- Oxygenation of alkenes with t-BuOOH catalysed by β-cyclodextrin borate
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β-Cyclodextrin borate catalyses oxygenation of aryl substituted alkenes in the presence of t-BuOOH to afford β-dioxy alcohols in good yields (63-86%).
- Bhat, Shridhar,Chandrasekaran, Srinivasan
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- Microbiological transformations. 31: Synthesis of enantiopure epoxides and vicinal diols using fungal epoxide hydrolase mediated hydrolysis
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The enantioselective hydrolysis of epoxyindene and dihydronaphtalene epoxides by the fungus Beauveria sulfurescens (ATCC 7159) is described. This allowed the preparation of both these epoxides, as well as of the corresponding diols, in good to excellent enantiomeric purity.
- Pedragosa-Moreau,Archelas,Furstoss
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- β-Hydroxy carbocation intermediates in solvolyses of di- and tetra-hydronaphthalene substrates
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Solvolysis of trichloroacetate esters of 2-methoxy-1,2-dihydro-1-naphthols shows a remarkably large difference in rates between the cis and trans isomers, kcis/ktrans = 1800 in aqueous acetonitrile. This mirrors the behaviour of the acid-catalysed dehydration of cis- and trans-naphthalene-1, 2-dihydrodiols to form 2-naphthol, for which kcis/ktrans = 440, but contrasts with that for solvolysis of tetrahydronaphthalene substrates, 1-chloro-2-hydroxy-1,2,3,4-tetrahydronaphthalenes, for which k cis/ktrans = 0.5. Evidence is presented showing that the trans isomer of the dihydro substrates reacts unusually slowly rather than the cis isomer unusually rapidly. Comparison of rates of solvolysis of 1-chloro-1,2,3,4-tetrahydronaphthalene and the corresponding (cis) substrate with a 2-hydroxy group indicates that a β-OH slows the reaction by nearly 2000-fold, which represents a typical inductive effect characteristic also of cis-dihydrodiol substrates. The slow reaction of the trans-dihydrodiol substrate is consistent with initial formation of a β-hydroxynaphthalenium carbocation with a conformation in which a C-OH occupies an axial position β to the carbocation centre preventing stabilisation of the carbocation by C-H hyperconjugation, which would occur in the conformation initially formed from the cis isomer. It is suggested that C-H hyperconjugation is particularly pronounced for a β-hydroxynaphthalenium ion intermediate because the stability of its no-bond resonance structure reflects the presence of an aromatic naphthol structure.
- Kudavalli, Jaya S.,More O'Ferrall, Rory A.
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- Verification of the Major Metabolic Oxidation Path for the Naphthoyl Group in Chemoattractant Receptor-Homologous Molecule Expressed on Th2 Cells (CRTh2) Antagonist 2-(2-(1-Naphthoyl)-8-fluoro-3,4-dihydro-1H-pyrido[4,3-b]indol-5(2H)-yl)acetic Acid (Setipiprant/ACT-129968)
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Various racemic and enantioenriched (trans)-X,Y-dihydroxy-X,Y-dihydronaphthoyl analogues as well as X-hydroxy-naphthoyl analogues of CRTh2 antagonist 2-(2-(1-naphthoyl)-8-fluoro-3,4-dihydro-1H-pyrido[4,3-b]indol-5(2H)-yl)acetic acid (1, Setipiprant/ACT-129968) were synthesized in order to gain insight into regio- and enantioselectivity of the metabolic oxidation of 1 and to verify the structures of four metabolites that were proposed earlier in a clinical ADME study. Analytical data of the synthetic standards were compared with data from samples of biological origin. The two major metabolites M7 and M9 were unambiguously verified as 2-(2-((trans)-3,4-dihydroxy-3,4-dihydronaphthalene-1-carbonyl)- and 2-(2-((trans)-5,6-dihydroxy-5,6-dihydronaphthalene-1-carbonyl)-8-fluoro-3,4-dihydro-1H-pyrido[4,3-b]indol-5(2H)-yl)acetic acid, respectively, each composed of two enantiomers with 68% and 44% ee in favor of (+)-(3S,4S)-M7 and (+)-(5S,6S)-M9, respectively. Likewise, minor metabolites M3 and M13 were identified as 2-(8-fluoro-2-(5-hydroxy-1-naphthoyl)- and 2-(8-fluoro-2-(4-hydroxy-1-naphthoyl)-1,2,3,4-tetrahydro-5H-pyrido[4,3-b]indol-5-yl)acetic acid, respectively.
- Risch, Philippe,Pfeifer, Thomas,Segrestaa, Jerome,Fretz, Heinz,Pothier, Julien
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- New chiral synthons from the microbial oxidation of bromonaphthalenes
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1-Bromo- and 2-bromonaphthalene were subjected to bio-oxidation with whole cells of Pseudomonas putida NCIB 9816-11. The major metabolites were isolated and spectroscopically characterized as (+)-cis-(1R,2S)-Dihydroxy-1,2-dihydro-8-bromonaphthalene 1, (+)-cis-(1R,2S)-Dihydroxy-1,2-dihydro-5-bromonaphthalene 2 from 1-bromonaphthalene and (+)-cis-(1R,2S)-Dihydroxy-1,2-dihydro-7-bromonaphthalene 8 from 2-bromonaphthalene. The absolute stereochemistry and enantiomeric excess were determined by conversion of each metabolite to the known (-)-cis-tetrahydronaphthalene diol 6.
- Hudlicky, Tomas,Endoma, Mary Ann A.,Butora, Gabor
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- A de novo synthetic method to the access of N-substituted benzazepines
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A novel, convenient procedure has been described for the construction of fluorine-containing benzazepines. The synthetic protocol starting from readily available dihydronaphthalene regioisomers is based on oxidative ring olefin bond cleavage followed by r
- Ouchakour, Lamiaa,Nonn, Melinda,D'hooghe, Matthias,Kiss, Loránd
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- Enantioselective, Stereoconvergent Resolution Copolymerization of Racemic cis-Internal Epoxides and Anhydrides
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Unprecedented enantioselective resolution copolymerization of racemic cis-internal epoxides and anhydrides was mediated by dinuclear aluminum complexes with multiple chirality, affording optically active polyesters with two contiguous stereogenic centers, and the unreacted substrates in good enantioselectivity. Unexpected stereoconvergence is observed in this resolution copolymerization, where the selectivity factor for the enantioselective formation of copolymer significantly exceeds the kinetic resolution coefficient based on the unreacted epoxide at various conversions. Catalytic activity and copolymer enantioselectivity are strongly influenced by the phenolate ortho-substituents of the ligand set, as well as the axial linker and its chirality. An enantiopure binaphthol-linked bimetallic AlIII complex allows stereoconvergent access to the stereoregular semi-crystalline polyesters and a concomitant kinetic resolution of the epoxide substrates.
- He, Guang-Hui,Ren, Bai-Hao,Chen, Shi-Yu,Liu, Ye,Lu, Xiao-Bing
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p. 5994 - 6002
(2021/02/11)
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- Iodine-Initiated Dioxygenation of Aryl Alkenes Using tert-Butylhydroperoxides and Water: A Route to Vicinal Diols and Bisperoxides
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An environment-friendly and efficient dioxygenation of aryl alkenes for the construction of vicinal diols has been developed in water with iodine as the catalyst and tert-butylhydroperoxides (TBHPs) as the oxidant. The protocol was efficient, sustainable, and operationally simple. Detailed mechanistic studies indicated that one of the hydroxyl groups is derived from water and the other one is derived from TBHP. Additionally, the bisperoxides could be obtained in good yields with iodine as the catalyst, Na2CO3 as the additive, and propylene carbonate as the solvent, instead.
- Gao, Xiaofang,Lin, Jiani,Zhang, Li,Lou, Xinyao,Guo, Guanghui,Peng, Na,Xu, Huan,Liu, Yi
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p. 15469 - 15480
(2021/11/16)
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- Regioselective biocatalytic self-sufficient Tishchenko-type reactionviaformal intramolecular hydride transfer
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A self-sufficient nicotinamide-dependent intramolecular bio-Tishchenko-type reaction was developed. The reaction is catalyzed by alcohol dehydrogenases and proceeds through formal intramolecular hydride transfer on dialdehydes to deliver lactones. Regioselectivity on [1,1′-biphenyl]-2,2′-dicarbaldehyde substrates could be controlledviathe electronic properties of the substituents. Preparative scale synthesis provided access to substituted dibenzo[c,e]oxepin-5(7H)-ones.
- Buljubasic, Isa,Hall, Mélanie,Laggner, Olivia,Merusic, Kemal,Reiter, Tamara,Tassano, Erika,Vogel, Andreas
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supporting information
p. 6340 - 6343
(2020/06/21)
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- Oxidative β-Halogenation of Alcohols: A Concise and Diastereoselective Approach to Halohydrins
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β-Halohydrins bearing transformable halo- and hydroxyl groups, are easily converted into various valuable blocks in organic and pharmaceutical synthesis. A diastereoselective β-halogenation of benzylic alcohols was achieved under simple and low-cost conditions, which provided a direct synthesis of β-halohydrins. The simple reaction conditions, easily available reagents, high diastereoselectivities, and additional oxidant-free make this reaction very attractive and practical.
- Ai, Lingsheng,Wang, Weijin,Wei, Jialiang,Li, Qing,Song, Song,Jiao, Ning
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supporting information
p. 437 - 441
(2019/02/26)
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- Multivariate Metal-Organic Frameworks as Multifunctional Heterogeneous Asymmetric Catalysts for Sequential Reactions
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The search for versatile heterogeneous catalysts with multiple active sites for broad asymmetric transformations has long been of great interest, but it remains a formidable synthetic challenge. Here we demonstrate that multivariate metal-organic frameworks (MTV-MOFs) can be used as an excellent platform to engineer heterogeneous catalysts featuring multiple and cooperative active sites. An isostructural series of 2-fold interpenetrated MTV-MOFs that contain up to three different chiral metallosalen catalysts was constructed and used as efficient and recyclable heterogeneous catalysts for a variety of asymmetric sequential alkene epoxidation/epoxide ring-opening reactions. Interpenetration of the frameworks brings metallosalen units adjacent to each other, allowing cooperative activation, which results in improved efficiency and enantioselectivity over the sum of the individual parts. The fact that manipulation of molecular catalysts in MTV-MOFs can control the activities and selectivities would facilitate the design of novel multifunctional materials for enantioselective processes.
- Xia, Qingchun,Li, Zijian,Tan, Chunxia,Liu, Yan,Gong, Wei,Cui, Yong
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supporting information
p. 8259 - 8266
(2017/06/28)
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- Production Of Enantiopure alpha-Hydroxy Carboxylic Acids From Alkenes By Cascade Biocatalysis
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The invention provides compositions comprising an alkene epoxidase and a selective epoxide hydrolase, such as a recombinant microorganism comprising a first heterologous nucleic acid encoding an alkene epoxidase and a second heterologous nucleic acid encoding a selective epoxide hydrolase. Exemplary alkene epoxidases include StyAB, while exemplary selective epoxide hydrolases include epoxide hydrolases from Sphingomonas, Solanum tuberosum, or Aspergillus. The invention also provides non-toxic methods of making enantiomerically pure vicinal diols or enantiomerically pure alpha-hydroxy carboxylic acids using these compositions and microorganisms.
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Paragraph 0091-0093
(2016/05/02)
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- Alkene anti-Dihydroxylation with Malonoyl Peroxides
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Malonoyl peroxide 1, prepared in a single step from the commercially available diacid, is an effective reagent for the anti-dihydroxylation of alkenes. Reaction of 1 with an alkene in the presence of acetic acid at 40 °C followed by alkaline hydrolysis leads to the corresponding diol (35-92%) with up to 13:1 anti-selectivity. A mechanism consistent with experimental findings is proposed that accounts for the selectivity observed.
- Alamillo-Ferrer, Carla,Davidson, Stuart C.,Rawling, Michael J.,Theodoulou, Natalie H.,Campbell, Matthew,Humphreys, Philip G.,Kennedy, Alan R.,Tomkinson, Nicholas C. O.
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supporting information
p. 5132 - 5135
(2015/11/03)
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- A facile synthesis of vicinal cis-diols from olefins catalyzed by in situ generated MnxOy nanoaggregates
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A novel protocol for the practical and green synthesis of vicinal cis-diols from 10.0 mmol olefins by using 5.0 mmol KMnO4 as oxidant and 30.0 mmol H2O2 as co-oxidant is reported. The presented procedure is easy to carry out and enables the direct transformation of linear and cyclic alkenes to the corresponding vicinal cis-diols. The synthesis of vicinal cis-diols by dihydroxylation of olefins with a KMnO4/H2O2 system was catalyzed by in situ generated MnxOy nanoaggregates. The use of H2O2 as a co-oxidant is the key for the protocol to synthesize vicinal cis-diols in high yields, because it assists the oxidation of MnxOy nanoaggregates, which have an active role in the oxidation reaction medium.
- Dalmizrak, Di?dem,G?ksu, Haydar,Gültekin, Mehmet Serdar
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p. 20751 - 20755
(2015/03/18)
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- Enantioselective Cascade Biocatalysis via Epoxide Hydrolysis and Alcohol Oxidation: One-Pot Synthesis of (R)-α-Hydroxy Ketones from Meso- or Racemic Epoxides
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A new type of cascade biocatalysis was developed for one-pot enantioselective conversion of a meso- or racemic epoxide to an α-hydroxy ketone in high ee via an epoxide hydrolase-catalyzed hydrolysis of the epoxide, an alcohol dehydrogenase-catalyzed oxidation of the diol intermediate, and an enzyme-catalyzed cofactor regeneration. In vitro cascade biotransformation of meso-epoxides (cyclopentene oxide 1a, cyclohexene oxide 1b, and cycloheptene oxide 1c) was achieved with cell-free extracts containing recombinant SpEH (epoxide hydrolase from Sphingomonas sp. HXN-200), BDHA (butanediol dehydrogenase from Bacillus subtilis BGSC1A1), and LDH (lactate dehydrogenase form Bacillus subtilis) or NOX (NADH oxidase from Lactobacillus brevis DSM 20054), respectively, giving the corresponding (R)-α-hydroxycyclopentanone 3a, (R)-α-hydroxycyclohexanone 3b, and (R)-α-hydroxycycloheptanone 3c in 98-99% ee and 70-50% conversion with TTN of NAD+-recycling of 5500-26000. Cascade catalysis with mixed cells of Escherichia coli (SpEH) and E. coli (BDHA-NOX) converted 100-300 mM meso-epoxides 1a-1c to (R)-α-hydroxy ketones 3a-3c in 98-99% ee and 85-57% conversion. Cells of E. coli (SpEH-BDHA-NOX) coexpressing all three enzymes were also proven as good catalysts for the cascade conversion of 100-200 mM meso-epoxides 1a-1c, giving (R)-α-hydroxy ketones 3a-3c in 98-99% ee and 79-52% conversion. The cascade biocatalysis for one-pot synthesis of α-hydroxy ketone in high ee was also successfully demonstrated with a racemic epoxide (1,2,3,4-tetrahydronaphthalene-1,2-oxide 1d) as the substrate. By using two whole-cells based approaches, (R)-α-hydroxytetralone 3d was obtained in 99% ee and 49-40% conversion from 20 to 5 mM racemic epoxide 1d. Preparative cascade biotransformation of cyclohexene oxide 1b gave (R)-α-hydroxycyclohexanone 3b in 98% ee with 70% isolated yield. The developed new type of cascade biocatalysis is enantioselective, green, and often high yielding. The concept might be generally applicable to produce other useful enantiopure α-hydroxy ketones from the corresponding meso- or racemic epoxides by cascade catalysis using appropriate enzymes. (Chemical Equation Presented).
- Zhang, Jiandong,Wu, Shuke,Wu, Jinchuan,Li, Zhi
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- Chemoenzymatic epoxidation of alkenes based on peracid formation by a Rhizomucor miehei lipase-catalyzed perhydrolysis reaction
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A chemoenzymatic and selective method for the epoxidation of a series of cyclic and linear alkenes is described. Epoxides have been obtained in moderate to excellent conversions under mild reaction conditions through a two-step sequence, carried out in one-pot. This chemoenzymatic approach is based on a Rhizomucor miehei lipase-catalyzed perhydrolysis reaction to form the corresponding peracid, and subsequent epoxidation of the corresponding alkenes. Reaction parameters with influence in the biotransformation have been optimized specially focusing in the efficient enzymatic peracid formation by means of the correct choice of solvent, oxidant, and peracid precursor. This chemoenzymatic approach has been efficiently applied for the first time, in the regioselective chemical oxidation of (S)-carvone and limonene, both showing an opposite behavior for the oxidation of the internal and external C-C double bond, respectively.
- Méndez-Sánchez, Daniel,Ríos-Lombardía, Nicolás,Gotor, Vicente,Gotor-Fernández, Vicente
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p. 1144 - 1148
(2014/02/14)
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- Enantioselective trans-dihydroxylation of aryl olefins by cascade biocatalysis with recombinant escherichia coli coexpressing monooxygenase and epoxide hydrolase
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Cascade biocatalysis via intracellular epoxidation and hydrolysis was developed as a green and efficient method for enantioselective dihydroxylation of aryl olefins to prepare chiral vicinal diols in high ee and high yield. Escherichia coli (SSP1) coexpressing styrene monooxygenase (SMO) and epoxide hydrolase SpEH was developed as a simple and efficient biocatalyst for S-enantioselective dihydroxylation of terminal aryl olefins 1a-15a to give (S)-vicinal diols 1c-15c in high ee (97.5-98.6% for 10 diols; 92.2-93.9% for 3 diols) and high yield (91-99% for 6 diols; 86-88% for 2 diols; 67% for 3 diols). Combining SMO and epoxide hydrolase StEH showing complementary regioselectivity to SpEH as a biocatalyst for the cascade biocatalysis gave rise to R-enantioselective dihydroxylation of aryl olefins, being the first example of this kind of reversing the overall enantioselectivity of cascade biocatalysis. E. coli (SST1) coexpressing SMO and StEH was also engineered as a green and efficient biocatalyst for R-dihydroxylation of terminal aryl olefins 1a-15a to give (R)-vicinal diols 1c-15c in high ee (94.2-98.2% for 7 diols; 84.2-89.9% for 6 diols) and high yield (90-99% for 6 diols; 85-89% for 5 diols; 65% for 1 diol). E. coli (SSP1) and E. coli (SST1) catalyzed the trans-dihydroxylation of trans-aryl olefin 16a and cis-aryl olefin 17a with excellent and complementary stereoselectivity, giving each of the four stereoisomers of 1-phenyl-1,2- propanediol 16c in high ee and de, respectively. Both strains catalyzed the trans-dihydroxylation of aryl cyclic olefins 18a and 19a to afford the same trans-cyclic diols (1R,2R)-18c and (1R,2R)-19c, respectively, in excellent ee and de. This type of cascade biocatalysis provides a tool that is complementary to Sharpless dihydroxylation, accepting cis-alkene and offering enantioselective trans-dihydroxylation.
- Wu, Shuke,Chen, Yongzheng,Xu, Yi,Li, Aitao,Xu, Qisong,Glieder, Anton,Li, Zhi
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p. 409 - 420
(2014/03/21)
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- Heterogenisation of ketone catalysts within mesoporous supports for asymmetric epoxidation
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The synthesis of the first mesoporous silica (150 A) anchored carbohydrate-derived chiral ketone is described. This new heterogeneous catalyst has been shown to be effective in the asymmetric epoxidation of olefins by oxone. The heterogeneous ketone catalyst has comparable activity to that of its homogeneous counterpart and returned enantioselectivities up to 90% e.e.
- Brown, Lynda J.,Brown, Richard C. D.,Raja, Robert
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p. 843 - 850
(2013/03/28)
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- Enantioselective biooxidation of racemic trans-cyclic vicinal diols: One-pot synthesis of both enantiopure (S,S)-cyclic vicinal diols and (R)-α-hydroxy ketones
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Highly regio- and enantioselective alcohol dehydrogenases BDHA (2,3-butanediol dehydrogenase from Bacillus subtilis BGSC1A1), CDDHPm (cyclic diol dehydrogenase from Pseudomonas medocina TA5), and CDDHRh (cyclic diol dehydrogenase from Rhodococcus sp. Moj-3449) were discovered for the oxidation of racemic trans-cyclic vicinal diols. Recombinant Escherichia coli expressing BDHA was engineered as an efficient whole-cell biocatalyst for the oxidation of (±)-1,2-cyclopentanediol, 1,2-cyclohexanediol, 1,2-cycloheptane-diol, and 1,2-cyclooctanediol, respectively, to give the corresponding (R)-α-hydroxy ketones in >99% ee and (S,S)-cyclic diols in >99% ee at 50% conversion in one pot. Escherichia coli (BDHA-LDH) co-expressing lactate dehydrogenase (LDH) for intracellular regeneration of NAD+ catalyzed the regio- and enantioselective oxidation of (±)-1,2-dihydroxy-1,2,3,4- tetrahydronaphthalene to produce the corresponding (R)-α-hydroxy ketone in >99% ee and (S,S)-cyclic diol in 96% ee at 49% conversion. Preparative biotransformations were also demonstrated. Thus, a novel and useful method for the one-pot synthesis of both vicinal diols and α-hydroxy ketones in high ee was developed via high Copyright
- Zhang, Jiandong,Xu, Tingting,Li, Zhi
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supporting information
p. 3147 - 3153
(2013/12/04)
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- Hyperaromatic stabilization of arenium ions: Acid-catalyzed dehydration of 2-substituted 1,2-dihydro-1-naphthols
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Rate constants for acid-catalyzed dehydration of cis-2-substituted 1,2-dihydro-naphthols are well correlated by the Taft relationship log k = -0.49 - 8.8σI, with minor negative deviations for OH and OMe. By contrast the trans substituents show a poor correlation with σI and in most cases react more slowly than their cis isomers. The behavior is consistent with rate-determining formation of a 2-substituted carbocation (naphthalenium ion) intermediate that for cis reactants possesses a 2-C-H bond suitably oriented for hyperconjugation with the charge center. For the trans isomers the 2-substituent itself is oriented for hyperconjugation in the initially formed conformation of the cation. It is argued that k cis/ktrans rate ratios for substituents (Me, 8.4; Bu t, 12.7; Ph, 3.8; NH3+, 160; OH, 440) reflect their hyperconjugating ability relative to hydrogen. Faster reactions of trans isomers are observed for substitutents known (RS, N3) or suspected (EtSO, EtSO2) of stabilizing the cation by a π or σ neighboring group effect. The good Taft correlation is taken to indicate that cis substuents are reacting normally, differentiated only by their inductive effects. The slower reactions of the trans isomers are the judged to be "abnormal". This is confirmed by comparing effects of cis and trans β-OH substituents on the reactivities of dihydro phenols, naphthols, and phenanthrols. Whereas kH/kOH for cis substituents varies by less than 8-fold and is consistent with the influence of an inductive effect of the OH group (kH/kOH ≈ 2000), kH/k OH for the trans substituents varies by 3 orders of magnitude, reflecting the additional influence of the lesser hyperconjugating ability of a C-OH bond compared to a C-H bond. The magnitude and variation of this difference is consistent with C-H hyperconjugation conferring aromatic character on the arenium ions
- Kudavalli, Jaya Satyanarayana,Coyne, Dara,O'Ferrall, Rory A. More
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supporting information; scheme or table
p. 563 - 572
(2012/03/26)
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- Synthesis and reaction of phthaloyl peroxide derivatives, potential organocatalysts for the stereospecific dihydroxylation of alkenes
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To improve the synthesis and reactivity of phthaloyl peroxide derivatives a method has been developed using sodium percarbonate and phthaloyl chlorides. The reactions of the new phthaloyl peroxide derivatives with trans-stillbene as well as the improved reactivity of 3,4-dichlorophthaloyl peroxide with a variety of alkenes are reported.
- Yuan, Changxia,Axelrod, Abram,Varela, Michael,Danysh, Laura,Siegel, Dionicio
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supporting information; experimental part
p. 2540 - 2542
(2011/06/21)
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- The first total synthesis of racemic 3,4-dihydroxy-2-(3-methylbut-2-enyl)- 3,4-dihydronaphthalen-1(2 H)-one
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Racemic 3,4-dihydroxy-2-(3-methylbut-2-enyl)-3,4-dihydronaphthalen-1(2H)- one is synthesized for the first time, in seven steps, starting from commercially available -tetralone. The key steps in this process are dihydroxylation using osmium tetroxide, benzylic oxidation mediated by sodium chlorite-tert-butyl hydroperoxide, and prenylation. Georg Thieme Verlag Stuttgart New York.
- Suresh, Vangaru,Selvam, Jondass Jon Paul,Rajesh, Karuturi,Shekhar, Vanam,Babu, Dokuburra Chanti,Venkateswarlu, Yenamandra
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experimental part
p. 1763 - 1765
(2010/08/03)
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- Palladium-catalyzed direct oxidation of alkenes with molecular oxygen: General and practical methods for the preparation of 1, 2-diols, aldehydes, and ketones
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(Figure Presented) 1, 2-Diols, aldehydes, and ketones are important intermediates in chemical synthesis, and alkenes are possible precursors for 1, 2-diols, aldehydes, and ketones. Herein, novel and environmentally benign methods for palladium-catalyzed dihydroxylation and oxidative cleavage of olefins with oxygen as sole oxidant are presented. The cleavage reactions were performed with acid as additive in aqueous solution, whereas 1, 2-diols were formed in the presence of base. A broad substrate scope has been demonstrated allowing monosubstituted aromatic and aliphatic terminal alkenes, 1, 2-disubstituted, and 1, 1-disubstituted olefins. The cleavage reactions of dioxo-PdII complexes implicate 1, 2-diol might act as a key intermediate of olefin cleavage.
- Wang, Azhong,Jiang, Huanfeng
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supporting information; experimental part
p. 2321 - 2326
(2010/07/04)
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- Studies of the deracemization of (±)-2-hydroxy-1-tetralone by trichosporon cutaneum
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The diastereo- and enantioselective bioreduction of (±)-2-hydroxy-1- tetralone (6) to the corresponding enantiopure (1S,2R)-cis-1,2-dihydroxy-1,2,3, 4-tetrahydronaphthalene (1) (83% isolated yield, >99% ee), mediated by resting cells of the yeast Trichosporon cutaneum CCT 1903 through dynamic kinetic resolution is reported. Deracemization of (±)-6 was observed in kinetic studies on the biotransformation of the enantiomers (R)-6 and (S)-6.
- Lunardi, Ines,Cazetta, Tarcila,Conceicao, Gelson J. A.,Moran, Paulo J. S.,Rodrigues, J. Augusto R.
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p. 925 - 932
(2008/03/27)
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- NaIO4/LiBr-mediated diastereoselective dihydroxylation of olefins: A catalytic approach to the prevost-woodward reaction
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(Chemical Equation Presented) LiBr catalyzes efficiently the dihydroxylation of alkenes to afford syn and anti diols with excellent diastereoselectivity depending upon the use of NaIO4 (30 mol %) or PhI(OAc)2 (1 equiv), respectively, as the oxidants. The oxidation of non-benzylic halides has been achieved for the first time to afford the corresponding diols in excellent yields.
- Emmanuvel, Lourdusamy,Ali Shaikh, Tanveer Mahammad,Sudalai, Arumugam
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p. 5071 - 5074
(2007/10/03)
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- Cyclodextrins containing an acetone bridge. Synthesis and study as epoxidation catalysts
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Three cyclodextrine derivatives (6A,6 D-di-O-(prop-2-one-1,3-dienyl)-α-cyclodextrin (1), 6-O-(prop-2-one-1-yl)-α-cyclodextrin (2) and 6A,6 D-di-O-(prop-2-one-l, 3-dienyl)-β-cyclodextrin (3)) were synthesised and investigated as epoxidation catalysts. The three compounds were synthesised from the corresponding perbenzylated cyclodextrins which were mono- or didebenzylated in the 6-position using Sinay's method. Reaction with NaH and methallyl chloride in the case of 2, or methallyl dichloride in the case of 1 and 3, followed by dihydroxylation, periodate cleavage and protection group removal gave the target compounds. All three compounds catalysed, in the presence of oxone, the epoxidation of a series of alkenes. Epoxidation was compared to the reaction catalysed by simple ketones and inhibition was studied.
- Rousseau, Cyril,Christensen, Brian,Petersen, Torben Ellebaek,Bols, Mikael
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p. 3476 - 3482
(2007/10/03)
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- Ruthenium nanoparticles supported on hydroxyapatite as an efficient and recyclable catalyst for cis-dihydroxylation and oxidative cleavage of alkenes
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Impregnation of hydroxyapatite with colloidal ruthenium results in the formation of a catalyst that effects cis-dihydroxylation and oxidative cleavage of alkenes to their respective cis-1,2-diols and carbonyl products in good to excellent yields (see scheme). The supported ruthenium catalyst can be easily recycled and reused for consecutive reaction runs without significant deterioration of the catalytic activities. R1, R2 = H, alkyl, aryl.
- Ho, Chi-Ming,Yu, Wing-Yiu,Che, Chi-Ming
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p. 3303 - 3307
(2007/10/03)
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- Microbiological transformations 32: Use of epoxide hydrolase mediated biohydrolysis as a way to enantiopure epoxides and vicinal diols: Application to substituted styrene oxide derivatives
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The biohydrolyses of various substituted styrene oxide derivatives using the fungi Aspergillus niger or Beauveria sulferescens are described. The results obtained show that this methodology allows the preparation of enantiomerically enriched epoxides and diols via enantioselective and regioselective hydration. The comparative study of the results obtained suggests that these hydrolyses operate following different mechanisms and a model of the corresponding active sites is proposed.
- Pedragosa-Moreau,Archelas,Furstoss
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p. 4593 - 4606
(2007/10/03)
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- Photolysis of cis-1,2-Dihydroxyindane Carbonate and cis-1,2-Dihydroxy-1,2,3,4-tetrahydronaphthalene Carbonate
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Cyclic carbonate esters 2 and 3 were prepared and the photochemistry studied.The direct irradiation of these esters produces 1,3-diradicals which undergo either ring closure to form epoxides, H migration to form ketones or Grob type fragmentation processes which lead to products via ring expansion or contraction.
- White, Rick C.,Drew, Phil,Moorman, Richard
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p. 1781 - 1783
(2007/10/02)
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- EFFECT OF THE 9-METHYL SUBSTITUENT ON THE CHEMICAL BEHAVIOUR UNDER ACID CONDITIONS OF THE DIASTEREOISOMERIC 9,10-OXIDES DERIVED FROM trans-1,2,3,4,4a,10a-HEXAHYDROPHENANTHRENE
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Significant differences are present in the chemical behaviour, under acidic ring-opening conditions, between the diastereoisomeric couples of 2-aryl substituted oxiranes 3a and 3e, and 4a and 4e.The results of the acid hydrolysis of the two types of epoxides (3 and 4) have been rationalized through two different mechanisms which cannot easily be reconciled.A substantial structural difference in the two systems is the presence of a tertiary benzylic oxirane carbon in epoxides 3 and of a secondary one in epoxides 4.Therefore, the 9-methyl substituted epoxides 5a and 5e, in which the benzylic oxirane carbon is tertiary, have been prepared and studied.The introduction of the methyl substituent in the 9-position does not modify, in the case of epoxide 5a, the complete anti diastereoselectivity originally observed in the hydrolysis of the unsubstituted epoxide 4a.By way of contrast, in the hydrolysis of epoxide 5e and in the trichloroacetolysis of both epoxides 5a and 5e, a considerable increase in the syn/anti ratio is observed when compared with the data obtained in the corresponding reactions of the non-methyl-substituted epoxides (4a and 4e).Furthermore, in the trichloroacetolysis reactions of both epoxides 5a and 5e, marked amounts of the corresponding non-addition products (ketone and unsaturated alcohol) are revealed.Apart from the increased syn diastereoselectivity in the hydrolysis of epoxide 5e and in the trichloroacetolysis of 5a and 5e, and from the incursion of non-addition products in the trichloroacetolysis of both 5a and 5e, the general trend of the reactions of epoxides 5a and 5e remains substantially unmodified with respect to the one observed with the parent compounds 4a and 4e.The formation of rearrangement products in the reactions of epoxides 5 was rationalized keeping into consideration either the steric or/and the elctronic effect of the 9-methyl substituent.The results obtained indicate that the secondary nature of the benzylic oxirane carbon of epoxides 4a,e is not responsible for the above-mentioned differences in chemical behaviour between epoxides of type 3 and 4.
- Chini, Marco,Crotti, Paolo,Macchia, Franco
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p. 827 - 836
(2007/10/02)
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- Synthesis of the o-Quinones and Dihydro Diols of Polycyclic Aromatic Hydrocarbons from the Corresponding Phenols
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Terminal-ring trans-dihydro diol metabolites have been implicated as the ultimate carcinogenic forms of polycyclic aromatic hydrocarbons.Synthesis of these dihydro diols from the related polycyclic phenols in two steps via oxidation to the corresponding o-quinones with either Fremy's salt or phenylseleninic anhydride followed by stereospecific reduction with lithium aluminum hydride is described.The non-K-region quinones and trans-dihydro diols of naphthalene, anthracene, phenanthrene, benzanthracene, benzopyrene, and 7,12-dimethylbenzanthracene are synthesized via this approach.Although poor yields (1-4percent) were previously reported for the reduction of non-K-region quinones, an improved experimental procedure has been developed which affords the trans-dihydro diols free of the isomeric cis-dihydro diols in generally good yields.Major byproducts are the corresponding hydroquinones, previously undetected, and the related tetrahydro diols.The latter are the major products of reduction of the poorly soluble quinones of benzopyrene and benzanthracene and are shown to arise through further reduction of the dihydro diols.Since the tetrahydro diols are convertible to dihydro diols and the hydroquinones are reoxidizable to quinones, good overall conversions of quinones to dihydro diols are attainable. trans-3,4-Dihydroxy-3,4-dihydro-7,12-dimethylbenzanthracene synthesized in these studies is the most potent tumorigenic hydrocarbon metabolite tested to date.
- Sukumaran, K.B.,Harvey, Ronald G.
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p. 4407 - 4413
(2007/10/02)
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