- Aniline-Type Hypervalent Iodine(III) for Intramolecular Cyclization via C?H Bond Abstraction of Hydrocarbons Containing N- and O-Nucleophiles
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We developed a method for the preparation of (diacetoxyiodo)-2-(N-alkylamido)benzene as an aniline-type hypervalent iodine(III). We also achieved direct cyclizations via C?H bond abstraction, such as the Hofmann-L?ffler-Freytag reaction, a direct amination, and a direct lactonization, using the aniline-type hypervalent iodine(III) to obtain corresponding products in high yields. (Figure presented.).
- Nishiguchi, Yuna,Moriyama, Katsuhiko
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supporting information
p. 3354 - 3358
(2021/05/17)
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- Efficient hydrogenation of levulinic acid catalysed by spherical NHC-Ir assemblies with atmospheric pressure of hydrogen
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A practical, efficient, and mild hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) under 1 atm H2was realized by single-sited 3D porous self-supported N-heterocyclic carbene iridium catalysts. Quantitative yields and selectivities were achieved at 0.02 mol% catalyst loading, and the catalyst could be reused for 9 runs without obvious loss of selectivity or activity.
- Liu, Yaoqi,Lu, Zeye,Shen, Lingyun,Tu, Tao,Wu, Jiajie,Zheng, Qingshu
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supporting information
p. 5037 - 5042
(2021/07/29)
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- Biocatalytic Asymmetric Reduction of γ-Keto Esters to Access Optically Active γ-Aryl-γ-butyrolactones
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An efficient stereoselective syntheses of a series of functionalized optically active γ-aryl-γ-butyrolactones is achieved by enzymatic asymmetric reduction of the corresponding sterically demanding γ-keto esters employing wild-type and recombinant alcohol dehydrogenases. The best stereoselectivities for the reduction via hydrogen transfer was obtained with two short chain dehydrogenases (SDRs) of complementary stereospecificity from Aromatoleum aromaticum, namely the Prelog-specific NADH-dependent (S)-1-phenylethanol dehydrogenase [(S)-PED] and the anti-Prelog-specific (R)-1-(4-hydroxyphenyl)-ethanol dehydrogenase [(R)-HPED], respectively.Biotransformations catalyzed by both enzymes, followed by TFA-catalyzed cyclization of the resulting γ-hydroxy esters, furnished the respective (S)- and (R)-configured products with exquisite optical purity (up to >99% ee). The synthetic value was demonstrated on preparative scale for the asymmetric bioreduction of the model compound, methyl 4-oxo-4-phenylbutanoate, affording optically pure (S)-γ-phenyl-γ-butyrolactone (>99% ee) in 67–74% isolated yield at 89–95% conversion depending on the applied scale. (Figure presented.).
- ??d?o-Dobrowolska, Anna,Borowiecki, Pawe?,Heider, Johann,Kroutil, Wolfgang,Reiter, Tamara,Schühle, Karola,Szaleniec, Maciej,Tataruch, Mateusz,Telatycka, Natalia
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supporting information
(2020/04/20)
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- Catalytic Redox Chain Ring Opening of Lactones with Quinones to Synthesize Quinone-Containing Carboxylic Acids
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Catalytic ring opening of five- to eight-membered lactones with quinones is achieved through a redox chain mechanism. With low loading of a simple metal triflate Lewis acid catalyst and a chain initiator, C-H bonds of many quinones were efficiently functionalized with carboxylic acid-containing side chains. This method also features 100% atom economy and wide substrate scope. A novel route to the anti-asthma drug Seratrodast was developed. Mechanism study suggests that the redox chain reaction likely undergoes a carbocation intermediate.
- Xu, Xiao-Long,Li, Zhi
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supporting information
p. 5078 - 5081
(2019/09/03)
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- Combined Photoredox/Enzymatic C?H Benzylic Hydroxylations
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Chemical transformations that install heteroatoms into C?H bonds are of significant interest because they streamline the construction of value-added small molecules. Direct C?H oxyfunctionalization, or the one step conversion of a C?H bond to a C?O bond, could be a highly enabling transformation due to the prevalence of the resulting enantioenriched alcohols in pharmaceuticals and natural products,. Here we report a single-flask photoredox/enzymatic process for direct C?H hydroxylation that proceeds with broad reactivity, chemoselectivity and enantioselectivity. This unified strategy advances general photoredox and enzymatic catalysis synergy and enables chemoenzymatic processes for powerful and selective oxidative transformations.
- Betori, Rick C.,May, Catherine M.,Scheidt, Karl A.
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supporting information
p. 16490 - 16494
(2019/11/03)
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- Indium-Catalyzed Direct Conversion of Lactones into Thiolactones and Selenolactones in the Presence of Elemental Sulfur and Selenium
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The direct conversion of lactones into thiolactones with elemental sulfur (S 8) catalyzed by InCl 3 /PhSiH 3 in a one-pot reaction is described. This catalytic system was successfully applied to the novel preparation of selenolactones from lactones and selenium.
- Sakai, Norio,Horikawa, Shuhei,Ogiwara, Yohei
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p. 565 - 574
(2017/12/26)
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- Asymmetric Organocatalytic One-Pot, Two-Step Sequential Process to Synthesize Chiral Acetal-Containing Polycyclic Derivatives from Cyclic Hemiacetals and Enones
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We have developed an efficient one-pot, two-step sequential process to synthesize biologically and synthetically important chiral acetal-containing polycyclic derivatives. This novel protocol had been proved to proceed via Michael-lactolization-oxocarbenium ion ring-closing sequence, which was initiated by a key reactive enamine intermediate and interrupted the previously established reaction pathway of two different enones used in this work, and generated the corresponding cycloadducts with excellent stereoselectivity bearing up to seven continuous stereocenters. Both chiral and racemic starting cyclic hemiacetals worked well in this strategy. The synthetic applications of the obtained polycyclic products have also been demonstrated.
- Liu, Chao,Liu, Yan-Kai
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supporting information
p. 10450 - 10460
(2018/05/31)
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- Nucleo-Palladation-Triggering Alkene Functionalization: A Route to γ-Lactones
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An unprecedented strategy for the highly effective synthesis of γ-lactones from homoallylic alcohols was achieved by palladium catalysis in one step. The protocol affords aryl, alkyl, and spiro γ-lactones directly from readily available homoallylic alcohols in good yields with excellent functional group tolerance and high chemoselectivity under mild conditions.
- Zheng, Meifang,Chen, Pengquan,Huang, Liangbin,Wu, Wanqing,Jiang, Huanfeng
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supporting information
p. 5756 - 5759
(2017/11/10)
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- Efficient Hydrogenation of Biomass Oxoacids to Lactones by Using NHC–Iridium Coordination Polymers as Solid Molecular Catalysts
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A series of NHC–iridium coordination polymers have proven to be robust, efficient and recyclable solid molecular catalysts toward the hydrogenation of biomass levulinic acid (LA) to γ-valerolactone. Along with quantitative yields attained at 0.01 mol % catalyst loading under 50 atm of H2, the solid molecular catalyst was readily recovered and reused for 12 runs without obvious loss of the selectivity and activity. Remarkably, up to 1.2×105 TON, an unprecedented value could be achieved in this important transformation. In addition, a number of LA homologues, analogues and derivatives were well tolerated to deliver various intriguing and functional lactones in good to excellent yields, which further confirmed the feasibility of the solid molecular catalysts.
- Liu, Yaoqi,Sun, Zheming,Huang, Changyu,Tu, Tao
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p. 355 - 360
(2017/02/05)
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- (HMe 2 SiCH 2) 2: A Useful Reagent for B(C 6 F 5) 3 -Catalyzed Reduction-Lactonization of Keto Acids: Concise Syntheses of (-)- cis -Whisky and (-)- cis -Cognac Lactones
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(HMe 2 SiCH 2) 2 has been utilized as a useful reagent for B(C 6 F 5) 3 -catalyzed reduction-lactonization of keto acids to synthesize γ- and δ-lactones. The process led concisely to (-)- cis -whisky and (-)- cis -cognac lactones in respective overall yields of 32% and 36%.
- Xie, Hengmu,Lu, Ji,Gui, Yingying,Gao, Lu,Song, Zhenlei
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supporting information
p. 2453 - 2459
(2017/10/06)
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- Copper-Catalyzed Oxidative Cyclization of Carboxylic Acids
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A method for converting C-H to C-O bonds through oxidative cyclization of carboxylic acids to generate lactone products is described. The reaction employs catalytic amounts of Cu(OAc)2 and potassium persulfate as the terminal oxidant and is performed open to air in an aqueous acetic acid solvent system. Preliminary mechanistic studies suggest that substrate oxidation likely proceeds by sulfate radical anion and that the Cu catalyst has no influence on the product-determining step. These conclusions differ from related investigations that propose the intermediacy of a carboxylate radical.
- Sathyamoorthi, Shyam,Du Bois
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supporting information
p. 6308 - 6311
(2016/12/23)
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- MnO2-promoted carboesterification of alkenes with anhydrides: A facile approach to γ-lactones
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An efficient carboesterification of alkenes with anhydrides promoted by MnO2 has been developed to afford functionalized γ-lactones in good to excellent yields. This method shows a broad substrate scope and provides a valuable and convenient synthetic tool for constructing γ-lactones.
- Wu, Lihuan,Zhang, Zhenming,Liao, Jianhua,Li, Jianxiao,Wu, Wanqing,Jiang, Huanfeng
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supporting information
p. 2628 - 2631
(2016/02/18)
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- Gallium-catalyzed reductive lactonization of γ-keto acids with a hydrosilane
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Described herein is the GaCl3-catalyzed lactonization of γ-keto carboxylic acids in the presence of PhSiH3 leading to the direct preparation of γ-lactone derivatives. This reducing system showed a relatively wide functional group tolerance.
- Sakai, Norio,Horikawa, Shuhei,Ogiwara, Yohei
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p. 81763 - 81766
(2016/09/09)
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- Iridium-Catalyzed C-C Coupling of a Simple Propargyl Ether with Primary Alcohols: Enantioselective Homoaldol Addition via Redox-Triggered (Z)-Siloxyallylation
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A chiral iridium complex formed in situ from [Ir(cod)Cl]2 and (R)-H8-BINAP is found to catalyze the direct enantioselective C-C coupling of a simple propargyl ether, TIPSOCH2C-CH, with primary alcohols to form γ-hydroxy (Z)-enol silanes with uniformly high enantioselectivity and complete alkene (Z)-stereoselectivity. As corroborated by deuterium labeling studies, these studies represent the first examples of 1,2-hydride shift-enabled π-allyl formation in the context of iridium catalysis.
- Liang, Tao,Zhang, Wandi,Krische, Michael J.
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supporting information
p. 16024 - 16027
(2016/01/15)
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- Hypervalent iodine catalyzed cyclization of aryl-substituted alkanoic acids
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A novel and efficient procedure was developed for direct preparation of aryl-substituted lactones from corresponding aryl-substituted alkanoic acids, catalyzed by the in situ generated hypervalent iodine intermediate from iodobenzene (PhI). In this protocol, aryl-substituted alkanoic acids were treated with m-chloroperbenzoic acid (mCPBA) and KBr in the presence of a catalytic amount of PhI in 2,2,2-trifluoroethanol at room temperature for 24 h, resulting in corresponding aryl lactones in moderate-to-good yields. Copyright
- Li, Tingting,Xiang, Changbin,Zhang, Bijun,Yan, Jie
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p. 854 - 860
(2014/07/07)
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- Ammonium iodide-promoted cyclization of aryl-substituted carboxylic acids
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An efficient procedure was developed for direct preparation of aryl-substituted lactones from corresponding aryl carboxylic acids, which was promoted by ammonium iodide. In this protocol, aryl carboxylic acids were treated with ammonium iodide, potassium bromide, and oxidant Oxone in a mixture of acetonitrile and 2,2,2-trifluoroethanol (6:4) at room temperature for 12 h, resulting in corresponding aryl lactones in moderate to good yields.
- Zhang, Bijun,Han, Liuquan,Li, Tingting,Yan, Jie,Yang, Zhenping
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supporting information
p. 1608 - 1613
(2014/06/09)
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- Preparation of enantioenriched γ-substituted lactones via asymmetric transfer hydrogenation of β-azidocyclopropane carboxylates using the ru-TsDPEN complex
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The asymmetric transfer hydrogenation of racemic β-azidocyclopropane carboxylates has been explored. Ru-TsDPEN B is found to be a good catalyst for the formation of enantioenriched γ-lactones through a four-step sequence of azide reduction/cyclopropane ri
- Su, Yan,Tu, Yong-Qiang,Gu, Peiming
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supporting information
p. 4204 - 4207
(2014/10/15)
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- Enantioselective ketone hydroacylation using noyori's transfer hydrogenation catalyst
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An enantioselective ketone hydroacylation enables the direct preparation of lactones from keto alcohols. The alcohol is oxidized in situ to an aldehyde, obviating the need to prepare sensitive keto aldehyde substrates. Noyori's asymmetric transfer hydroge
- Murphy, Stephen K.,Dong, Vy M.
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p. 5553 - 5556
(2013/05/22)
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- γ-substituted butanolides from cyclopropane hemimalonates: An expedient synthesis of natural (R)-dodecan-4-olide
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Exploration into the reactivity of donor-acceptor cyclopropane hemimalonates has led to the facile synthesis of γ-substituted butanolides. Under microwave irradiation, cyclopropane hemimalonates undergo rapid conversion to butanolides in the presence of i
- Grover, Huck K.,Emmett, Michael R.,Kerr, Michael A.
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supporting information
p. 4838 - 4841
(2013/10/08)
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- A new synthesis of γ-butyrolactones via AuCl3- or Hg(II)-catalyzed intramolecular hydroalkoxylation of 4-bromo-3-yn-1-ols
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An efficient conversion of 4-bromo-3-yn-1-ols to γ-butyrolactones via AuCl3-catalyzed electrophilic cyclization (hydroxyl-assisted regioselective hydration) in wet toluene is described. Various secondary and tertiary alcohols including benzylic systems were found to be equally reactive with moderate to excellent yields obtained in all cases.
- Reddy, Maddi Sridhar,Kumar, Yalla Kiran,Thirupathi, Nuligonda
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p. 824 - 827
(2012/04/05)
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- Efficient synthesis of γ-lactones via gold-catalyzed tandem cycloisomerization/oxidation
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A novel Au-catalyzed tandem cycloisomerization/oxidation of homopropargyl alcohols was developed. Various γ-lactones can be accessed readily by utilizing this strategy. Notably, the mechanism of this reaction is distinctively different from the related Ru-catalyzed reactions where the ruthenium vinylidene intermediate was proposed.
- Shu, Chao,Liu, Meng-Qi,Sun, Yu-Zhe,Ye, Long-Wu
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p. 4958 - 4961,4
(2012/12/12)
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- Efficient synthesis of γ-lactones via gold-catalyzed tandem cycloisomerization/oxidation
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A novel Au-catalyzed tandem cycloisomerization/oxidation of homopropargyl alcohols was developed. Various γ-lactones can be accessed readily by utilizing this strategy. Notably, the mechanism of this reaction is distinctively different from the related Ru-catalyzed reactions where the ruthenium vinylidene intermediate was proposed.
- Shu, Chao,Liu, Meng-Qi,Sun, Yu-Zhe,Ye, Long-Wu
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p. 4958 - 4961
(2013/01/15)
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- Asymmetric synthesis of di- and trisubstituted cyclopropanes through an intramolecular ring closure
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An asymmetric synthesis of di- and trisubstituted cyclopropanes proceeding through an intramolecular ring closure of activated chiral benzyl alcohols has been developed. The chiral alcohol intermediates are obtained from asymmetric reduction of readily av
- Kallemeyn, Jeffrey M.,Mulhern, Mathew M.,Ku, Yi-Yin
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supporting information; experimental part
p. 535 - 538
(2011/05/04)
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- Copper-catalyzed intermolecular oxidative [3 + 2] cycloaddition between alkenes and anhydrides: A new synthetic approach to γ-lactones
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A new copper-catalyzed oxidative [3 + 2] cycloaddition of alkenes with anhydrides using oxygen as the sole oxidant to afford γ-lactones has been developed. This catalyzed cyclization process has a broad substrate scope and affords γ-lactones in good to excellent yields.
- Huang, Liangbin,Jiang, Huanfeng,Qi, Chaorong,Liu, Xiaohang
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supporting information; experimental part
p. 17652 - 17654
(2011/03/16)
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- Novel high-affinity and selective biaromatic 4-substituted γ-hydroxybutyric acid (GHB) analogues as GHB ligands: Design, synthesis, and binding studies
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γ-Hydroxybutyrate (GHB) is a metabolite of γ-aminobutyric acid (GABA) and has been proposed to function as a neurotransmitter or neuromodulator. GHB is used in the treatment of narcolepsy and is a drug of abuse. GHB binds to both GABAB receptors and specific high-affinity GHB sites in brain, of which the latter have not been linked unequivocally to function, but are speculated to be GHB receptors. In this study, a series of biaromatic 4-substituted GHB analogues, including 4′-phenethylphenyl, 4′-styrylphenyl, and 4′-benzyloxyphenyl GHB analogues, were synthesized and characterized pharmacologically in a [3H](E,RS)-(6,7, 8,9-tetrahydro-5-hydroxy-5H-benzocyclohept-6-ylidene)acetic acid ([ 3H]NCS-382) binding assay and in GABAA and GABA B receptor binding assays. The compounds were selective for the high-affinity GHB binding sites and several displayed Ki values below 100 nM. The affinity of the 4-[4′-(2-iodobenzyloxy)phenyl] GHB analogue 17b was shown to reside predominantly with the R-enantiomer (Ki = 22 nM), which has higher affinity than previously reported GHB ligands.
- H?g, Signe,Wellendorph, Petrine,Nielsen, Birgitte,Frydenvang, Karla,Dahl, Ivar F.,Br?uner-Osborne, Hans,Brehm, Lotte,Fr?lund, Bente,Clausen, Rasmus P.
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supporting information; experimental part
p. 8088 - 8095
(2009/12/07)
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- Direct lactone formation by using hypervalent iodine(III) reagents with KBr via selective C-H abstraction protocol
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We have developed a new and reliable method for the direct construction of biologically important aryl lactones and phthalides from carboxylic and benzoic acids, using a combination of hypervalent iodine(III) reagents with KBr.
- Dohi, Toshifumi,Takenaga, Naoko,Goto, Akihiro,Maruyama, Akinobu,Kita, Yasuyuki
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p. 3129 - 3132
(2008/02/09)
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- A convenient route to optically active γ-substituted γ-lactones
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Sodium borohydride reduction of 4-substituted (-)-menthyl/ (-)-bornyl-4-oxobutanoates followed by simple trituration in acidic medium at low temperature resulted in the formation of optically active γ-substituted γ-lactones.
- Karnik, Anil V.,Patil, Sudhir T.,Patnekar, Subodh S.,Semwal, Abha
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p. 1420 - 1422
(2007/10/03)
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- Lipase-Catalyzed Preparation of Optically Active γ-Butyrolactones in Organic Solvents
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Lipases in anhydrous organic solvents catalyze the lactonization of esters of γ-hydroxy carboxylic acids with a high degree of stereospecifity.Under these conditions the lipases exhibit both enantioselectivity and prochiral selectivity.We exploited the enzymes' enantioselectivity for synthesis of chiral lactones from racemic γ-hydroxy esters and their prochiral stereospecifity, i.e. the ability to discriminate between enantiotopic groups of a prochiral molecule, for the enantioconvergent lactonization of symmetrical γ-hydroxy diesters.This approach was used to develop a convenient, high yielding, and stereoselective route to several optically active γ-substituted γ-butyrolactones.
- Gutman, Arie L.,Zuobi, Kheir,Bravdo, Tamar
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p. 3546 - 3552
(2007/10/02)
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- Synthesis of γ-Phenyl-γ-butyrolactone
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γ-Phenyl-γ-butyrolactones have been synthesised by a novel oxidative cyclisation of γ-phenylbutanoic acids by ceric ammonium nitrate.
- Nagarajan, A.,Porchezhiyan, V.,Srinivasaramanujam,Balasubramanian, T. R.
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p. 1202 - 1203
(2007/10/02)
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