dimethyl-substituted (prenyl-type) 4-pentenols bearing an alkyl or a phenyl group in position 1 afford under such conditions 2,5-cis-derivatives of 2-(tetrahydrofuran-2-yl)-2-propanol as major and tetrahydropyran-3-ols as minor products (four examples). Oxidizing 1-phenyl-6-methylhept-5-en-1-ol yields a 75/25-mixture of the derived 2-(tetrahydropyran-2-yl)-2-propanol and an oxepan-3-ol, whereas 2-propenols give epoxides in up to 94% yield. Epoxidizing geraniol by TBHP in the presence of a vanadium catalyst prepared from (2S,6R)-2-diphenylmethanol-6- hydroxymethylpiperidine occurs enantioselectively. Highfield shifts of vanadium-51 resonances upon adding alkyl hydroperoxides to solutions of cis-2,6-bis-(methanolate)-piperidine vanadium(V) complexes point to vanadium(V) tert-butyl peroxy complex formation as key step for activating peroxides.
- D?nges, Maike,Amberg, Matthias,Stapf, Georg,Kelm, Harald,Bergstr??er, Uwe,Hartung, Jens
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p. 120 - 134
(2014/07/08)
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- Synthesis and structure-activity relationship study of substituted caffeate esters as antinociceptive agents modulating the TREK-1 channel
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The TWIK-related K+ channel, TREK-1, has recently emerged as an attractive therapeutic target for the development of a novel class of analgesic drugs. It has been reported that TREK-1 -/- mice were more sensitive than wild-type mice to painful stimuli, suggesting that activation of TREK-1 could result in pain inhibition. Here we report the synthesis of a series of substituted caffeate esters (12a-u) based on the hit compound CDC 2 (cinnamyl 3,4-dihydroxyl-α-cyanocinnamate). These analogs were evaluated for their ability to modulate TREK-1 channel by electrophysiology and for their in vivo antinociceptive activity (acetic acid induced-writhing assay) leading to the identification a series of novel molecules able to activate TREK-1 and displaying potent analgesic activity in vivo.
- Rodrigues, Nuno,Bennis, Khalil,Vivier, Delphine,Pereira, Vanessa,Chatelain, Franck C.,Chapuy, Eric,Deokar, Hemantkumar,Busserolles, Jér?me,Lesage, Florian,Eschalier, Alain,Ducki, Sylvie
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supporting information
p. 391 - 402
(2014/03/21)
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- BICYCLIC HETEROCYCLE SUBSTITUTED PYRIDYL COMPOUNDS USEFUL AS KINASE MODULATORS
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Compounds having the following formula (I) or a stereoisomer or a pharmaceutically-acceptable salt thereof, wherein R2 is a bicyclic heterocycle, and R1, R3, R4, R5 and R6 are as defined herein, that are useful as kinase modulators, including IRAK-4 modulation.
- -
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Paragraph 00250
(2014/05/24)
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- HETEROARYL SUBSTITUTED PYRIDYL COMPOUNDS USEFUL AS KINASE MODULATORS
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Compounds having the following formula (I) or a stereoisomer or a pharmaceutically-acceptable salt thereof, wherein R2 is a monocyclic heteroaryl group, and R1, R3, R4, R5 and R6 are as defined herein, are useful as kinase modulators, including IRAK-4 inhibition.
- -
-
Paragraph 00198
(2019/03/15)
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- Bioresolution production of (2R,3S)-Ethyl-3-phenylglycidate for chemoenzymatic synthesis of the taxol C-13 side chain by galactomyces geotrichum ZJUTZQ200, a new epoxide-hydrolase-producing strain
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A newly isolated Galactomyces geotrichum ZJUTZQ200 strain containing an epoxide hydrolase was used to resolve racemic ethyl 3-phenylglycidate (rac-EPG) for producing (2R,3S)-ethyl-3-phenylglycidate ((2R,3S)-EPG). G. geotrichum ZJUTZQ200 was verified to be able to afford high enantioselectivity in whole cell catalyzed synthesis of this chiral phenylglycidate synthon. After the optimization of the enzymatic production and bioresolution conditions, (2R,3S)-EPG was afforded with high enantioselectivity (e.e.S > 99%, E > 49) after a 8 h reaction. The co-solvents, pH buffer solutions and substrate/cell ratio were found to have significant influences on the bioresolution properties of G. geotrichum ZJUTZQ200. Based on the bioresolution product (2R,3S)-EPG, taxol's side chain ethyl (2R,3S)-3-benzoylamino-2-hydroxy- 3-phenylpropionate was successfully synthesized by a chemoenzymatic route with high enantioselectivity (e.e.S > 95%).
- Wei, Chun,Ling, Jinlong,Shen, Honglei,Zhu, Qing
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p. 8067 - 8079
(2014/07/08)
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- Function-oriented investigations of a peptide-based catalyst that mediates enantioselective allylic alcohol epoxidation.
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We detail an investigation of a peptide-based catalyst (6) that is effective for the site- (>100 - 1 - 1) and enantioselective epoxidation (86% ee) of farnesol. Studies of the substrate scope exhibited by the catalyst are included, along with an exploration of optimized reaction conditions. Mechanistic studies are reported, including relative rate determinations for the catalyst and propionic acid, a historical perspective, truncation studies, and modeling using NMR data. Our compiled data advances our understanding of the inner workings of a catalyst that was identified through combinatorial means.
- Abascal, Nadia C.,Lichtor, Phillip A.,Giuliano, Michael W.,Miller, Scott J.
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p. 4504 - 4511
(2015/02/19)
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- Tungsten-catalyzed regio- and enantioselective aminolysis of trans-2,3-epoxy alcohols: An entry to virtually enantiopure amino alcohols
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The first catalytic enantioselective aminolysis of trans-2,3-epoxy alcohols has been accomplished. This stereo-specific ring-opening process was efficiently promoted by a tungsten/bis(hydroxamic acid) catalytic system, furnishing various anti-3-amino-1,2-diols with excellent regiocontrol and high enantioselectivities (up to 95% ee). Moreover, virtually enantiopure 3-amino-1,2-diols could be obtained by the sequential combination of two reactions that both involve the use of a chiral catalyst.
- Wang, Chuan,Yamamoto, Hisashi
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supporting information
p. 13920 - 13923
(2015/02/05)
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- Tungsten-catalyzed asymmetric epoxidation of allylic and homoallylic alcohols with hydrogen peroxide
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A simple, efficient, and environmentally friendly asymmetric epoxidation of primary, secondary, tertiary allylic, and homoallylic alcohols has been accomplished. This process was promoted by a tungsten-bishydroxamic acid complex at room temperature with the use of aqueous 30% H2O2 as oxidant, yielding the products in 84-98% ee.
- Wang, Chuan,Yamamoto, Hisashi
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supporting information
p. 1222 - 1225
(2014/02/14)
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- Improved synthesis of structural analogues of (-)-epicatechin gallate for modulation of staphylococcal β-lactam resistance
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The high-yielding synthesis of enantiomerically pure epicatechin gallate analogues where the A and/or B-ring hydroxylation is reduced or altered has been achieved by optimising routes to the catechin stereochemistry. The B-ring analogues were synthesised by using an electrophilic ring closure onto an enantiomerically enriched epoxide as a key step. The A and B-ring hydroxyl-deleted analogues were synthesised through a Mitsunobu cyclisation. For the B-ring analogues, the anti- (catechin) stereochemistry was converted to the syn- (epicatechin) stereochemistry by a known oxidation/reduction protocol. Absolute stereochemistry was derived from either a Sharpless epoxidation or asymmetric dihydroxylation.
- Anderson, James C.,Grounds, Helen,Reeves, Suzanna,Taylor, Peter W.
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p. 3485 - 3490
(2014/05/06)
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- Unusually Broad Substrate Profile of Self-Sufficient Cytochrome P450 Monooxygenase CYP116B4 from Labrenzia aggregata
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A new member of the CYP116B subfamily - P450LaMO - was discovered in Labrenzia aggregata by genomic data mining. It was successfully overexpressed in Escherichia coli, purified, and subsequently characterized spectroscopically, and its catalytic properties were assessed. Substrate profiling of the P450LaMO revealed that it was a versatile catalyst, exhibiting hydroxylation and epoxidation activities as well as O-dealkylation and asymmetric sulfoxidation activities. Diverse compounds, including alkylbenzenes, aromatic bicyclic molecules, and terpenoids, were shown to be hydroxylated by P450LaMO. Such diverse catalytic activities are uncommon for the bacterial P450s, and the P450LaMO -mediated stereoselective hydroxylation of inactivated C - H bonds - ubiquitous and relatively unreactive in organic molecules - is particularly unusual. The self-sufficient nature of P450LaMO, coupled with its broad substrate range, highlights it as an ideal template for directed evolution towards various applications.
- Yin, Yue-Cai,Yu, Hui-Lei,Luan, Zheng-Jiao,Li, Ren-Jie,Ouyang, Peng-Fei,Liu, Jing,Xu, Jian-He
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p. 2443 - 2449
(2015/03/03)
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