- Asymmetric desymmetrization of meso-tetrahydrofuran derivatives by highly enantiotopic selective C-H oxidation
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Asymmetric desymmetrization of meso-tetrahydrofuran derivatives was successfully achieved by Mn-salen catalyzed enantiotopic selective C-H oxidation, giving optically active lactols (up to 90% ee) which serve as useful chiral building blocks for organic synthesis.
- Miyafuji, Akio,Katsuki, Tsutomu
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Read Online
- (Salen)ruthenium-catalyzed desymmetrization of meso-diols: Catalytic aerobic asymmetric oxidation under photo-irradiation
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Catalytic aerobic oxidation of meso-diols using (nitrosyl)-Ru(salen) 7 as the catalyst under photo-irradiation proceeded with moderate enantioselectivity (up to 67% ee) to give the corresponding lactols.
- Shimizu, Hideki,Nakata, Kenya,Katsuki, Tsutomu
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- Catalytic enantioselective desymmetrization of meso cyclic anhydrides via iridium-catalyzed hydrogenation
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A novel method to desymmetrize meso-anhydrides into lactones via asymmetric hydrogenation catalyzed by the Ir-C3*-TunePhos complex has been developed. Various chiral lactones were synthesized with full conversion and excellent enantioselectivit
- Liu, Tang-Lin,Li, Wei,Geng, Huiling,Wang, Chun-Jiang,Zhang, Xumu
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Read Online
- Simple Preparation of Rhodococcus erythropolis DSM 44534 as Biocatalyst to Oxidize Diols into the Optically Active Lactones
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In the current study, we present a green toolbox to produce ecological compounds like lactone moiety. Rhodococcus erythropolis DSM 44534 cells have been used to oxidize both decane-1,4-diol (2a) and decane-1,5-diol (3a) into the corresponding γ- (2b) and δ-decalactones (3b) with yield of 80% and enantiomeric excess (ee)?=?75% and ee?=?90%, respectively. Among oxidation of meso diols, (?)-(1S,5R)-cis-3-oxabicyclo[4.3.0]non-7-en-2-one (5a) with 56% yield and ee?=?76% as well as (?)-(2R,3S)-cis-endo-3-oxabicyclo[2.2.1]dec-7-en-2-one (6a) with 100% yield and ee?=?90% were formed. It is worth mentioning that R. erythropolis DSM 44534 grew in a mineral medium containing ethanol as the sole source of energy and carbon Chirality 28:623–627, 2016.
- Martinez-Rojas, Enriqueta,Olejniczak, Teresa,Neumann, Konrad,Garbe, Leif-Alexander,Boraty?ski, Filip
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p. 623 - 627
(2016/10/11)
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- Polymerization of epoxide with hydroxylamides as thermally latent initiators
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A new class of thermally latent initiators for the ring-opening polymerization of epoxides has been developed. The latent initiators developed herein were the hydroxylamides 1a, 1b, and 1c, which were synthesized from phthalide, 3-isochromanone, and cis-cyclohexahydrophthalide, respectively, by their ring-opening reactions with pyrrolidine. These hydroxylamides were designed so that their hydroxyl groups could attack the amide moiety intramolecularly upon heating, leading to ring closure and formation of the corresponding lactones while releasing pyrrolidine, the initiator for the anionic ring-opening polymerization of an epoxide. The temperatures at which this thermal dissociation occurred were strongly dependent on the hydroxylamide molecular structure. When using the hydroxylamides as thermally latent initiators, the polymerizations of bisphenol-A diglycidyl ether were investigated at various temperatures. This investigation clarified that the threshold temperature, that is, the temperature at which polymerization was initiated, increased in the order of 1a, 1b, and then 1c.
- Wang, Yanmei,Kimura, Mika,Sudo, Atsushi,Endo, Takeshi
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p. 2611 - 2617
(2016/07/14)
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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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- Aerobic oxidative desymmetrization of meso-diols with bifunctional amidoiridium catalysts bearing chiral N-sulfonyldiamine ligands
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Asymmetric aerobic oxidation of a range of meso- and prochiral diols with chiral bifunctional Ir catalysts is described. A high level of chiral discrimination ability of Cpa? -Ir complexes derived from (S,S)-1,2-diphenylethylenediamine was successfully demonstrated by desymmetrization of secondary benzylic diols such as cis-indan-1,3-diol and cis-1,4-diphenylbutane-1,4-diol, providing the corresponding (R)-hydroxyl ketones with excellent chemo- and enantioselectivities. Enantiotopic group discrimination in oxidation of symmetrical primary 1,4- and 1,5-diols gave rise to chiral lactones with moderate ees under similar aerobic conditions.
- Moritani, Junki,Hasegawa, Yasuharu,Kayaki, Yoshihito,Ikariya, Takao
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supporting information
p. 1188 - 1191
(2014/02/14)
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- Microbial alcohol dehydrogenase screening for enantiopure lactone synthesis: Down-stream process from microtiter plate to bench bioreactor
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One-pot conversion with whole cells of bacteria was performed for biooxidation of meso monocyclic (3a-b) and bicyclic diols (3c-e) into corresponding chiral lactones of bicyclo[4.3.0]nonane structure (2a-b) as well as exo- and endo-bridged lactones with the structure of [2.2.1] (3c-d) and [2.2.2] (3e). Micrococcus sp. DSM 30771 was selected as biocatalyst with significant alcohol dehydrogenase activity. Among tested strains, microbial oxidation of meso diols 3a-e catalyzed by Micrococcus sp. afforded enantiomerically pure ((+)-(2S,3R)-2c (ee = 99%), (+)-(2S,3R)-2e (ee = 99%)) or enriched ((+)-(1S,5R)-2a (ee = 90%), (-)-(1S,5R)-2b (ee = 86%), (+)-(2S,3R)-2d (ee = 80%)) lactone moieties. Comparative study with respect to microbial cultivation as well as biooxidation was undertaken to verify agreement of secondary metabolite biosynthesis in different scales: from MTP (4 mL), across shake flask (100 mL) till bioreactor (4 L). The results from biotransformations showed quite similar dependence in oxidation of all substrates 3a-e in MTP and flasks as well, thereby confirmed the validity and reasonable approach of using MTP for preliminary studies.
- Boratyński,Pannek,Walczak,Janik-Polanowicz,Huszcza,Szczepańska,Martinez-Rojas,Olejniczak
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p. 1637 - 1646
(2015/02/05)
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- One-Pot Bi(OTf)catalyzed oxidative deprotection of tert -butyldimethyl silyl ethers with TEMPO and co-oxidants
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A sequential one-pot synthesis for the oxidation of primary and secondary tert-butyldimethylsilyl (TBDMS) ethers, using catalytic amounts of metal triflates and TEMPO in combination with PhIO or PhI(OAc)in THF or acetonitrile, is described. Acid-sensitive protecting groups such as methylidene, isopropylidene, acetals, and Boc are unaffected under the reaction conditions. Another feature of this procedure is its high selectivity for TBDMS ethers over tert-butyldiphenylsilyl ethers and of aliphatic TBDMS groups over phenolic TBDMS groups. Georg Thieme Verlag Stuttgart - New York.
- Barnych, Bogdan,Vatèle, Jean-Michel
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experimental part
p. 2048 - 2052
(2011/10/19)
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- Catalytic Preparation of Cyclic Carboxylic Esters
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Preparation of cyclic esters by hydrogenation of a carbonyl group in at least one anhydride radical —C(O)—O—C(O)— of a cyclic dicarboxylic or polycarboxylic anhydride by means of hydrogen in the presence of a homogeneous noble metal catalyst, characterized in that the hydrogenation is carried out in a homogeneous reaction mixture using an iridium catalyst. The cyclic esters are obtained in good chemical and optical yields when prochiral anhydrides are used together with chiral iridium catalysts.
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Page/Page column 12
(2009/12/02)
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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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- The crucial role of the nitrogen substituent in the desymmetrisation of cyclic meso-imides using B-Me and B-OMe oxazaborolidine catalysts
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Various cyclic meso-imides have been desymmetrised via enantioselective reduction using two chiral oxazaborolidine catalysts derived from (1R,2S)-cis-1-amino-indan-2-ol followed by the reduction of the hydroxylactam product to give the γ-lactam. The enant
- Barker, Mike D.,Dixon, Rachel A.,Jones, Simon,Marsh, Barrie J.
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p. 11663 - 11669
(2007/10/03)
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- Resolution of fused bicyclic ketones by a recombinant biocatalyst expressing the Baeyer-Villiger monooxygenase gene Rv3049c from Mycobacterium tuberculosis H37Rv
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Recombinant Escherichia coli B834 (DE3) pDB5 expressing the Rv3049c gene encoding a Baeyer-Villiger monooxygenase from Mycobacterium tuberculosis H37Rv was used for regioselective oxidations of fused bicyclic ketones. This whole-cell system represents the first recombinant Baeyer-Villiger oxidation biocatalyst that effectively resolves the racemic starting materials in this series. Within biotransformations using this organism one substrate enantiomer remains in high optical purity, while the second enantiomer is oxidized to one type of regioisomeric lactone preferably.
- Snajdrova, Radka,Grogan, Gideon,Mihovilovic, Marko D.
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p. 4813 - 4817
(2007/10/03)
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- Ligand effects in aluminium-catalyzed asymmetric Baeyer-Villiger reactions
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Asymmetric Baeyer-Villiger oxidations of racemic and prochiral cyclobutanones can be performed with chiral aluminium-based Lewis acids resulting in products with good enantioselectivities in high yields. By employing substituted BINOL derivatives as ligan
- Frison, Jean-Cédric,Palazzi, Chiara,Bolm, Carsten
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p. 6700 - 6706
(2007/10/03)
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- Water-soluble diruthenium complexes bearing acetate and carbonate bridges: Highly efficient catalysts for aerobic oxidation of alcohols in water
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The aerobic oxidation of alcohols in water can be performed efficiently in the presence of a catalytic amount of the water-soluble diruthenium complex Ru2(μ-OAc)3(μ-CO3) under an atmospheric pressure (1 atm) of O2. The Royal Society of Chemistry 2006.
- Komiya, Naruyoshi,Nakae, Takahiro,Sato, Hideomi,Naota, Takeshi
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p. 4829 - 4831
(2007/10/03)
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- CATALYTIC PREPARATION OF CYCLIC CARBOXYLIC ESTERS
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Preparation of cyclic esters by hydrogenation of a carbonyl group in at least one anhydride radical -C(O)-O-C(O)- of a cyclic dicarboxylic or polycarboxylic anhydride by means of hydrogen in the presence of a homogeneous noble metal catalyst, characterized in that the hydrogenation is carried out in a homogeneous reaction mixture using an iridium catalyst. The cyclic esters are obtained in good chemical and optical yields when prochiral anhydrides are used together with chiral iridium catalysts.
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Page/Page column 28
(2008/06/13)
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- Regiodivergent Baeyer-Villiger oxidation of fused ketone substrates by recombinant whole-cells expressing two monooxygenases from Brevibacterium
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Microbial Baeyer-Villiger oxidations of fused bicyclic ketones with a cyclobutanone structural motif were investigated using recombinant Escherichia coli cells expressing two monooxygenases from Brevibacterium. In a kinetic resolution process fused ketones were transformed to regioisomeric lactones: 'normal' lactones were generated by migration of the more substituted carbon atom and 'abnormal' lactones resulted from migration of the less substituted carbon atom. The two Baeyer-Villigerases demonstrated a significantly different stereoselectivity for the regiodivergent biotransformation.
- Mihovilovic, Marko D.,Kapitán, Peter
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p. 2751 - 2754
(2007/10/03)
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- Asymmetric Baeyer-Villiger oxidation: Control of stereoelectronic demand
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The recent development of asymmetric Baeyer-Villiger oxidation of prochiral and racemic ketones is briefly summarized, focusing on the regio- and stereocontrol of the oxidation attained by regulating the stereoelectronic demand in the step of rearrangemen
- Katsuki
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p. 1859 - 1870
(2007/10/03)
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- Asymmetric electrochemical lactonization of diols on a chiral 1-azaspiro[5.5]undecane N-oxyl radical mediator-modified graphite felt electrode
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A graphite felt electrode modified with (6S,7R,10R)-4-amino-2,2,7-trimethyl-10-isopropyl-1-azaspiro[5.5]undecane N-oxyl was prepared for electrocatalytic oxidation of diols; electrolysis of diols on the modified electrode yielded optically active lactones (92.0-96.4%), with an enantiopurity of 82-99% ee.
- Kashiwagi, Yoshitomo,Kurashima, Futoshi,Chiba, Shinya,Anzai, Jun-Ichi,Osa, Tetsuo,Bobbitt, James M.
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p. 114 - 115
(2007/10/03)
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- Catalytic asymmetric oxidative lactonizations of meso-diols using a chiral iridium complex
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A chiral amino alcohol/Ir complex catalyzes the asymmetric oxidative lactonizations of meso-diols to give the corresponding lactones in up to 81% ee.
- Suzuki, Takeyuki,Morita, Kenji,Matsuo, Yoshimi,Hiroi, Kunio
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p. 2003 - 2006
(2007/10/03)
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- Oxidation of alcohols with nitroxyl radical under polymer-supported two-phase conditions
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The oxidation of alcohols to carbonyl compounds was studied using potassium hexacyanoferrate(III) mediated by nitroxyl radical as the catalyst under polymer-supported organic-aqueous two-phase conditions. Primary alcohols are readily oxidized to the corresponding aldehydes in excellent yield with no over-oxidation to carboxylic acids. Secondary alcohols are converted to the corresponding ketones with a much lower efficiency. The oxidation reactions of primary alcohols in the presence of secondary alcohols is strongly favored. Primary-secondary diols are selectively transformed into hydroxy aldehydes with small amounts of ketoaldehydes, the amount of isomeric keto alcohols remaining is less than 1%.
- Yoshitomo, Kashiwagi,Chiba, Shinya,Anzai, Jun-ichi
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p. 1545 - 1549
(2007/10/03)
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- An aqueous silica gel disperse electrolysis system. N-Oxyl-mediated electrooxidation of alcohols
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N-Oxyl-mediated electrooxidation of alcohols was performed in an aqueous silica gel disperse system. The newly devised electrolysis system offers an organic solvent-free and operationally simple procedure for oxidation of alcohols and could be successfully applied to kinetic resolution of sec-alcohol as well as enantioselective oxidation of meso-1,4-diol affording optically active γ-lactone.
- Tanaka, Hideo,Kawakami, Yusuke,Goto, Kentaro,Kuroboshi, Manabu
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p. 445 - 448
(2007/10/03)
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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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p. 2441 - 2446
(2007/10/03)
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- Resolution and stereoselective synthesis of the herpes thymidine kinase inhibitor L-653180
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Resolution of L-653180, (±)-9-{[(Z)-2-(hydroxymethyl)cyclohexyl]-methyl}guanine, a racemic, nonsubstrate inhibitor of HSV-TK, was achieved and the absolute stereochemistry of the enantiomers was determined. Enzyme inhibition was shown to reside in the ena
- Von Langen, Derek J.,Tolman
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p. 677 - 681
(2007/10/03)
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- Asymmetric Catalytic Reduction of meso-Imides
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A thiazazincolidine complex, 1, was shown to be an excellent catalyst for enantioselective reduction with bis(2,6-dimethylphenoxy)borane (BDMPB) of meso N-phenylimides in high ee to the corresponding hydroxy lactams, which were eventually converted to the corresponding lactones of high optical purity.
- Kang, Jahyo,Lee, Jun Won,Kim, Joo In,Pyun, Chongsuh
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p. 4265 - 4268
(2007/10/02)
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- Metal-catalysed Enantiospecific Aerobic Oxidation of Cyclobutanones
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The metal-catalysed aerobic oxidation of substituted racemic cyclobutanones provides optically active lactones with enantioselectivities of up to 95percent e.e.
- Bolm, Carsten,Schlingloff, Gunther
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p. 1247 - 1248
(2007/10/02)
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- Benzyl Methyl (S)-2-(p-Tolylsulfinyl)maleate, an Efficient Dienophile in Asymmetric Diels-Alder Reactions
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The enantiomerically pure dienophile 3 was readily prepared in a three-step sequence from benzyl acetate and (-)-(S)-menthyl p-toluenesulfinate (46percent overall yield).This vinyl sulfoxide reacted in high
- Alonso, Ines,Carretero, Juan C.,Ruano, Jose L. Garcia
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p. 1499 - 1508
(2007/10/02)
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- Oxazaborolidine catalyzed enantioselective reductions of cyclic meso-imides
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A new asymmetric reduction method for meso-imides is reported. Treatment of various imides with a mixture of a chiral oxazaborolidine and BH3 leads to a mixture of cis- and trans-hydroxylactams and, after subsequent ethanolysis, to the correspo
- Romagnoli, Romeo,Roos, Eric C.,Hiemstra, Henk,Moolenaar, Marinus J.,Nico Speckamp,Kaptein, Bernard,Schoemaker, Hans E.
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p. 1087 - 1090
(2007/10/02)
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- Oxidation of Diols to Lactones by Nocardia corallina B-276
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Several synthetically useful achiral and chiral lactones with high optical purity were prepared by whole-cell oxidation of diols with Nocardia corallina.The absolute stereochemistry of the newly created stereogenic centers was established by comparison with known compounds.In all cases the products were derived fron the oxidation of the pro-S hydroxymethylene group.
- Luna, Hector,Prasad, Kapa,Repic, Oljan
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p. 303 - 306
(2007/10/02)
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- Enantioselective reduction of meso-cyclic-1,2-dicarboxylic anhydrides and 1,2-dicarboximides: Asymmetric synthesis of bicyclic lactones and hydroxylactams
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Chiral bicyclic lactones (3,8,9) and bicyclic hydroxylactams (10-13) were synthesized by highly enantioselective reduction of meso-cyclic-1,2- dicarboxylic anhydrides (1, 4) and meso-cyclic-1,2-dicarboximides (2) with lithium aluminum hydride (LiAlH4)-alcohol(ROH)-(R)- or (S)-1,1'-bi-2- naphthol complex [(R)- or (S)-BINAL-H(ROH)]. Treatment of the hydroxylactams (10-13) with triethylsilane (Et3SiH) and trifluoroacetic acid (CF3CO2H) gave chiral bicyclic lactams (14, 15) in quantitative yields. Removal of the N-4-methoxyphenyl group of the lactams (14, 15) with cerium(IV) ammonium nitrate (CAN) proceeded smoothly to give the corresponding N-unsubstituted lactams (16, 17) in high optical purity.
- Matsuki,Inoue,Ishida,Takeda,Nakagawa,Hino
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- Asymmetric synthesis of a potent and selective competitive NMDA antagonist
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(2R,4R,5S)-2-Amino-4,5-(1,2-cyclohexyl)-7-phosphonoheptanoic acid (15) has been prepared by an efficient nine-step route (16% overall yield) which uses chemoenzymatic processes to establish all absolute stereochemistry. This compound was found to be the m
- Hamilton,Huang,Yang,Patch,Narayanan,Ferkany
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p. 7263 - 7270
(2007/10/02)
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- Benzyl Methyl (S)-2-(p-Tolylsulfinyl)maleate: An Efficient Dienophile for the Enantioselective Synthesis of Cyclohexadienes
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The new dienophile, benzyl methyl (S)-2-(p-tolylsulfinyl)maleate, readily prepared in two steps from benzyl acetate, reacts with a wide variety of 1,3-dienes, under catalysis by TiCl4, in a very regioselective and stereoselective manner to give optically
- Alonso, Ines,Carretero, Juan C.,Ruano, Jose L. Garcia
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p. 3231 - 3232
(2007/10/02)
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- HIGHLY ENANTIOSELECTIVE REDUCTION OF MESO-CYCLIC-1,2-DICARBOXIMIDES. ASYMMETRIC SYNTHESIS OF BICYCLIC 2-PYRROLIDINONE AND ITS 5-HYDROXY CONGENER
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Bicyclic-5-hydroxy-2-pyrrolidinones (2a-f) were synthesized with high enantioselectivity by the reduction of meso-cyclic-1,2-dicarboximides (1a-f) with lithium aluminum hydride (LiAlH4)-methanol(MeOH)-1,1-bi-2-naphthol complex (BINAL-H).Treatment of 2a-f with triethylsilane (Et3SiH) and trifluoroacetic acid (CF3CO2H) gave optically active 2-pyrrolidinones (3a-f) in quantitative yields.For the absolute configuration correlation, 2a-d were converted into known lactones (4a-d).
- Matsuki, Kenji,Inoue, Hirozumi,Ishida, Akihiko,Takeda, Mikio
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p. 937 - 940
(2007/10/02)
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- Stereoselective synthesis of a trans-octahydroindole derivative, precursor of trandolapril (RU 44 570), an inhibitor of angiotensin converting enzyme
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We describe a stereoselective synthesis of the trans-octahydroindole-2-carboxylic acid 2 a key intermediate in the elaboration of Trandolapril (RU 44 570) 1. The optically active starting material used was obtained by an enzymatic hydrolysis.
- Brion,Marie,Mackiewicz,Roui,Buendia
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p. 4889 - 4892
(2007/10/02)
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- Highly Diastereoselective Alcoholysis of ?-Symmetric Dicarboxylic Acid Anhydrides Using 1-Phenyl-3,3-bis(trifluoromethyl)propan-1,3-diol
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Highly diastereoselective alcoholysis of ?-symmetric dicarboxylic acid anhydrides was performed using 1-phenyl-3,3-bis(trifluoromethyl)propan-1,3-diol.The importance of the geminally trifluoromethylated carbinol moiety for achieving a high degree of chiral induction was confirmed from lower diastereoselectivity with the hydroxyl protected 1,3-diol or with the similar 1,3-diols having hydrocarbon substituents instead of the trifluoromethyl group.
- Suda, Yoshimitsu,Yago, Seiji,Shiro, Motoo,Taguchi, Takeo
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p. 389 - 392
(2007/10/02)
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- Enzymes in organic synthesis 49. Resolutions of racemic monocyclic esters with pig liver esterase
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Pig liver esterase (PLE)- catalyzed hydrolyses of the racemic methyl esters of cyclobutane-, cyclohexane-, and cyclohex-4-ene-carboxylic acids bearing cis-2-methyl or cis-2-bromomethyl substituents are highly stereoselective, giving the corresponding acid products of ≥ 97% ee. The stereoselectivity of the enzyme exhibits the expected reversal for such compounds, with the absolute configurations of the cyclobutane and cyclohexame acids being of the opposite absolute configuration type, and cyclopentane substrates such as cis-1-carbomethoxy-2-methylcyclopentane representing the change-over structures and giving products of only 22%ee. This stereoselectivtiy reversal, and the absolute configurations preferred, are as predicted by the recently proposed active site model for the enzyme.
- Toone,Jones
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p. 207 - 222
(2007/10/02)
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- A Study of Stereoselective Hydrolysis of Symmetrical Diesters with Pig Liver Esterase
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Pig liver esterase (PLE) catalyzed hydrolysis of dimethyl esters of symmetrical dicarboxylic acids, including meso-diacids, cis-1,2-cycloalkanedicarboxylic acids, and diacids with a prochiral center, was studied with 14 substrates.The products of these stereoselective hydrolyses are chiral monoesters of dicarboxylic acids, with an enantiomeric excess (e.e.) from 10percent to 100percent.Some of these optically active monoesters are valuable synthons in natural products synthesis.An additivity pattern of α- and β-substituents with the glutaric esters on the stereoselectivity of enzymatic hydrolysis was observed.Analysis of the experimental results leads to a model of enzyme stereoselectivity of diester hydrolysis in which the substitution pattern at α- and β-C-atoms is found to determine the absolute configuration of the resulting monoester.
- Mohr, Peter,Waespe-Sarcevic, Nada,Tamm, Christoph,Gawronska, Krystyna,Gawronsky, Jacek K.
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p. 2501 - 2511
(2007/10/02)
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- AN ASYMMETRIC SYNTHESIS OF BICYCLIC LACTONES AND ITS APPLICATION TO THE ASYMMETRIC SYNTHESIS OF (1R,3S)-CIS-CHRYSANTHEMIC ACID
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Optically active bicyclic lactones are synthesized from imides, derived from (R)-(-)-2-amino-2-phenylethanol and meso-cyclic-1,2-cis-dicarboxylic acids, by successive treatment with sodium bis(2-methoxyethoxy)aluminum hydride and sodium borohydride, followed by acid hydrolysis.This reaction is successfully applied to the asymmetric synthesis of (1R,3S)-cis-chrysanthemic acid.
- Mukaiyama, Teruaki,Yamashita, Hiroyuki,Asami, Masatoshi
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p. 385 - 388
(2007/10/02)
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