- Chiral Synthesis of 3-Substituted and 3,3-Disubstituted γ-Butyrolactones by Enantioselective Deprotonation Strategy
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Chiral synthesis of 3-substituted and 3,3-disubstituted γ-butyrolactones was achieved by employing an enantioselctive deprotonation of the corresponding cyclobutanone derivatives with chiral bases as a key reaction.
- Honda, Toshio,Kimura, Nobuaki,Tsubuki, Masayoshi
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- Enantioselective Rh-Catalyzed Anti-Markovnikov Hydroformylation of 1,1-Disubstituted Allylic Alcohols and Amines: An Efficient Route to Chiral Lactones and Lactams
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Rh-catalyzed highly enantioselective anti-Markovnikov hydroformylation of 1,1-disubstituted allylic alcohols and amines has been achieved. By using a chiral hybrid phosphorus ligand, a series of challenging 1,1-disubstituted allylic alcohols and amines we
- You, Cai,Li, Shuailong,Li, Xiuxiu,Lv, Hui,Zhang, Xumu
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- Asymmetric Conjugate Addition of Chiral Secondary Borylalkyl Copper Species
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We report the diastereo- and enantioselective conjugate addition of chiral secondary borylalkyl copper species derived from borylalkenes in situ to α,β-unsaturated diesters. In the presence of a chiral bisphosphine-ligated CuH catalyst, the conjugate addition provides a direct access to enantioenriched alkylboron compounds containing two contiguous carbon stereogenic centers in good yield with high diastereo- and enantioselectivity (up to >98:2 dr, >99:1 er) by assembling readily available starting alkenyl reagents in a single operation without using preformed organometallic reagents or chiral auxiliaries. The resulting products were used in various organic transformations. The utility of the synthetic approach was highlighted by the synthesis of (?)-phaseolinic acid.
- Jang, Won Jun,Woo, Jeongkyu,Yun, Jaesook
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supporting information
p. 4614 - 4618
(2021/01/18)
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- The rationale for stereoinduction in conjugate addition to alkylidenemalonates bearing a menthol-derived chiral auxiliary
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Density-functional theory (DFT) calculations provided a new model to rationalize the stereoselectivity in the asymmetric addition to alkylidenemalonate bearing 8-phenylmenthyl groups as a chiral auxiliary. The diastereoselectivity in the addition reactions of a tetramethyldioxolanyl radical with various alkyl 8-phenylmenthyl benzylidenemalonates strongly supports the proposed model.
- Yamada, Ken-ichi,Fujiwara, Shinichi,Inokuma, Tsubasa,Sugano, Masayuki,Yamaoka, Yousuke,Takasu, Kiyosei
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- Investigation of a New Type I Baeyer–Villiger Monooxygenase from Amycolatopsis thermoflava Revealed High Thermodynamic but Limited Kinetic Stability
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Baeyer–Villiger monooxygenases (BVMOs) are remarkable biocatalysts, but, due to their low stability, their application in industry is hampered. Thus, there is a high demand to expand on the diversity and increase the stability of this class of enzyme. Sta
- Mansouri, Hamid R.,Mihovilovic, Marko D.,Rudroff, Florian
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p. 971 - 977
(2020/01/22)
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- The mutagenesis of a single site for enhancing or reversing the enantio- or regiopreference of cyclohexanone monooxygenases
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The mutagenesis of a "second sphere"switch residue of CHMOAcineto could control its enantio- and regiopreference. Replacing phenylalanine (F) at position 277 of CHMOAcineto into larger tryptophan (W) enabled a significant enhancement of enantio- or regioselectivity toward structurally diverse substrates, moreover, a complete reversal of enantio- or regiopreference was realized by mutating F277 into a range of smaller amino acids (A/C/D/E/G/H/I/K/L/M/N/P/Q/R/S/T/V).
- Hu, Yujing,Xu, Weihua,Hui, Chenggong,Xu, Jian,Huang, Meilan,Lin, Xianfu,Wu, Qi
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supporting information
p. 9356 - 9359
(2020/11/02)
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- Phosphothreonine (pThr)-Based Multifunctional Peptide Catalysis for Asymmetric Baeyer-Villiger Oxidations of Cyclobutanones
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Biologically inspired phosphothreonine (pThr)-embedded peptides that function as chiral Br?nsted acid catalysts for enantioselective Baeyer-Villiger oxidations (BV) of cyclobutanones with aqueous H2O2 are reported herein. Complementa
- Featherston, Aaron L.,Shugrue, Christopher R.,Mercado, Brandon Q.,Miller, Scott J.
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p. 242 - 252
(2019/01/04)
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- Catalytic Asymmetric Conjugate Addition of a Borylalkyl Copper Complex for Chiral Organoboronate Synthesis
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We report the catalytic enantioselective conjugate addition of a borylalkyl copper nucleophile generated in situ from a 1,1-diborylmethane derivative to α,β-unsaturated diesters. In the presence of a chiral N-heterocyclic carbene (NHC)–copper catalyst, this method facilitated the enantioselective incorporation of a CH2Bpin moiety at the β-position of the diesters to yield β-chiral alkyl boronates in up to 86 % yield with high enantioselectivity. The alkylboron moiety in the resulting chiral diester products was converted into various functional groups by organic transformation of the C?B bond.
- Jang, Won Jun,Yun, Jaesook
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supporting information
p. 18131 - 18135
(2019/11/13)
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- Heterogeneous Chiral Diene-Rh Complexes for Asymmetric Arylation of α,β-Unsaturated Carbonyl Compounds, Nitroalkenes, and Imines
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A chiral diene ligand with tertiary alkyl amine-derived secondary amide moiety was immobilized on cross-linked polystyrene (PS) by radical polymerization, which was combined with Rh to form heterogeneous chiral Rh complexes (PS-diene Rh?Cl). PS-diene Rh?Cl catalyzed asymmetric arylation reactions of α,β-unsaturated carbonyl compounds (ketones, esters, and amides), nitroalkenes, and imines afforded the desired products in high yields with excellent enantioselectivities. PS-diene Rh?Cl is stable in air, can be stored for several months, and can be reused more than 10 times without any reduction of either yield or enantioselectivity. We also developed a method of activation of PS-diene Rh?Cl to generate more active species. (Figure presented.).
- Kuremoto, Tatsuya,Yasukawa, Tomohiro,Kobayashi, Shū
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supporting information
p. 3698 - 3703
(2019/07/12)
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- A diastereomeric pair of sulfoxide-containing chiral MOP-type ligands: Preparation and application to rhodium-catalyzed asymmetric 1,4-addition reactions
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(R,SS)-Sulfoxide-MOP (L2) and (R,RS)-sulfoxide-MOP (L3) were developed as a diastereomeric pair of sulfoxide-containing chiral MOP-type ligands. These two ligands also represent the first monosulfoxide analogues of BINAP. The chiral ligand L2 was successfully applied to the highly enantioselective rhodium-catalyzed 1,4-addition between α,β-unsaturated ketones or esters and arylboronic acids, and exhibited a broad substrate scope when the reaction was performed using 1.5 mol% Rh in cyclohexane/H2O (10:1) at 40 °C under mild basic conditions.
- Hoshi, Takashi,Fujita, Masataka,Matsushima, Shouta,Hagiwara, Hisahiro,Suzuki, Toshio
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supporting information
p. 800 - 802
(2018/06/12)
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- Manipulating the stereoselectivity of the thermostable Baeyer-Villiger monooxygenase TmCHMO by directed evolution
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Baeyer-Villiger monooxygenases (BVMOs) and evolved mutants have been shown to be excellent biocatalysts in many stereoselective Baeyer-Villiger transformations, but industrial applications are rare which is partly due to the insufficient thermostability o
- Li, Guangyue,Fürst, Maximilian J. L. J.,Mansouri, Hamid Reza,Ressmann, Anna K.,Ilie, Adriana,Rudroff, Florian,Mihovilovic, Marko D.,Fraaije, Marco W.,Reetz, Manfred T.
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p. 9824 - 9829
(2017/12/08)
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- Catalytic, Enantioselective β-Protonation through a Cooperative Activation Strategy
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The NHC-catalyzed transformation of unsaturated aldehydes into saturated esters through an organocatalytic homoenolate process has been thoroughly studied. Leveraging a unique “Umpolung”-mediated β-protonation, this process has evolved from a test bed for homoenolate reactivity to a broader platform for asymmetric catalysis. Inspired by our success in using the β-protonation process to generate enals from ynals with good E/Z selectivity, our early studies found that an asymmetric variation of this reaction was not only feasible, but also adaptable to a kinetic resolution of secondary alcohols through NHC-catalyzed acylation. In-depth analysis of this process determined that careful catalyst and solvent pairing is critical for optimal yield and selectivity; proper choice of nonpolar solvent provided improved yield through suppression of an oxidative side reaction, while employment of a cooperative catalytic approach through inclusion of a hydrogen bond donor cocatalyst significantly improved enantioselectivity.
- Wang, Michael H.,Barsoum, David,Schwamb, C. Benjamin,Cohen, Daniel T.,Goess, Brian C.,Riedrich, Matthias,Chan, Audrey,Maki, Brooks E.,Mishra, Rama K.,Scheidt, Karl A.
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p. 4689 - 4702
(2017/05/12)
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- Direct Organocatalytic Multicomponent Synthesis of Enantiopure γ-Butyrolactones via Tandem Knoevenagel-Michael-Lactonization Sequence
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An expedient and straightforward protocol is developed for the synthesis of highly enantiopure synthesis of γ-butyrolactones. For the first time, one pot enantioselective organocatalytic multicomponent reaction (OMCR) is explored to construct functionalized butyrolactones without the use of pre-functionalized substrates and expensive transition metals. The protocol is proved to be reproducible on a gram scale. Density functional theory (DFT) calculations strongly support the mechanism and were in close agreement with the observed high stereoselectivity. (Figure presented.).
- Khopade, Tushar M.,Sonawane, Amol D.,Arora, Jyotsna S.,Bhat, Ramakrishna G.
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supporting information
p. 3905 - 3910
(2017/10/07)
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- Chemo-enzymatic Baeyer-Villiger oxidation of 4-methylcyclohexanone via kinetic resolution of racemic carboxylic acids: Direct access to enantioenriched lactone
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A new method for the asymmetric chemo-enzymatic Baeyer-Villiger oxidation of prochiral 4-methylcyclohexanone to (R)-4-methylcaprolactone in the presence of (±)-4-methyloctanoic acid, Candida Antarctica lipase B and 30% aq. H2O2 has been developed. A mechanism for the asymmetric induction based on kinetic resolution of racemic carboxylic acids is proposed.
- Drozdz, Agnieszka,Chrobok, Anna
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supporting information
p. 1230 - 1233
(2016/01/15)
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- Self-assembled ion-pair organocatalysis - Asymmetric Baeyer-Villiger oxidation mediated by flavinium-cinchona alkaloid dimer
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An ion-pair catalyst generated by assembly of a chiral flavinium and a cinchona alkaloid dimer for use in asymmetric Baeyer-Villiger oxidation is presented. Ion-pair formation is essential for enhancing the catalytic activity and stereoselectivity. The catalyst is applicable to structurally diverse 3-substituted cyclobutanones, providing good to excellent enantioselectivities (up to 98: 2 e.r.). This study provides the first example of self-assembly of a flavin derivative and a base to form a chiral reaction site that enables a highly stereoselective reaction to occur.
- Poudel, Pramod Prasad,Arimitsu, Kenji,Yamamoto, Kana
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supporting information
p. 4163 - 4166
(2016/03/19)
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- Baeyer–Villiger monooxygenase-catalyzed desymmetrizations of cyclobutanones. Application to the synthesis of valuable spirolactones
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A series of γ-butyrolactone derivatives, including some spiranic ones, was obtained through desymmetrization of the corresponding prochiral 3-substituted cyclobutanones via Baeyer–Villiger monooxygenase (BVMO)-catalyzed oxidation. After reaction optimization using several commercial enzymes, both antipodes of various lactones were synthesized in most cases with >90% conversion and >80% enantiomeric excess under mild reaction conditions. In some cases alcohol formation was also observed (up to 40% conversion) as an undesired side reaction due to the presence of alcohol dehydrogenases in these preparations. Selected transformations were achieved on a 100 mg scale showing the possibilities of these oxidative biocatalysts as a new source of highly interesting compounds.
- Rodríguez-Mata, María,Lavandera, Iván,Gotor-Fernández, Vicente,Gotor, Vicente,García-Cerrada, Susana,Mendiola, Javier,de Frutos, óscar,Collado, Iván
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supporting information
p. 7268 - 7275
(2016/10/26)
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- Enantioselective β-Protonation by a Cooperative Catalysis Strategy
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An enantioselective N-heterocyclic carbene (NHC)-catalyzed β-protonation through the orchestration of three distinct organocatalysts has been developed. This cooperative catalyst system enhances both yield and selectivity, compared to only the NHC-catalyz
- Wang, Michael H.,Cohen, Daniel T.,Schwamb, C. Benjamin,Mishra, Rama K.,Scheidt, Karl A.
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supporting information
p. 5891 - 5894
(2015/05/27)
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- Chiral Metal Nanoparticle Systems as Heterogeneous Catalysts beyond Homogeneous Metal Complex Catalysts for Asymmetric Addition of Arylboronic Acids to α,β-Unsaturated Carbonyl Compounds
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We describe the use of chiral metal nanoparticle systems, as novel heterogeneous chiral catalysts for the asymmetric 1,4-addition of arylboronic acids to α,β-unsaturated carbonyl compounds, as representative C-C bond-forming reactions. The reactions proceeded smoothly to afford the corresponding β-arylated products in high to excellent yields and outstanding enantioselectivities with wide substrate scope. Remarkably, the nanoparticle catalysts showed performance in terms of yield, enantioselectivity, and catalytic turnover that was superior to that of the corresponding homogeneous metal complexes. The catalyst can be successfully recovered and reused in a gram-scale synthesis with low catalyst loading without significant loss of activity. The nature of the active species was investigated, and we found that characteristic features of the nanoparticle system were totally different from those of the metal complex system. (Chemical Equation Presented).
- Yasukawa, Tomohiro,Suzuki, Aya,Miyamura, Hiroyuki,Nishino, Kohei,Kobayashi, Shu
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supporting information
p. 6616 - 6623
(2015/06/08)
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- Stable chiral complexes of ionic liquids with Aluminium and biaryl ligands as efficient catalysts for the synthesis of chiral lactones
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A new catalytic system for the asymmetric Baeyer-?Villiger oxidation of monosubstituted prochiral cyclobutanones to γ-butyrolactones with high yields (40-99%) and enantioselectivities (45-87%) is described. Aluminium complexes with biaryl ligands and ioni
- Drozdz, Agnieszka,Foreiter, Magdalena B.,Chrobok, Anna
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p. 559 - 563
(2014/03/21)
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- Type II flavin-containing monooxygenases: A new class of biocatalysts that harbors baeyer-villiger monooxygenases with a relaxed coenzyme specificity
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Within a newly identified set of flavin-containing monooxygenases (FMOs) from Rhodococcus jostii RHA1, we have identified three monooxygenases (FMO-E, FMO-F, and FMO-G) that are effective in catalyzing Baeyer-Villiger oxidations. These type II FMOs display relaxed coenzyme specificity by accepting both NADPH (reduced form of nicotinamide adenine dinucleotide phosphate) and NADH (reduced form of nicotinamide adenine dinucleotide), as a coenzyme, which is a novel and attractive feature among biocatalysts capable of conducting Baeyer-Villiger oxidations. We purified FMO-E and determined that the Michaelis constants for both coenzymes were in the micromolar range, whereas the activity was highest for NADH. By using the stopped-flow technique, formation of a peroxyflavin-enzyme intermediate was observed, which indicated that type II FMOs follow a catalytic mechanism similar to that of other class B flavoprotein monooxygenases. A set of cyclobutanones and cyclohexanones were used to probe the regio- and enantioselectivity of all three recombinant monooxygenases. The biocatalysts readily accepted small cyclic ketones, which enabled the conversion of previously poorly accepted substrates by other monooxygenases (especially norcamphor), and exhibited excellent and unique regio- and enantioselectivities. Sequence analysis revealed that type II FMOs that act as Baeyer-Villiger monooxygenases contain a unique N-terminal domain. Sequence conservation in this protein domain can be used to identify new NADH-dependent Baeyer-Villiger monooxygenases, which would facilitate future biocatalyst discovery efforts. New kid on the block: Members of a newly recognized group of sequence-related flavin-containing monooxygenases can perform Baeyer-Villiger oxidations. Their coenzyme indifference and unique specificity make them attractive biocatalysts.
- Riebel, Anette,Fink, Michael J.,Mihovilovic, Marko D.,Fraaije, Marco W.
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p. 1112 - 1117
(2014/05/06)
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- The steroid monooxygenase from Rhodococcus rhodochrous; A versatile biocatalyst
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The substrate scope of a steroid monooxygenase (STMO) from Rhodococcus rhodochrous DSM 43269 was investigated for a large range of different ketone substrates. These studies revealed that this enzyme not only oxygenates steroids, but also ketone moieties of a series of other open-chain ketones, such as cyclohexyl methyl ketone, cyclopentyl methyl ketone, and 3-acetylindole. Furthermore, the STMO catalyzed the oxygenation of cyclobutanone derivatives. Comparative biotransformations with recombinant Escherichia coli resting cells harboring the STMO, the cycloalkanone monooxygenase (CAMO) from Cylindrocarpon radicicola or the cyclohexanone monooxygenase (CHMO) from Acinetobacter calcoaceticus revealed that the STMO is enantiodivergent compared to the CHMO-type. Moreover, the STMO resulted in a higher enantiomeric excess of the product lactones compared to the known BVMOs of the same enantiopreference, such as cyclopentanone monooxygenases.
- Leipold, Friedemann,Rudroff, Florian,Mihovilovic, Marko D.,Bornscheuer, Uwe T.
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p. 1620 - 1624
(2014/01/06)
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- Efficient asymmetric Baeyer-Villiger oxidation of prochiral cyclobutanones using new polymer-supported and unsupported chiral co(salen) complexes
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Two heterogeneous catalysts 4 and 5 and three homogenous complexes 1-3 were prepared and used for enantioselective Baeyer-Villiger (B-V) oxidation of prochiral cyclobutanones. Among the prepared catalysts, the supported ones showed better enantioselectivi
- Sandaroos, Reza,Goldani, Mohammad Taghi,Damavandi, Saman,Mohammadi, Ali
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p. 871 - 876,6
(2020/09/09)
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- Enantioselective baeyer-villiger oxidation: Desymmetrization of meso cyclic ketones and kinetic resolution of racemic 2-arylcyclohexanones
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Catalytic enantioselective Baeyer-Villiger (BV) oxidations of racemic and meso cyclic ketones were achieved in the presence of chiral N,N'-dioxide-Sc III complex catalysts. The BV oxidations of prochiral cyclohexanones and cyclobutanones afforded series of optically active μ- and γ-lactones, respectively, in up to 99% yield and 95% ee. Meanwhile, the kinetic resolution of racemic 2-arylcyclohexanones was also realized via an abnormal BV oxidation. Enantioenriched 3-aryloxepan-2-ones, whose formation is counter to the migratory aptitude, were obtained preferentially. Both the lactones and the unreacted ketones were obtained with high ee values.
- Zhou, Lin,Liu, Xiaohua,Ji, Jie,Zhang, Yuheng,Hu, Xiaolei,Lin, Lili,Feng, Xiaoming
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p. 17023 - 17026,4
(2012/12/12)
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- Enantioselective baeyer-villiger oxidation: Desymmetrization of meso cyclic ketones and kinetic resolution of racemic 2-arylcyclohexanones
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Catalytic enantioselective Baeyer-Villiger (BV) oxidations of racemic and meso cyclic ketones were achieved in the presence of chiral N,N'-dioxide-Sc III complex catalysts. The BV oxidations of prochiral cyclohexanones and cyclobutanones afforded series of optically active μ- and γ-lactones, respectively, in up to 99% yield and 95% ee. Meanwhile, the kinetic resolution of racemic 2-arylcyclohexanones was also realized via an abnormal BV oxidation. Enantioenriched 3-aryloxepan-2-ones, whose formation is counter to the migratory aptitude, were obtained preferentially. Both the lactones and the unreacted ketones were obtained with high ee values.
- Zhou, Lin,Liu, Xiaohua,Ji, Jie,Zhang, Yuheng,Hu, Xiaolei,Lin, Lili,Feng, Xiaoming
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p. 17023 - 17026
(2013/01/15)
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- Iridium-catalyzed enantioselective allylic alkylation of methyl 2-(4-nitrophenylsulfonyl)acetate and subsequent transformations
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Highly enantioselective allylic alkylation reactions of methyl 2-(4-nitrophenylsulfonyl)acetate were carried out in the presence of an iridium catalytic system. The subsequent transformations of the products including reductive desulfonylation and modifie
- Xu, Qing-Long,Dai, Li-Xin,You, Shu-Li
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supporting information
p. 2275 - 2282
(2012/11/07)
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- Chiral hetero- and carbocyclic compounds from the asymmetric hydrogenation of cyclic alkenes
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Several types of chiral hetero- and carbocyclic compounds have been synthesized by using the asymmetric hydrogenation of cyclic alkenes. N,P-Ligated iridium catalysts reduced six-membered cyclic alkenes with various substituents and heterofunctionality in good to excellent enantioselectivity, whereas the reduction of five-membered cyclic alkenes was generally less selective, giving modest enantiomeric excesses. The stereoselectivity of the hydrogenation depended more strongly on the substrate structure for the five- rather than the six-membered cyclic alkenes. The major enantiomer formed in the reduction of six-membered alkenes could be predicted from a selectivity model and isomeric alkenes had complementary enantioselectivity, giving opposite optical isomers upon hydrogenation. The utility of the reaction was demonstrated by using it as a key step in the preparation of chiral 1,3-cis-cyclohexane carboxylates. Copyright
- Verendel, J. Johan,Li, Jia-Qi,Quan, Xu,Peters, Byron,Zhou, Taigang,Gautun, Odd R.,Govender, Thavendran,Andersson, Pher G.
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supporting information; experimental part
p. 6507 - 6513
(2012/06/29)
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- Exo-selective asymmetric inverse-electron demand hetero-diels-alder reaction catalyzed by Cu(II)-hydroxy oxazoline ligands
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Cu(II) complexes of hydroxy oxazolines derived from (+)-(S)-ketopinic acid catalyze the asymmetric hetero-Diels-Alder cycloaddition of enol ethers and ,-unsaturated -keto esters. The reaction takes place with unprecedented exo selectivity providing 2,4-trans-disubstituted chiral 2,3-dihydropyrans with up to 88% ee. Georg Thieme Verlag Stuttgart ? New York.
- Barba, Andrea,Barroso, Santiago,Blay, Gonzalo,Cardona, Luz,Melegari, Martina,Pedro, José R.
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scheme or table
p. 1592 - 1596
(2011/08/03)
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- (R)-3,5-diCF3-SYNPHOS and (R)- p -CF3-SYNPHOS, electron-poor diphosphines for efficient room temperature Rh-catalyzed asymmetric conjugate addition of arylboronic acids
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Two new atropisomeric electron-poor chiral diphosphine ligand analogues of SYNPHOS were prepared, and their electronic properties are described. These two ligands afforded high performance for the Rh-catalyzed asymmetric 1,4-addition of arylboronic acids to α,β-unsaturated carbonyl compounds at room temperature.
- Berhal, Farouk,Esseiva, Olivier,Martin, Charles-Henri,Tone, Hitoshi,Genet, Jean-Pierre,Ayad, Tahar,Ratovelomanana-Vidal, Virginie
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supporting information; experimental part
p. 2806 - 2809
(2011/07/09)
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- Rh-catalyzed asymmetric 1,4-addition of arylboronic acids to α,β-unsaturated ketones with DIFLUORPHOS and SYNPHOS analogues
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Applications of electron-deficient DIFLUORPHOS and SYNPHOS analogues in the rhodium-catalyzed asymmetric conjugate addition of boronic acids to α,β-unsaturated ketones afford the 1,4-addition adducts in yields up to 92% and with 99% ee. Particularly, a Rh-catalyzed asymmetric 1,4-addition of arylboronic acids to nonsubstituted maleimide substrates using the (R)-3,5-diCF3-SYNPHOS ligand is also reported. This protocol provides access to various enantioenriched 3-substituted succinimide units of biological interest, in high yields and good to excellent ee up to 93%, which could be upgraded up to 99% ee, after a single crystallization.
- Berhal, Farouk,Wu, Zi,Genet, Jean-Pierre,Ayad, Tahar,Ratovelomanana-Vidal, Virginie
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scheme or table
p. 6320 - 6326
(2011/10/05)
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- [5]Ferrocenophanene-Phosphane Ligands for Enantioselective Rh-Catalyzed Conjugate Additions
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Ferrocenophanene-phosphane ligands with bridged cyclopentadienyl rings have been synthesized and characterized by spectroscopic methods. Rhodium complexes of these ligands can catalyze the Michael addition of phenylboronic acid to cyclic enones and lacton
- Csizmadiova, Jana,Meciarova, Maria,Rakovsky, Erik,Horvath, Branislav,sebesta, Radovan
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experimental part
p. 6110 - 6116
(2011/12/03)
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- Palladium-catalyzed, asymmetric Baeyer-Villiger oxidation of prochiral cyclobutanones with PHOX ligands
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Described in this report is a general method for the conversion of prochiral 3-substituted cyclobutanones to enantioenriched γ-lactones through a palladium-catalyzed Baeyer-Villiger oxidation using phosphinooxazoline ligands in up to 99% yield and 81% ee. Lactones of enantiopurity ≥93% could be obtained through a single recrystallization step. Importantly, 3,3-disubtituted cyclobutanones produced enantioenriched lactones containing a β-quaternary center.
- Petersen, Kimberly S.,Stoltz, Brian M.
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experimental part
p. 4352 - 4357
(2011/07/29)
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- Mechanistic investigation of chiral phosphoric acid catalyzed asymmetric baeyer-villiger reaction of 3-substituted cyclobutanones with H 2O2 as the oxidant
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The mechanism of the chiral phosphoric acid catalyzed Baeyer-Villiger (B-V) reaction of cyclobutanones with hydrogen peroxide was investigated by using a combination of experimental and theoretical methods. Of the two pathways that have been proposed for the present reaction, the pathway involving a peroxyphosphate intermediate is not viable. The reaction progress kinetic analysis indicates that the reaction is partially inhibited by the y-lactone product. Initial rate measurements suggest that the reaction follows Michaelis-Menten-type kinetics consistent with a bifunctional mechanism in which the catalyst is actively involved in both carbonyl addition and the subsequent rearrangement steps through hydrogen-bonding interactions with the reactants or the intermediate. High-level quantum chemical calculations strongly support a two-step concerted mechanism in which the phosphoric acid activates the reactants or the intermediate in a synergistic manner through partial proton transfer. The catalyst simultaneously acts as a general acid, by increasing the electrophilicity of the carbonyl carbon, increases the nucleophilicity of hydrogen peroxide as a Lewis base in the addition step, and facilitates the dissociation of the OH group from the Criegee intermediate in the rearrangement step. The overall reaction is highly exothermic, and the rearrangement of the Criegee intermediate is the rate-determining step. The observed reactivity of this catalytic B-V reaction also results, in part, from the ring strain in cyclobutanones. The sense of chiral induction is rationalized by the analysis of the relative energies of the competing diastereomeric transition states, in which the steric repulsion between the 3-substituent of the cyclobutanone and the 3- and 3'-substituents of the catalyst, as well as the entropy and solvent effects, are found to be critically important.
- Xu, Senmiao,Wang, Zheng,Li, Yuxue,Zhang, Xumu,Wang, Haiming,Ding, Kuiling
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experimental part
p. 3021 - 3035
(2010/08/06)
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- Charge-transfer effect on chiral phosphoric acid catalyzed asymmetric Baeyer-Villiger oxidation of 3-substituted cyclobutanones using 30% aqueous H2O2 as the oxidant
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The intermolecular charge-transfer effect has been employed for the first time as a modulating approach to affect the enantioselectivity in asymmetric catalysis by taking the chiral phosphoric acid catalyzed asymmetric Baeyer-Villiger oxidation of 3-aryl
- Xu, Senmiao,Wang, Zheng,Zhang, Xumu,Ding, Kuiling
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experimental part
p. 1731 - 1735
(2011/07/08)
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- Chemoenzymatic synthesis and application of bicyclo [2.2.2] octadiene ligands: Increased efficiency in rhodium-catalyzed asymmetric conjugate additions by electronic tuning
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(Figure Presented) On your bi(cycle)kel A series of 1,4dimethyl bicyclic [2.2.2] diene ligands with tunable substitution at the bridge positions was accessed using a lipase resolution and a high yielding six step sequence (see scheme). The bridgehead meth
- Luo, Yunfei,Cornell, Andrew J.
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supporting information; experimental part
p. 2750 - 2754
(2010/07/03)
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- Catalytic asymmetric Baeyer-Villiger oxidation in water by using Pt IIcatalysts and hydrogen peroxide: Supramolecular control of enantioselectivity
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The enantioselective BaeyerVilliger oxidation of cyclic ketones is a challenging reaction, especially when using environmentally friendly oxidants. The reaction was carried out in water by using soft Lewis acid PtII complexes that have chiral diphosphines as well as monophosphines. Addition of a surfactant is crucial, which leads to the formation of micelles that act as nanoreactors in which the substrate and catalyst encounter each other in an ordered medium that in several cases positively influences both the conversion and the selectivity of the reactions. This is due to the combination of the hydrophobic effect (which confines the components of the reaction in the micelles), together with supramolecular interactions between the partners within the ordered palisade provided by the alkyl chains of the surfactant. For the oxidation of wieso-cyclobutanones, addition of surfactant allowed the reaction to proceed in high yields and the enantiometic excess (ee; 56%) was higher than in organic solvents. Subsequent extension to meso-cyclohexanones resulted in a general decrease in yields but an enhancement of enantioselectivity (ee up to 92%) moving from organic to water-surfactant media, regardless of the substrate or the catalyst employed. Different behaviour was observed with chiral cyclobutanones 7 and 10: with 7 the best catalyst was 1g, whereas with the larger substrate, 10, complexes 1a-b performed better in terms of enantioselectivity. Each combination of substrate, catalyst and surfactant is a new system and supramolecular reciprocal interactions together with the hydrophobic character of the counterparts play crucial roles. The asymmetric Baeyer-Villiger oxidation in water catalyzed by 1a-h in the presence of micelles is a viable reaction that often benefits from the hydrophobic effect, leading to substantial increases in enantioselectivity.
- Cavarzan, Alessandra,Bianchini, Giulio,Sgarbossa, Paolo,Lefort, Laurent,Gladiali, Serafino,Scarso, Alessandro,Strukul, Giorgio
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experimental part
p. 7930 - 7939
(2010/03/31)
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- Asymmetric Baeyer-Villiger oxidation with Co(Salen) and H2O 2 in water: Striking supramolecular micelles effect on catalysis
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A micellar environment enables catalytic, diastereoselective and enantioselective Baeyer-Villiger oxidation of cyclobutanones (ee up to 90%) with H2O2 as oxidant using Co(Salen) catalyst 1, while the same catalytic system is inactive in organic solvents. The Royal Society of Chemistry 2009.
- Bianchini, Giulio,Cavarzan, Alessandra,Scarso, Alessandro,Strukul, Giorgio
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experimental part
p. 1517 - 1520
(2010/06/13)
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- C1-symmetric monosubstituted chiral diene ligands in asymmetric rhodium-catalyzed 1,4-addition reactions
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One trumps two: Monosubstituted chiral bicyclo[2.2.2]octadiene ligands, derived from carvone, form complexes with rhodium to catalyze the asymmetric addition of boronic acid substrates to α,β-unsaturated ketones (see scheme). The 1,4-adducts are produced
- Gendrineau, Thomas,Chuzel, Olivier,Eijsberg, Hendrik,Genet, Jean-Pierre,Darses, Sylvain
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experimental part
p. 7669 - 7672
(2009/04/10)
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- Enantioselective baeyer-villiger oxidation catalyzed by palladium(II) complexes with chiral P,N-ligands
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(Chemical Equation Presented) Asymmetric Baeyer-Villiger reaction of symmetrical cyclobutanones 1a-j with urea-hydrogen peroxide (UHP) can be catalyzed by a complex of Pd(II) and the new terpene-derived P,N-ligand 7. The resulting lactones 2a-j were obtained in high yields and with good enantioselectivity (≤81% ee).
- Malkov, Andrei V.,Friscourt, Frederic,Bell, Mark,Swarbrick, Martin E.,Kocovsky, Pavel
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p. 3996 - 4003
(2008/09/20)
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- Chiral Bronsted acid catalyzed asymmetric Baeyer-Villiger reaction of 3-substituted cyclobutanones by using aqueous H2O2
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(Chemical Equation Presented) A catalytic amount of a chiral Bronsted acid with aqueous H2O2 as the oxidant is sufficient for the enantioselective Baeyer-Villiger oxidation of 3-substituted cyclobutanones to give the corresponding γ-
- Xu, Senmiao,Wang, Zheng,Zhang, Xue,Zhang, Xumu,Ding, Kuiling
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p. 2840 - 2843
(2008/12/23)
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- Self-sufficient Baeyer-Villiger monooxygenases: Effective coenzyme regeneration for biooxygenation by fusion engineering
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(Chemical Presented) Two-in-one biocatalysts were engineered by the covalent fusion of NADPH-dependent Baeyer-Villiger monooxygenases to a phosphite dehydrogenase for coenzyme regeneration (see scheme). Not only the purified fusion proteins, but also whole cells and crude cell extracts containing the enzyme conjugates, could be used to catalyze biotransformations with high efficiency. NADP+=nicotinamide adenine dinucleotide phosphate.
- Torres Pazmino, Daniel E.,Snajdrova, Radka,Baas, Bert-Jan,Ghobrial, Michael,Mihovilovic, Marko D.,Fraaije, Marco W.
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supporting information; scheme or table
p. 2275 - 2278
(2009/02/08)
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- Stereoselective desymmetrizations by recombinant whole cells expressing the Baeyer-Villiger monooxygenase from Xanthobacter sp. ZL5: A new biocatalyst accepting structurally demanding substrates
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In this work the substrate profile and stereoselectivity of engineered whole cells overexpressing the Baeyer-Villiger monooxygenase from Xanthobacter sp. ZL5 with respect to biotransformations of prochiral substrates is characterized. This enzyme catalyzes the desymmetrization of cyclic ketones bearing different chemical features with stereoselectivity similar to that obtained with a related protein from Acinetobacter as a prototype representative of the cyclohexanone monooxygenase enzyme cluster. Moreover, this biocatalyst is able to convert sterically demanding substrates previously not transformed by other enzymes with excellent enantioselectivities. These results expand the repertoire of optically pure lactones accessible by whole-cell biotransformation processes, which are useful intermediates for the synthesis of natural and bioactive products. In addition, we observed a remarkable epoxidation reaction of a non-activated C=C bond catalyzed by this monooxygenase. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Rial, Daniela V.,Bianchi, Dario A.,Kapitanova, Petra,Lengar, Alenka,Van Beilen, Jan B.,Mihovilovic, Marko D.
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scheme or table
p. 1203 - 1213
(2009/04/07)
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- Chemoselective conjugate addition of dimethylzinc-mediated ether and acetal radicals to alkylidenemalonates and asymmetric reactions
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(Chemical Equation Presented) Cyclic and acyclic ether or acetal radicals were generated directly from ethers or acetals by the action of dimethylzinc-air, and their subsequent conjugate addition reaction with alkylidenemalonates afforded the corresponding conjugate adducts in reasonably high yields. The reaction with benzylidenemalonates bearing formyl and imino groups gave chemoselectively the conjugate addition products. The asymmetric reaction of bis(8-phenylmenthyl) benzylidenemalonate proceeded diastereoselectively to provide the adduct with 93:7 dr.
- Yamada, Ken-Ichi,Maekawa, Masaru,Akindele, Tito,Nakano, Mayu,Yamamoto, Yasutomo,Tomioka, Kiyoshi
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supporting information; experimental part
p. 9535 - 9538
(2009/04/07)
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- Enantioselective 1,4-addition of arylboronic acids to α,β-unsaturated carbonyl compounds catalyzed by rhodium(I)-chiral phosphoramidite complexes
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A chiral bidentate phosphoramidite (5a) was synthesized from Shibasaki's linked-(R)-BINOL and P(NMe2)3 as a new ligand for rhodium(I)-catalyzed asymmetric 1,4-addition of arylboronic acids to α,β-unsaturated carbonyl compounds. The effects of 5a and Feringa's monodentate phosphoramidite (4, R1, R2 = Et) on the yields and enantioselectivities were fully investigated. The reaction was significantly accelerated in the presence of a base such as KOH and Et3N, allowing the reaction to be completed at the lower temperatures than 50 °C. The addition to cyclic enones such as 2-cyclopentenone, 2-cyclohexenone and 2-cycloheptenone at 50 °C in the presence of an [Rh(coe)2Cl]2-4 (R1, R2 = Et) complex resulted in enantioselectivities up to 98%, though it was less effective for acyclic enones (0-70% ee). On the other hand, a complex between [Rh(nbd)2]BF4 and 5a completed the addition to cyclic enones within 2 h at room temperature in the presence of Et3N with 86-99% yields and 96-99.8% ee. This catalyst was also effective for acyclic enones, resulting in 62-98% yields and 66-94% ee. The 1,4-additions of arylboronic acids to unsaturated lactones and acyclic esters with rhodium(I)-phosphoramidites complexes were also investigated.
- Kurihara, Kazunori,Sugishita, Noriyuki,Oshita, Kengo,Piao, Dongguo,Yamamoto, Yasunori,Miyaura, Norio
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p. 428 - 435
(2008/02/06)
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- Comparing the stereoselective biooxidation of cyclobutanones by recombinant strains expressing bacterial baeyer - Villiger monooxygenases
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Microbial Baeyer - Villiger oxidation of representative prochiral ketones with a cyclobutanone structural motif was investigated using a collection of eight monooxygenases of different bacterial origin. This platform of enzymes is able to perform stereoselective biotransformations on an array of structurally diverse substrates. With several ketone precursors, biooxidations yielded enantiocomplementary butyrolactones as key intermediates for the synthesis of natural products and bioactive compounds. The microbial Baeyer - Villiger oxidation allows a facile and rapid entry to several compound classes in a desymmetrization reaction upon de novo generation of chirality.
- Rudroff, Florian,Rydz, Joanna,Ogink, Freek H.,Fink, Michael,Mihovilovic, Marko D.
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p. 1436 - 1444
(2008/09/17)
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- Copper-in-charcoal (Cu/C): Heterogeneous, copper-catalyzed asymmetric hydrosilylations
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Asymmetric copper chemistry ... done heterogeneously? It's doable: Copper-incharcoal (Cu/C) is introduced as an easily prepared catalyst that is readily converted in situ into a nonracemically ligated form of copper hydride that effects asymmetric hydrosilylations. DTBM = 3,5-di-tert-butyl-4- methoxydiphenylphosphinyl. (Figure Presented)
- Lipshutz, Bruce H.,Frieman, Bryan A.,Tomaso Jr., Anthony E.
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p. 1259 - 1264
(2007/10/03)
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- Potassium trifluoro(organo)borates in rhodium-catalyzed 1,4-additions to α,β-unsaturated esters
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This letter describes an efficient and enantioselective conjugate addition of highly stable potassium trifluoro(organo)borates to α,β- unsaturated esters. This reaction, catalyzed by chiral rhodium(I) complexes, affords Michael adducts with high yields an
- Navarre, Laure,Pucheault, Mathieu,Darses, Sylvain,Genet, Jean-Pierre
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p. 4247 - 4250
(2007/10/03)
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- Family clustering of Baeyer-Villiger monooxygenases based on protein sequence and stereopreference
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(Chemical Equation Presented) The identification of enzyme pairs with overlapping substrate specificity and enantiocomplementary transformations is a key challenge in biocatalysis. Enantio and regiodivergent Baeyer-Villiger oxidations were successfully carried out by using a small library of recombinant Escherichia coli strains expressing monooxygenases of various microbial origin (see picture). The clustering of enzymes based on stereopreference is in good agreement with phylogenetic similarity.
- Mihovilovic, Marko D.,Rudroff, Florian,Groetzl, Birgit,Kapitan, Peter,Snajdrova, Radka,Rydz, Joanna,Mach, Robert
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p. 3609 - 3613
(2007/10/03)
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- Enantiomerically pure rhodium complexes bearing 1,5-diphenyl-1,5- cyclooctadiene as a chiral diene ligand. Their use as catalysts for asymmetric 1,4-addition of phenylzinc chloride
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(Chemical Equation Presented) A rhodium complex coordinated with 1,5-diphenyl-1,5-cyclooctadiene (Ph-cod), [RhCl((R)-Ph-cod)]2, was obtained enantiomerically pure through optical resolution of diastereomeric isomers [Rh(Ph-cod)((R)-1,1′-binapht
- Kina, Asato,Ueyama, Kazuhito,Hayashi, Tamio
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p. 5889 - 5892
(2007/10/03)
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- Thermally accelerated asymmetric hydrosilylations using ligated copper hydride
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Exposure of a variety of prochiral substrates to [(R)-(-)-DTBM-SEGPHOS]CuH + PMHS under microwave or conventionally heated conditions reduces reaction times for these hydrosilylations from hours to minutes without significant erosion in ee in most cases.
- Lipshutz, Bruce H.,Frieman, Bryan A.,Unger, John B.,Nihan, Danielle M.
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p. 606 - 614
(2007/10/03)
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