- An aerobic, organocatalytic, and chemoselective method for Baeyer-Villiger oxidation
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(Chemical Equation Presented) Highly chemoselective Baeyer-Villiger oxidations can be performed in the presence of other reactive functionalities such as alcohols, olefins, and sulfides, which would undergo electrophilic oxidation under conventional conditions (see scheme). [DMRFlEt] +[ClO4]- (depicted blue) is a new class of flavin compound that catalyzes aerobic Baeyer-Villiger oxidations in the presence of Zn dust as the electron source.
- Imada, Yasushi,Iida, Hiroki,Murahashi, Shun-Ichi,Naota, Takeshi
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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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- Acetic Acid as a Highly Reactive and Easily Separable Catalyst for the Oxidative Cleavage of Tetrahydrofuran-2-methanols to γ-Lactones
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[4-Iodo-3-(isopropylcarbamoyl)phenoxy]acetic acid was developed as a highly reactive and easily separable catalyst for the oxidative cleavage of tetrahydrofuran-2-methanols to γ-lactones in the presence of Oxone (2KHSO 5 ·KHSO 4 ·K 2 SO 4) as the co-oxidant. The reactivity of this new catalyst was considerably greater than that of our previously reported catalyst, 2-iodo-N-isopropylbenzamide. The new catalyst and product were easily separated by only liquid-liquid separation without chromatography. In addition, using a mixture of nitromethane and N, N-dimethylformamide as the solvent and heating enabled a low catalyst loading, a short reaction time, and high product yield. Oxidative cleavage using the new catalyst can be used as a practical and efficient method for synthesizing γ-lactones.
- Yakura, Takayuki,Fujiwara, Tomoya,Nishi, Hideyuki,Nishimura, Yushi,Nambu, Hisanori
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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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- 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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- Design of peptide-containing: N 5-unmodified neutral flavins that catalyze aerobic oxygenations
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Simulation of the monooxygenation function of flavoenzyme (Fl-Enz) has been long-studied with N5-modified cationic flavins (FlEt+), but never with N5-unmodified neutral flavins (Fl) despite the fact that Fl is genuinely equal to the active center of Fl-Enz. This is because of the greater lability of 4a-hydroperoxy adduct of Fl, FlOOH, compared to those of FlEt+, FlEtOOH, and Fl-Enz, FlOOH-Enz. In this study, Fl incorporated into a short peptide, flavopeptide (Fl-Pep), was designed by a rational top-down approach using a computational method, which could stabilize the corresponding 4a-hydroperoxy adduct (FlOOH-Pep) through intramolecular hydrogen bonds. We report catalytic chemoselective sulfoxidation as well as Baeyer-Villiger oxidation by means of Fl-Pep under light-shielding and aerobic conditions, which are the first Fl-Enz-mimetic aerobic oxygenation reactions catalyzed by Fl under non-enzymatic conditions.
- Arakawa, Yukihiro,Yamanomoto, Ken,Kita, Hazuki,Minagawa, Keiji,Tanaka, Masami,Haraguchi, Naoki,Itsuno, Shinichi,Imada, Yasushi
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- Silyl peroxides as effective oxidants in the Baeyer-Villiger reaction with chloroaluminate(III) ionic liquids as catalysts
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A new application of silyl peroxides as oxidants in the Baeyer-Villiger oxidation of cyclic ketones in chloroaluminate(III) ionic liquids is described. Among the silyl peroxides, the reactivity of two groups of peroxides was studied: bis(silyl) and t-butyl silyl peroxides possessing different structured substituents attached to the Si atom. It was shown that the acidic 1-hexyl-3-methylimidazolium chloroaluminate(III) ionic liquid (molar ratio of AlCl3 in ionic liquid: 0.67) present in the oxidation of cyclic ketones with bis(silyl) peroxides acts as the catalyst. In this variant of the reaction, the reactivities of bis(silyl) peroxides decrease in the following order: bis(trimethylsilyl) peroxide > bis(vinyldimethylsilyl) peroxide > bis(phenyldimethylsilyl) peroxide > bis(diphenylmethylsilyl) peroxide. A variety of cyclic ketones such as cyclobutanone, 3-substituted cyclobutanones, cyclopentanone, cyclohexanone, 2-methylcyclohexanone, 4-methylcyclohexanone, 2-adamantanone and norcamphor were oxidised to their corresponding lactones with high yields (49-100%). When t-butyl silyl peroxides and neutral chloroaluminate(III) ionic liquids (molar ratio of AlCl3 in ionic liquid: 0.5) were utilised in the Baeyer-Villiger oxidation, the studied ionic liquid acted as the reagent. Here, phenyldimethyl(t-butylperoxy)silane was the most efficient oxidant in the oxidation of cyclobutanone to γ- butyrolactone (70% yield). Other peroxides, including trimethyl(t-butylperoxy) silane, vinyldimethyl(t-butylperoxy)silane and diphenylmethyl-(t-butylperoxy) silane, were less reactive oxidants. Two variants of the Baeyer-Villiger reaction mechanism are postulated.
- Baj, Stefan,S?upska, Roksana,Chrobok, Anna,Drozdz, Agnieszka
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- Dehydrogenative lactonization of diols in aqueous media catalyzed by a water-soluble iridium complex bearing a functional bipyridine ligand
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A new catalytic system for the dehydrogenative lactonization of a variety of benzylic and aliphatic diols in aqueous media was developed. By using a water-soluble, dicationic iridium catalyst bearing 6,6′-dihydroxy-2, 2′-bipyridine as a functional ligand, highly atom economical and environmentally benign synthesis of various lactones was achieved in good to excellent yields. Recovery and reuse of the catalyst were also accomplished by a simple phase separation and the recovered catalyst maintained its high activity at least until the fifth run. Copyright
- Fujita, Ken-Ichi,Ito, Wataru,Yamaguchi, Ryohei
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- Asymmetric Baeyer-Villiger oxidation of prochiral cyclobutanones using a chiral cationic palladium(II) 2-(phosphinophenyl)pyridine complex as catalyst
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Chiral cationic palladium(II) 2-(phosphinophenyl)pyridine (1a) complex was found to be an effective catalyst for asymmetric Baeyer-Villiger oxidation of prochiral cyclobutanones. For example, good and excellent enantioselectivities (80% and >99% ees) were
- Ito, Katsuji,Ishii, Ayako,Kuroda, Tomomi,Katsuki, Tsutomu
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- CATALYTIC REGIOSELECTIVE DEHYDROGENATION OF UNSYMMETRICAL α,ω-DIOLS USING RUTHENIUM COMPLEXES
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Ruthenium complex catalyzed regioselective dehydrogenation of unsymmetrically substituted 1,4- and 1,5-diols in the presence of α,β-unsaturated ketone as a hydrogen acceptor and triethylamine gave β-substituted γ-lactones and γ-substituted δ-lactones as major products, respectively.
- Ishii, Youichi,Osakada, Kohtaro,Ikariya, Takao,Saburi, Masahiko,Yoshikawa, Sadao
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- Highly enantioselective Baeyer-Villiger oxidation using Zr(salen) complex as catalyst
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(R,R)-Zr(salen) complex was found to serve as an efficient catalyst for asymmetric Baeyer-Villiger oxidation of pro-chiral and racemic ketones using urea·hydrogen peroxide as the terminal oxidant: for example, high enantioselectivity of 87% ee was achieve
- Watanabe, Akira,Uchida, Tatsuya,Ito, Katsuji,Katsuki, Tsutomu
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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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- 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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- 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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- 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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- Construction of a new asymmetric reaction site: Asymmetric 1,4-addition of thiol using pentagonal bipyramidal Hf(salen) complex as catalyst
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Pentagonal bipyramidal Hf(salen) complex 1 was found to serve as a catalyst for 1,4-addition reaction of thiol to N-(2-alkenoyl)-2-oxazolidinones.
- Matsumoto, Kazuhiro,Watanabe, Akira,Uchida, Tatsuya,Ogi, Kayoko,Katsuki, Tsutomu
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- Regioselective Hydrogenation of Unsymmetrically Substituted Cyclic Anhydrides Catalyzed by Ruthenium Complexes with Phosphine Ligands
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Regioselective hydrogenation of unsymmetrically substituted cyclic anhydrides catalyzed by ruthenium complexes with mono-, di-, or triphosphine ligands produced the corresponding two isomeric lactones, where the regioselectivity was influenced by the bulkiness of substituent(s) on the anhydrides and of the phosphine ligands of catalyst.
- Ikariya, Takao,Osakada, Kohtaro,Ishii, Youichi,Osawa, Shoichi,Saburi, Masahiko,Yoshikawa, Sadao
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- Rational Construction of an Artificial Binuclear Copper Monooxygenase in a Metal-Organic Framework
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Artificial enzymatic systems are extensively studied to mimic the structures and functions of their natural counterparts. However, there remains a significant gap between structural modeling and catalytic activity in these artificial systems. Herein we report a novel strategy for the construction of an artificial binuclear copper monooxygenase starting from a Ti metal-organic framework (MOF). The deprotonation of the hydroxide groups on the secondary building units (SBUs) of MIL-125(Ti) (MIL = Matériaux de l'Institut Lavoisier) allows for the metalation of the SBUs with closely spaced CuI pairs, which are oxidized by molecular O2 to afford the CuII2(μ2-OH)2 cofactor in the MOF-based artificial binuclear monooxygenase Ti8-Cu2. An artificial mononuclear Cu monooxygenase Ti8-Cu1 was also prepared for comparison. The MOF-based monooxygenases were characterized by a combination of thermogravimetric analysis, inductively coupled plasma-mass spectrometry, X-ray absorption spectroscopy, Fourier-transform infrared spectroscopy, and UV-vis spectroscopy. In the presence of coreductants, Ti8-Cu2 exhibited outstanding catalytic activity toward a wide range of monooxygenation processes, including epoxidation, hydroxylation, Baeyer-Villiger oxidation, and sulfoxidation, with turnover numbers of up to 3450. Ti8-Cu2 showed a turnover frequency at least 17 times higher than that of Ti8-Cu1. Density functional theory calculations revealed O2 activation as the rate-limiting step in the monooxygenation processes. Computational studies further showed that the Cu2 sites in Ti8-Cu2 cooperatively stabilized the Cu-O2 adduct for O-O bond cleavage with 6.6 kcal/mol smaller free energy increase than that of the mononuclear Cu sites in Ti8-Cu1, accounting for the significantly higher catalytic activity of Ti8-Cu2 over Ti8-Cu1.
- Feng, Xuanyu,Song, Yang,Chen, Justin S.,Xu, Ziwan,Dunn, Soren J.,Lin, Wenbin
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- Efficient Oxidative Cleavage of Tetrahydrofuran-2-methanols to γ-Lactones by a 2-Iodobenzamide Catalyst in Combination with Oxone
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An environmentally friendly oxidative cleavage of tetrahydrofuran-2-methanols to the corresponding γ-lactones using a catalytic amount of 2-iodo-N-isopropylbenzamide has been developed. The reaction of various tetrahydrofuran-2-methanols with the catalyst in the presence of Oxone (2 KHSO5·KHSO4·K2SO4) as a co-oxidant in DMF at room temperature successfully affords the corresponding lactones in good to high yields, and recovery of the catalyst is readily accomplished using a reductive work-up. This method is notable because it enables the transformation of tetrahydrofuran-2-methanols to γ-lactones under mild conditions without the use of any toxic heavy metals.
- Yakura, Takayuki,Horiuchi, Yuto,Nishimura, Yushi,Yamada, Akihiro,Nambu, Hisanori,Fujiwara, Tomoya
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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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- Pyrazinium salts as efficient organocatalysts of mild oxidations with hydrogen peroxide
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A series of 3-substituted pyrazinium tetrafluoroborates was prepared as simple analogues of flavinium salts which are efficient organocatalysts for oxidations with hydrogen peroxide. It was shown that pyrazinium derivatives with an electron-withdrawing su
- Menova, Petra,Kafka, Frantisek,Dvorakova, Hana,Gunnoo, Smita,Sanda, Miloslav,Cibulka, Radek
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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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- Influence of hydroperoxides on the enantioselectivity of metal-catalyzed asymmetric Baeyer-Villiger oxidation and epoxidation with chiral ligands
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Chiral hydroperoxides have a significant influence on the enantioselectivity of the metal-catalyzed asymmetric Baeyer-Villiger oxidation of cyclic ketones and the epoxidation of allylic alcohols, when chiral ligands are employed. If both the ligand and th
- Bolm, Carsten,Beckmann, Oliver,Kuehn, Toralf,Palazzi, Chiara,Adam, Waldemar,Rao, Paraselli Bheema,Saha-Moeller, Chantu R.
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- Ruthenium Complex Catalyzed Regioselective Dehydrogenation of Unsymmetrical α,ω-Diols
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Ruthenium complex catalyzed regioselective dehydrogenation of unsymmetrically substituted 1,4- and 1,5-diols in the presence of such a hydrogen acceptor as α,β-unsaturated ketone gave predominantly β-substituted γ-lactones and γ-substituted δ-lactones, respectively.Among the ruthenium complexes, RuH2(PPh3)4 was the most active and selective catalyst and showed high catalytic activity even at 20 deg C.For example, 2,2-dimethyl-1,4-butanediol was quantitatively converted to dihydro-4,4-dimethyl-2(3H)-furanone and dihydro-3,3-dimethyl-2(3H)-furanone in a ratio of 99.6/0.4 in the presence of 4-phenyl-3-buten-2-one (hydrogen acceptor) and a catalytic amount of RuH2(PPh3)4 at 20 deg C.The proposed main factor controlling the regioselectivity is the steric constraints produced by the substituent(s) of a diol at the coordination step of alkoxy group to ruthenium.
- Ishii, Youichi,Osakada, Kohtaro,Ikariya, Takao,Saburi, Masahiko,Yoshikawa, Sadao
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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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- Aerobic lactonization of diols by biomimetic oxidation
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Coming up for air: Highly efficient aerobic lactonization can be carried out by a biomimetic oxidation system based on coupled redox catalysts (ruthenium catalyst and electron transfer mediators). This system leads to a low-energy electron transfer from diol to molecular oxygen. Various diols were aerobically oxidized to the corresponding five- to nine-membered lactones in good to high yields under mild reaction conditions (see scheme).
- Endo, Yoshinori,Baeckvall, Jan-E.
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- Asymmetric 1,4-hydrosilylations of α,β-unsaturated esters
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Complexing catalytic amounts of CuH with a nonracemic JOSIPHOS or SEGPHOS ligand, together with stoichiometric PMHS, leads to exceedingly efficient and highly enantioselective 1,4-reductions of β,β-disubstituted enoates and lactones. An unprecedented subs
- Lipshutz, Bruce H.,Servesko, Jeff M.,Taft, Benjamin R.
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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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- 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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- ASYMMETRIC SYNTHESIS OF β-SUBSTITUTED γ-BUTYROLACTONES
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Highly optically pure β-substituted γ-butyrolactones (V) were obtained in good yields by the reaction of (E)-(2R,3S)-6-alkylidene-3,4-dimethyl-2-phenylperhydro-1,4-oxazepine-5,7-dione (I) with phenylthiomethyllithium, followed by i) treatment with trimethyloxonium tetrafluoroborate and ii) acid hydrolysis.
- Mukaiyama, Teruaki,Fujimoto, Katsumi,Hirose, Takuji,Takeda, Takeshi
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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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- 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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- 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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- 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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- Enantioselective Metal-catalyzed Baeyer-Villiger Oxidation of Cyclobutanones
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Optically active lactones are obtained by metal-catalyzed aerobic oxidation of prochiral cyclobutanones. Starting from 3-mono-substituted substrates lactones with moderate enantioselectivities (up to 47% ee) have been obtained. Kelly's tricyclic ketone 8
- Bolm, Carsten,Luong, T. Kim Khanh,Schlingloff, Gunther
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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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- Platinum-on-Carbon-Catalyzed Aqueous Oxidative Lactonization of Diols by Using Molecular Oxygen
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A lactonization of various diols catalyzed by platinum on carbon (Pt/C) in water under an atmosphere of molecular oxygen was developed. Derivatives of 1,4- 1,5- and 1,6-diols were transformed into the corresponding five-, six-, and seven-membered lactones by the present oxidative lactonization method.
- Ban, Kazuho,Sajiki, Hironao,Sawama, Yoshinari,Takakura, Ryoya
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- Vaulted biaryls: Efficient ligands for the aluminum-catalyzed asymmetric baeyer-villiger reaction
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Vaulted biaryls (VANOL and VAPOL) have been applied in the aluminum-catalyzed asymmetric Baeyer-Villiger reaction of prochiral 3-substituted cyclobutanones. Optically active γ-butyrolactones are obtained in high yields with enantioselectivities of up to 84% ee.
- Bolm, Carsten,Frison, Jean-Cédric,Zhang, Yu,Wulff, William D.
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- Chemo-enzymatic Baeyer-Villiger oxidation in the presence of Candida antarctica lipase B and ionic liquids
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A new method for the chemo-enzymatic Baeyer-Villiger oxidation of cyclic ketones to lactones has been developed. The influence of reaction parameters and the structure of various ionic liquids were studied. Free Candida antarctica lipase B or Novozyme-435 suspended in an ionic liquid was used as the catalytic phase. The reaction was carried out under mild conditions at room temperature using 30% aq. H2O2 as the oxidation agent. 1-Butyl-3-methyl bistriflimide was the most effective ionic liquid and increased the reaction rate compared to toluene. Lipase exhibited good stability, and the ionic liquid could be easily reused. Therefore, a general chemo-enzymatic method for the oxidation of cyclohexanones and cyclobutanones to obtain adequate lactones in high yields (79-95%) has been proposed.
- Drozdz, Agnieszka,Erfurt, Karol,Bielas, Rafal,Chrobok, Anna
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- Regioselectivity in Nickel(II)-Mediated Oxidations of Diols
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Oxidations of 2- and 4-substituted 1,4-butanediols to their corresponding γ-butyrolactones by the combination of molecular bromine and nickel(II) alkanoate occur with a high degree of regioselectivity.The influence of the alkanoate ligand, of substituents at the 2-position of 1,4-butanediols, and of solvent on oxidation regiocontrol is examined, and comparison of regioselectivity in diol oxidations is made with representative conventional oxidative methods.Regiocontrol in nickel(II)-mediated reactions is proposed to be derived from steric constraints for oxidativehydrogen transfer to the alkanoate ligand of nickel(II) in the diol-associated complex.Alternate use of cobalt(II) alkanoates provides regiocontrol in diol oxidations that is comparable or superior to that obtained with nickel(II) alkanoates in bromine oxidations.
- Doyle, Michael P.,Dow, Robert L.,Bagheri, Vahid,Patrie, William, J.
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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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- 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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- Asymmetric Baeyer-Villiger reaction: Diastereodifferentiating peracid oxidation of chiral acetal in the presence of Lewis acid
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Oxidation of 2 with m-chloroperbenzoic acid in the presence of SnCl4 at -78°C followed by hydrolysis afforded optically active 4 in a quantitative yield. The enantiomeric excess tee) of 4 largely depended on the reaction solvent, the chiral dio
- Sugimura, Takashi,Fujiwara, Yoshihisa,Akira, Tai
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- Enantioselective Baeyer-Villiger oxidations catalyzed by chiral magnesium complexes
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Catalytic enantioselective Baeyer-Villiger oxidations of 3-substituted cyclobutanones with cumene hydroperoxide as oxidant have successfully been performed in the presence of chiral magnesium catalysts. The combination of enantiopure BINOL and a variety o
- Bolm,Beckmann,Cosp,Palazzi
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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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- Acetal Addition to Electron-Deficient Alkenes with Hydrogen Atom Transfer as a Radical Chain Propagation Step
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We describe a visible-light-promoted addition of a hydrogen atom and an acetal carbon toward various electron-deficient alkenes. 1,3-Dioxolane is converted to its radical species in the presence of persulfate and an iridium catalyst upon visible light irradiation, which then reacts with electron-deficient alkenes. The reaction operates via a radical chain mechanism, a less commonly observed pathway for this class of transformation. Hydrogen atom transfer from 1,3-dioxolane to α-malonyl radicals is corroborated by experimental and density functional theory studies.
- Chan, Wei Chuen,Vinod, Jincy K.,Koide, Kazunori
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p. 3674 - 3682
(2021/02/16)
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- Synthesis method of butyrolactone compound
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The invention relates to a synthesis method of a butyrolactone compound. The synthesis method comprises the following step: in the presence of a solvent and a cobalt catalyst, converting an oxetane compound shown as general formula I into a butyrolactone compound shown as general formula II through carbonyl insertion ring expansion reaction in an atmosphere of CO and H2. Compared with an existingmethod for synthesizing butyrolactone through oxetane carbonylation ring expansion reaction in a carbon monoxide atmosphere, the synthesis method of a butyrolactone compound provided by the inventionhas the advantages of excellent catalytic activity, excellent chemical selection, wide substrate applicability, mild reaction conditions and the like; compared with other methods for synthesizing butyrolactone compounds, the method provided by the invention has the advantages of wide substrate range, high atom economy, no need of noble metal catalysis and the like, therefore the method has a wideapplication prospect.
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Paragraph 0019-0054
(2020/07/21)
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- Efficient Synthesis of γ-Lactones by Cobalt-Catalyzed Carbonylative Ring Expansion of Oxetanes under Syngas Atmosphere
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A practical route from oxetane or thietane to γ-(thio)butyrolactone via solvated-proton-assisted cobalt-catalyzed carbonylative ring expansion under syngas atmosphere has been established. A wide variety of γ-(thio)butyrolactones can be afforded in good to excellent yields. The versatility of this method has been well demonstrated in the synthesis of intermediates towards the natural product Arctigenin as well as the pharmaceuticals Baclofen and Montelukast. The observed promoting effect of glycol ether solvent has been rationally interpreted.
- Tang, Yitian,Shen, Chaoren,Yao, Qiyi,Tian, Xinxin,Wang, Bo,Dong, Kaiwu
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p. 5898 - 5902
(2020/10/02)
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- Controllable one-pot synthesis for scaffold diversity: Via visible-light photoredox-catalyzed Giese reaction and further transformation
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This study presents a controllable one-pot synthesis for constructing valuable scaffolds (alcohols, 2,3-dihydrofurans, α-cyano-γ-butyrolactones, and γ-butyrolactones) via a visible-light photoredox-catalyzed Giese reaction and further transformation. This
- Nam, Su Been,Khatun, Nilufa,Kang, Young Woo,Park, Boyoung Y.,Woo, Sang Kook
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p. 2873 - 2876
(2020/03/19)
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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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- Visible-Light Photoredox-Catalyzed Hydroalkoxymethylation of Activated Alkenes Using α-Silyl Ethers as Alkoxymethyl Radical Equivalents
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A new neutral silicon-based traceless activation group (TAG) for visible-light photoredox-catalyzed hydroalkoxymethylation of alkenes is presented. This reaction involves in-situ-generated alkoxymethyl radical via single electron oxidation (SET) of α-TMS-substituted ethers, followed by subsequent conjugate addition to activated alkenes. Various functional groups were tolerated both under mild metal and metal-free conditions to provide good to excellent yields. Furthermore, the addition products were transformed to valuable synthetic building blocks, such as carboxylic acids,-butyrolactones, and complex aryl alkyl ethers.
- Khatun, Nilufa,Kim, Myeong Jun,Woo, Sang Kook
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supporting information
p. 6239 - 6243
(2018/09/27)
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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 Synthesis of 2-Formylpyrrolidines, 2-Pyrrolidinones and 2-Dihydrofuranones via Aerobic Copper-Catalyzed Aminooxygenation and Dioxygenation of 4-Pentenylsulfonamides and 4-Pentenylalcohols
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A new method for the direct conversion of 4-pentenylsulfonamides to 2-formylpyrrolidines and a 2-ketopyrrolidine has been developed. This transformation occurs via aerobic copper-catalyzed alkene aminooxygenation where molecular oxygen serves as both oxidant and oxygen source. The 2-formylpyrrolidines can further undergo oxidative carbon-carbon bond cleavage in situ upon addition of DABCO, providing 2-pyrrolidinones. These transformations have been demonstrated for a range of 4-pentenylsulfonamides. 4-Pentenylalcohols also undergo oxidative cyclization to form γ-lactones predominantly. The reaction is chemoselective, oxidizing one alkene in the presence of others, and is compatible with several functional groups. Application of these reactions to the formal syntheses of baclofen and (+)-monomorine was demonstrated.
- Wdowik, Tomasz,Chemler, Sherry R.
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supporting information
p. 9515 - 9518
(2017/07/25)
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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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- Exceptional activity of gallium(III) chloride and chlorogallate(III) ionic liquids for Baeyer–Villiger oxidation
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Baeyer–Villiger oxidation of cyclic ketones, using H2O2 as the oxidising agent, was systematically studied using a range of metal chlorides in different solvents, and in neat chlorogallate(III) ionic liquids. The extremely high activity of GaCl3 in promoting oxidation with H2O2, irrespective of solvent, was reported for the first time. The activity of all other metal chlorides was strongly solvent-dependent. In particular, AlCl3 was very active in a protic solvent (ethanol), and tin chlorides, SnCl4 and SnCl2, were active in aprotic solvents (toluene and dioxane). In order to eliminate the need for volatile organic solvent, a Lewis acidic chlorogallate(III) ionic liquid was used in the place of GaCl3, which afforded typically 89–94% yields of lactones in 1–120 min, at ambient conditions. Raman and 71Ga NMR spectroscopic studies suggest that the active species, in both GaCl3 and chlorogallate(III) ionic liquid systems, are chlorohydroxygallate(III) anions, [GaCl3OH], which are the products of partial hydrolysis of GaCl3 and chlorogallate(III) anions; therefore, the presence of water is crucial.
- Markiton, Magdalena,Chrobok, Anna,Matuszek, Karolina,Seddon, Kenneth R.,Swadzba-Kwasny, Ma?gorzata
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p. 30460 - 30467
(2019/01/14)
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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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- Lactonization reactions through hydrolase-catalyzed peracid formation. Use of lipases for chemoenzymatic Baeyer-Villiger oxidations of cyclobutanones
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A one-pot chemoenzymatic method has been described for the synthesis of γ-butyrolactones starting from the corresponding ketones through a Baeyer-Villiger reaction. The approach is based on a lipase-catalyzed perhydrolysis for the formation of peracetic acid, which is the responsible for the ketone oxidation. Optimization studies have been performed in the oxidation of cyclobutanone, finding Candida antarctica lipase type B, ethyl acetate and urea-hydrogen peroxide complex as the best system. The relative ratio of these reagents has also been analyzed in depth. This synthetic approach has been successfully extended to a family of 3-substituted cyclobutanones in high substrate concentration, yielding the corresponding lactones with excellent isolated yields and purities, under mild reaction conditions and after a simple extraction protocol.
- González-Martínez, Daniel,Rodríguez-Mata, María,Méndez-Sánchez, Daniel,Gotor, Vicente,Gotor-Fernández, Vicente
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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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- Formation of 3-acyloxy-γ-butyrolactones from 4-pentenols in vanadium-catalyzed oxidations
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O-Acyl derivatives of 3-hydroxy-γ-butyrolactone are formed in up to 20% yield as by-products from 1-alkyl- and 1-phenyl-substituted 4-pentenols and tert-butyl hydroperoxide (TBHP) in vanadium-catalyzed synthesis of (tetrahydrofuran-2-yl)-methanols. The lactones are secondary products formed from (tetrahydrofuran-2-yl)-methanols via hydrogen atom abstraction in positions 4 and 5, as derived from experiments starting from deuterium-labeled alkenols. Stereocenters at tetrahydrofuran carbon 2 and the proximate hydroxyl carbon of the alkanol side chain retain configuration in the course of oxidative tetrahydrofuran conversion. In an atmosphere of nitrogen or argon, no γ-butyrolactone formation occurs, pointing to dioxygen as terminal oxidant for the secondary oxidation. Adding cyclohexa-1,4-diene or γ-terpinene to a solution of a 4-pentenol, TBHP, and a vanadium catalyst exposed to air inhibits formation of γ-butyrolactones. A third approach to prevent γ-butyrolactones from being formed in oxidative 4-pentenol cyclization uses cis-2,6-bis-(methanol)-piperidine instead of N-salicylidene-ortho- aminophenol as tridentate auxiliary for the vanadium catalyst.
- Amberg, Matthias,D?nges, Maike,Stapf, Georg,Hartung, Jens
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p. 5321 - 5331
(2014/07/08)
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- Formation of 3-acyloxy-γ-butyrolactones from 4-pentenols in vanadium-catalyzed oxidations
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O-Acyl derivatives of 3-hydroxy-γ-butyrolactone are formed in up to 20% yield as by-products from 1-alkyl- and 1-phenyl-substituted 4-pentenols and tert-butyl hydroperoxide (TBHP) in vanadium-catalyzed synthesis of (tetrahydrofuran-2-yl)-methanols. The lactones are secondary products formed from (tetrahydrofuran-2-yl)-methanols via hydrogen atom abstraction in positions 4 and 5, as derived from experiments starting from deuterium-labeled alkenols. Stereocenters at tetrahydrofuran carbon 2 and the proximate hydroxyl carbon of the alkanol side chain retain configuration in the course of oxidative tetrahydrofuran conversion. In an atmosphere of nitrogen or argon, no γ-butyrolactone formation occurs, pointing to dioxygen as terminal oxidant for the secondary oxidation. Adding cyclohexa-1,4-diene or γ-terpinene to a solution of a 4-pentenol, TBHP, and a vanadium catalyst exposed to air inhibits formation of γ-butyrolactones. A third approach to prevent γ-butyrolactones from being formed in oxidative 4-pentenol cyclization uses cis-2,6-bis-(methanol)-piperidine instead of N-salicylidene-ortho-aminophenol as tridentate auxiliary for the vanadium catalyst.
- Amberg, Matthias,D?nges, Maike,Stapf, Georg,Hartung, Jens
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p. 5321 - 5331
(2014/12/10)
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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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- 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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- Baeyer-Villiger Oxidation of Cyclobutanones with 10-Methylacridinium as an Efficient Organocatalyst
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Baeyer-Villiger oxidation of cyclobutanones is achieved in current developed protocol with 10-methylacridinium perchlorate (AcrH +ClO4-) as a novel organocatalyst both with irradiation at room temperature and without irradiation at elevated temperature. Excellent yields of the corresponding lactones are obtained and the possible mechanism has been proposed.
- Xu, Hua-Jian,Zhu, Feng-Fei,Shen, Yong-Ya,Wan, Xin,Feng, Yi-Si
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p. 4145 - 4151
(2012/07/27)
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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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- Rh-catalyzed intermolecular reactions of cyclic α-diazocarbonyl compounds with selectivity over tertiary C-H bond migration
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Intermolecular Rh-catalyzed reactions of cyclic α-diazocarbonyl compounds with chemoselectivity over β-hydride elimination are described. These methods represent the first general intermolecular reactions of Rh-carbenoids that are selective over tertiary
- Deangelis, Andrew,Dmitrenko, Olga,Fox, Joseph M.
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supporting information; experimental part
p. 11035 - 11043
(2012/08/28)
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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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