- Synthesis of xyloketals, natural products from the mangrove fungus Xylaria sp.
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The xyloketal family of compounds was synthesized by condensation of phloroglucinol (7) or 2,4-dihydroxyacetophenone (15) with the enone 8a or 14 in multistep, one-pot, domino reactions, leading to the xyloketals and 5-demethyl-xyloketals, respectively. I
- Krohn, Karsten,Riaz, Muhammad,Floerke, Ulrich
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Read Online
- HIGH DIASTEREOSELECTION IN THE CLAISEN REARRANGEMENT OF ENANTIOMERICALLY PURE BUTYROLACTONES
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The Claisen rearrangement permits the stereoselective formation of butyrolactone 5b,c or 13b,c through the utilization of enantiomeric lactone 1a and enantiomeric alcohols 2b, ent-2b, 2c, and ent-2c.
- Ziegler, Frederick E.,Thottathil, John K.
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Read Online
- Synthesis and olfactory evaluation of optically active β-alkyl substituted γ-lactones and whiskey lactone analogues
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Optically active β-alkyl substituted γ-lactones and whiskey lactone analogues were synthesized, and the odor properties were evaluated. During the preparation of the chiral intermediates, we found good reaction conditions for the highly enantioselective esterification of 3-arylmethyl-2-methyl-1-propanols to kinetically resolve them. The results of the olfactory evaluations of the synthesized lactones revealed that the alkyl groups on the γ-lactone rings played an important role for the odor profiles.
- Kato, Daiki,Kawasaki, Masashi,Morita, Yuko,Okada, Takuya,Tanaka, Yasuo,Toyooka, Naoki
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- Regioselective Hydrogenation of Itaconic Acid to Γ-Isovalerolactone by Transition-Metal Nanoparticle Catalysts
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Current methods for hydrogenation of bio-derived itaconic acid (IA) lead to a mixture of isomeric lactone products. Transition-metal nanoparticles (TM-NPs), in situ-generated through thermolysis of TM(0) (Ru, Fe, W, Cr) carbonyls, in particular Ru-NPs, were found to catalyze regioselective hydrogenation of IA by syngas (2 H2/CO) into γ-isovalerolactone (GiVL) in approximately 70 % isolated yield. Key sustainability features of this new route include: a one-pot direct transformation of bio-renewable IA into value-added GiVL selectively, use of inexpensive and renewable syngas in aqueous solution, and development of a supported recyclable NP catalyst system, Al2O3-Ru-NPs.
- Gowda, Ravikumar R.,Chen, Eugene Y.-X.
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p. 973 - 977
(2019/02/06)
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- METHOD FOR REDUCTION OF ORGANIC MOLECULES
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A method for the reduction organic molecules comprising a Ruthenium-Triphosphine complex with aromatic ligands at the phosphors which are ortho or meta substituted.
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Paragraph 0050; 0052; 0053; 0054; 0055
(2018/02/06)
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- METHODS OF FORMING DIOL COMPOUNDS
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Methods of forming a C4 to C7 diol compound, the methods including a first step of reacting a C4 to C7 dicarboxylic acid with hydrogen (H2) gas on a first heterogeneous catalyst at a first temperature and a first pressure to form a C4 to C7 lactone; and a subsequent step of reacting the lactone with hydrogen (H2) gas on a second heterogeneous catalyst at a second temperature and a second pressure, wherein the second temperature is lower than the first temperature. Also disclosed are methods of forming a solvent, the methods including reacting a C4 to C7 dicarboxylic acid with hydrogen (H2) gas on a first heterogeneous catalyst at a first temperature and a first pressure to form a solvent. Further disclosed herein are methods that include reacting mevalonolactone with hydrogen (H2) gas on a second heterogeneous catalyst at a second temperature and a second pressure to form a diol compound.
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Paragraph 0115
(2017/11/06)
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- Branched Diol Monomers from the Sequential Hydrogenation of Renewable Carboxylic Acids
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A prominent challenge in replacing petrochemical polymers with bioderived alternatives is the efficient transformation of biomass into useful monomers. In this work, we demonstrate a practical process for the synthesis of multifunctional alcohols from five- and six-carbon acids using heterogeneous catalysts in aqueous media. Design of this process was guided by thermodynamic calculations, which indicate the need for two sequential high-pressure hydrogenations: one, reduction of the acid to a lactone at high temperature; two, further reduction of the lactone to the corresponding diol or triol at low temperature. For example, the conversion of mesaconic acid into (α or β)-methyl-γ-butyrolactone was achieved with 95 % selectivity at a turnover frequency of 1.2 min?1 over Pd/C at 240 °C. Subsequent conversion of (α or β)-methyl-γ-butyrolactone into 2-methyl-1,4-butanediol was achieved with a yield of 80 % with Ru/C at 100 °C. This process is an efficient method for the production of lactones, diols, and triols, all valuable monomers for the synthesis of bioderived branched polyesters.
- Spanjers, Charles S.,Schneiderman, Deborah K.,Wang, Jay Z.,Wang, Jingyu,Hillmyer, Marc A.,Zhang, Kechun,Dauenhauer, Paul J.
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p. 3031 - 3035
(2016/10/11)
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- A sustainable process for the production of 2-methyl-1,4-butanediol by hydrogenation of biomass-derived itaconic acid
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Pd-ReOx/C catalysts with different Re contents were prepared and employed to catalyze the aqueous hydrogenation of itaconic acid in this study. The Pd-ReOx/C catalysts were characterized by XRD, TEM, BET, NH3-TPD and H2-TPR. Results showed that the addition of ReOx species in supported Pd catalysts promoted the direct conversion of itaconic acid to 2-methyl-1,4-butanediol. The promoting effect was ascribed to the interaction between Pd and ReOx species, as has been proved by the characterizations. A 2-methyl-1,4-butanediol yield of above 80% could be obtained over Pd-3ReOx/C under the reaction condition of 180 °C, 4 MPa H2.
- Liu, Xiaoran,Wang, Xicheng,Liu, Qiang,Xu, Guoqiang,Li, Xuemin,Mu, Xindong
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- Direct hydrogenation of biobased carboxylic acids mediated by a nitrogen-centered tridentate phosphine ligand
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A novel nitrogen-centered tridentate ligand was identified from a series of multidentate ligands and applied for the direct hydrogenation of 9 biogenic acids into alcohols, lactones and esters with high yields. Comparison of substrates and ruthenium precursors suggested that the RuII hydride cationic species was more active to transform acids than the corresponding lactone or esters.
- Deng, Li,Kang, Bin,Englert, Ulli,Klankermayer, Jürgen,Palkovits, Regina
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p. 177 - 180
(2016/02/05)
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- Efficient and Selective Cu/Nitroxyl-Catalyzed Methods for Aerobic Oxidative Lactonization of Diols
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Cu/nitroxyl catalysts have been identified that promote highly efficient and selective aerobic oxidative lactonization of diols under mild reaction conditions using ambient air as the oxidant. The chemo- and regioselectivity of the reaction may be tuned by changing the identity of the nitroxyl cocatalyst. A Cu/ABNO catalyst system (ABNO = 9-azabicyclo[3.3.1]nonan-N-oxyl) shows excellent reactivity with symmetrical diols and hindered unsymmetrical diols, whereas a Cu/TEMPO catalyst system (TEMPO = 2,2,6,6-tetramethyl-1-piperidinyl-N-oxyl) displays excellent chemo- and regioselectivity for the oxidation of less hindered unsymmetrical diols. These catalyst systems are compatible with all classes of alcohols (benzylic, allylic, aliphatic), mediate efficient lactonization of 1,4-, 1,5-, and some 1,6-diols, and tolerate diverse functional groups, including alkenes, heterocycles, and other heteroatom-containing groups.
- Xie, Xiaomin,Stahl, Shannon S.
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supporting information
p. 3767 - 3770
(2015/04/14)
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- Aqueous-phase hydrogenation of biomass-derived itaconic acid to methyl-γ-butyrolactone over Pd/C catalysts: Effect of pretreatments of active carbon
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The effect of active carbon pretreatment on the catalytic performance of Pd/C catalysts in the hydrogenation of itaconic acid was studied. The catalysts were prepared by deposition-precipitation and characterized by XRD, BET, NH3-TPD, TEM and F
- Li, Sha,Wang, Xicheng,Liu, Xiaoran,Xu, Guoqiang,Han, Sheng,Mu, Xindong
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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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p. 109 - 112
(2014/01/23)
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- Application of the palladium-catalysed norbornene-assisted catellani reaction towards the total synthesis of (+)-linoxepin and isolinoxepin
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Our ongoing effort towards the development of highly selective transition-metal-catalysed C-H activation processes has led to the expansion of the Catellani reaction. In a Pd0/PdII/Pd IV-catalysed domino reaction, an aryl iodide, alkyl iodide and tert-butyl acrylate were combined to synthesize the carbon framework of the novel lignan (+)-linoxepin. The enantioselective synthesis highlights the work accomplished in our group and provides an excellent procedure for the reliable and scalable synthesis of architecturally complex scaffolds. This report outlines the synthetic approaches towards this interesting class of biologically active molecules. After the key Catellani/Heck reaction, our synthesis features a Leimeux-Johnson oxidation and a titanium tetrachloride mediated aldol condensation. Finally, a tuneable Mizoroki-Heck reaction was performed to furnish not only the natural product (+)-linoxepin but also its isoform, which we have named isolinoxepin. The enantioselective total synthesis of the natural product (+)-linoxepin has been accomplished in eight steps starting from commercial materials. The key Pd-catalysed Catellani step served to combine aryl iodide, alkyl iodide and tert-butyl acrylate in a domino sequence. By tuning the final Heck reaction, both the natural product and its structural isomer were synthesized. Copyright
- Qureshi, Zafar,Weinstabl, Harald,Suhartono, Marcel,Liu, Hongqiang,Thesmar, Pierre,Lautens, Mark
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p. 4053 - 4069
(2014/07/08)
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- TRICYCLIC COMPOUNDS
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The present invention provides a compound of formula I or a pharmaceutically acceptable salt thereof; and its therapeutic uses. The present invention further provides a combination of pharmacologically active agents and a pharmaceutical composition.
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Paragraph 1921; 1922
(2014/06/25)
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- ANTIBACTERIAL COMPOUNDS AND METHODS FOR USE
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The present description relates to compounds and forms and pharmaceutical compositions thereof and methods for use thereof to treat or ameliorate bacterial infections caused by wild-type and multi-drug resistant Gram-negative and Gram-positive pathogens. The present description further relates to a compound having activity toward wild-type and MDR bacteria. The present description also relates to a compound having activity against quinolone-resistant Gram-negative strains (including MDR strains) as well as antibacterial activity to MDR resistant Gram-positive pathogens (including MRSA strains).
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Page/Page column 107-108
(2013/03/28)
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- A versatile aqueous reduction of bio-based carboxylic acids using syngas as a hydrogen source
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Syngas as a versatile hydrogen source: Using readily available and economically favorable syngas as a convenient hydrogen source, an efficient and sustainable aqueous reduction of bio-based carboxylic acids has been achieved over a highly robust catalyst system consisting of gold nanoparticles supported on acid-tolerant single-phase monoclinic zirconia (Au/m-ZrO2). A range of bio-based multifunctional carboxylic acids have been selectively converted into their corresponding lactones or diols in high to excellent yields. Copyright
- Yu, Lei,Du, Xian-Long,Yuan, Jing,Liu, Yong-Mei,Cao, Yong,He, He-Yong,Fan, Kang-Nian
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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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- Synergy between the metal nanoparticles and the support for the hydrogenation of functionalized carboxylic acids to diols on Ru/TiO2
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Ruthenium nanoparticles supported on titania are over three times more active than conventional ruthenium on carbon for the hydrogenation of lactic acid. This superior catalytic activity can be due to a combined action of small ruthenium nanoparticles and the titania support.
- Primo, Ana,Concepcion, Patricia,Corma, Avelino
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scheme or table
p. 3613 - 3615
(2011/04/25)
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- Oxidant-free lactonization of diols using a hydrotalcite-supported copper catalyst
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We newly synthesized well-crystallized hydrotalcite-supported copper nanoparticles, denoted as Cu/HT(c), which acted as a highly efficient heterogeneous catalyst for oxidant-free lactonization of various diols under liquid-phase conditions. The Cu/HT(c) catalyst could be recovered by simple filtration and reused without the significant loss of its activity and selectivity.
- Mikami, Yusuke,Ebata, Kaori,Mitsudome, Takato,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
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experimental part
p. 855 - 861
(2010/09/16)
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- Synthesis of quaternary carbon centers via hydroformylation
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The application of hydroformylation to the synthesis of quaternary carbon centers is reported. The synthesis of the highly substituted carbon is achieved by applying a catalytic amount of 1. Ligand 1 serves as a catalytic directing group by covalently and reversibly binding to both the substrate and catalyst. The intramolecular nature of the directing group strategy accelerates the hydroformylation reaction such that the reaction is performed at mild temperatures (35-55 °C) and with excellent regioselectivity (b:l > 94:6).
- Sun,Frimpong,Tan
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supporting information; experimental part
p. 11841 - 11843
(2010/11/04)
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- Selective and flexible transformation of biomass-derived platform chemicals by a multifunctional catalytic system
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(Figure Presented) A sustainable supply chain: The controlled transformation of the biomassderived platform compounds levulinic acid (LA) and itaconic acid (IA) into the corresponding lactones, diols, or cyclic ethers (see picture) by using a multifunctional molecular catalyst is described.
- Geilen, Frank M. A.,Engendahl, Barhel,Harwardt, Andreas,Marquardt, Wolfgang,Klankermayer, Juergen,Leitner, Walter
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body text
p. 5510 - 5514
(2010/09/16)
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- Supported gold nanoparticles as a reusable catalyst for synthesis of lactones from diols using molecular oxygen as an oxidant under mild conditions
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The oxidative lactonization of various diols using molecular oxygen as a primary oxidant can be efficiently catalyzed by hydrotalcite-supported Au nanoparticles (Au/HT). For instance, lactonization of 1,4-butanediol gave γ-butyrolactone with an excellent turnover number of 1400. After lactonization, the Au/HT can be recovered by simple filtration and reused without any loss of its activity and selectivity.
- Mitsudome, Takato,Noujima, Akifumi,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
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experimental part
p. 793 - 797
(2010/04/23)
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- Exploration of the molecular origin of the azinomycin epoxide: Timing of the biosynthesis revealed
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(Equation Presented) Streptomyces sahachiroi whole cell feeding experiments, utilizing putative precursors labeled with stable isotopes, established that the epoxide unit of the DNA cross-linked agents, azinomycin A and B, proceeds via a valine-dependent pathway and that hydroxylation and dehydration precedes formation of the terminal epoxide. Sodium 3-methyl-2-oxobutenoate, formed through a transimination reaction, was shown to be the penultimate precursor incorporated into the azinomycin epoxide.
- Sharma, Vasudha,Kelly, Gilbert T.,Watanabe, Coran M. H.
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supporting information; experimental part
p. 4815 - 4818
(2009/05/31)
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- Process for preparing alpha- and beta-methyl-gamma-butyrolactone and 3-methyltetrahydrofuran
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The present invention pertains to a novel process for preparing alpha- and beta-methyl-gamma-butyrolactones (MeGBL) and/or 3-Methyltetrahydrofuran (MeTHF) from 3-(hydroxymethyl)tetrahydrofuran (HOMeTHF), 3-formyltetrahydrofuran (FTHF) or a mixture thereof
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- Process for the preparation of 3-methyltetrahydrofuran
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Disclosed is a process for the preparation of 3-methyltetrahydrofuran (MeTHF) from 3-(hydroxymethyl)tetrahydrofuran (HOMeTHF) by contacting HOMeTHF with hydrogen in the presence of an acidic, supported catalyst comprising a Group VIII metal.
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Page/Page column 6-7
(2008/06/13)
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- A convenient route to 1,4-monoprotected dialdehydes, 1,4-ketoaldehydes, γ-lactols and γ-lactones through radical alkylation of α,β-unsaturated aldehydes in organic and organic-aqueous media
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α,β-Unsaturated aldehydes were smoothly alkylated by radicals generated through photosensitised hydrogen abstraction of benzophenone. In this way, and by using 1,3-dioxolane as radical precursor, monoprotected 1,4-dialdehydes were obtained from crotonaldehyde, 2-hexenal, 4-methyl-2-pentenal and cyclohexencarboxyaldehyde in a moderate yield, and in a low yield from β-aryl-α,β-unsaturated aldehydes. With 2-alkyl-1,3-dioxolanes, monoprotected 1,4-ketoaldehydes were analogously prepared. By using methanol, ethanol and isopropanol as radical precursors γ-lactols were likewise obtained from the above aliphatic aldehydes. These single-step syntheses compared favorably with multi-step approaches previously proposed for some of these compounds. The lactols were conveniently oxidized to the corresponding γ-lactones. An alternative to the photosensitisation in organic medium was the use of mixed aqueous-organic solvent and a hydrosoluble photosensitiser (benzophenone disodium disulfonate was prepared for this purpose and successfully used), which allowed a more convenient work up.
- Dondi, Daniele,Caprioli, Ilaria,Fagnoni, Maurizio,Mella, Mariella,Albini, Angelo
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p. 947 - 957
(2007/10/03)
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- Radical reaction by a combination of phosphinic acid and a base in aqueous media
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Treatment of various organic halides with phosphinic acid (hypophosphorous acid) in aqueous ethanol in the presence of a radical initiator and a base gave the corresponding reduced products in high yields. Addition of a base is indispensable for the reduction of halides by phosphinic acid. Allylic ether of o-iodophenol or 2-haloalkanal allylic acetal underwent radical cyclization under the same conditions to afford the corresponding cyclic product in excellent yield. Deuterated phosphinic acid was found to be an efficient chain carrier for the radical deuteration of organic halides. For example, a deuterium oxide solution of deuterated phosphinic acid, potassium carbonate, 2,2′-azobis(isobutyramidine) dihydrochloride as an initiator, and p-iodobenzoic acid was heated at reflux to give p-deuteriobenzoic acid in 94% yield. A mixed dioxane/D2O solvent system combined with DBU and potassium peroxodisulfate was crucial to deuterate hydrophobic substrates in high yields and with high deuterium incorporation. Complete deuterium incorporation was accomplished only by the reaction in D2O without an organic cosolvent and an organic base.
- Yorimitsu,Shinokubo,Oshima
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p. 225 - 235
(2007/10/03)
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- Reduction of organic halides with tri-2-furylgermane: Stoichiometric and catalytic reduction
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Tri-2-furylgermane proved to be an effective reagent for the radical reduction of organic halides. Treatment of 1-bromododecane with tri-2-furylgermane in THF at 25 °C in the presence of a catalytic amount of triethylborane afforded dodecane almost quantitatively. Radical cyclization of 2-iodoethanal allyl acetal afforded five-membered products under the same reaction conditions. These reactions proceeded with NaBH4 in the presence of a catalytic amount of germanium hydride. The reaction took place in water as well as in THF to give the corresponding reduced compounds in good yields.
- Nakamura,Yorimitsu,Shinokubo,Oshima
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p. 747 - 752
(2007/10/03)
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- Raney Nickel: An effective reagent for reductive dehalogenation of organic halides
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Raney Nickel is an effective reagent to achieve the chemoselective reductive dehalogenation of organic halides. Fluorides and vinyl halides are unreactive under the used experimental conditions.
- Barrero,Alvarez-Manzaneda,Chahboun,Meneses,Romera
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p. 485 - 488
(2007/10/03)
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- Highly regioselective intramolecular hydroxymethylation of α,β-unsaturated carboxylic acids
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A convenient synthesis of hydroxy esters 7 and lactones 8 by starting from easily available α,β-unsaturated carbocylic acids 4 is described. The key step of this transformation is a hitherto unknown radical cyclization of silyl esters, which exhibits a high degree of regioselectivity through steric and orbital control.
- Linker, Torsten,Maurer, Michael,Rebien, Frank
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p. 8363 - 8366
(2007/10/03)
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- and Annulation Reactions of α-(Phenylthio) Dicarbonyl Electrophiles with Bis(trimethylsilyl) Enol Ethers: Synthesis of Highly Functionalized Medium Ring Cycles
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The and annulations of bis(trimethylsilyl) enol ethers with 1,4- and 1,5-dicarbonyl electrophiles bearing α-phenylthio substituents leads to the formation of bicyclic and ethers with good regiochemical and stereochemical control.Subsequent oxidation of the phenylthio moiety followed by reduction with SmI2 constitutes a high-yielding and regioselective process for cleavage of the bridging ether linkage.The overal strategy provides a synthetic pathway for the synthesis of highly functionalized medium ring carbocycles.
- Molander, Gary A.,Eastwood, Paul R.
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p. 8382 - 8393
(2007/10/02)
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- Asymmetric Synthesis of a Key Synthetic Precursor for (+)-Strigol and Sorgolactone
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En-route to non-racemic iodomethyl butyrolactone 23g a number of stereoselective 1,4-additions and reductions have been studied.The only satisfactory approach involved baker's yeast reduction (21c->23c) as key step.
- Schroeer, Josef,Welzel, Peter
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p. 6839 - 6858
(2007/10/02)
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- NEW METHODS FOR REDUCTIVE FREE-RADICAL CYCLIZATIONS OF α-BROMOACETALS TO 2-ALKOXYTETRAHYDROFURANS WITH ACTIVATED CHROMIUM(II)-ACETATE
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A method for the synthesis of γ-butyrolactones 6 is described in which the key step is a free-radical cyclization of α-bromoacetals 4 to 2-alkoxytetrahydrofurans 5 in 54-93percent yield induced by activated chromium(II)-acetate.Four new methods have been developed in order to activate the transition metal.Two of them require only catalytic amounts of chromium(II)-acetate, because it can be regenerated in situ chemically or electrochemically.The diastereoselectivity of the cyclization depends on the substitution pattern of 4 and ranges between 30.4:1 and 1:54.8.
- Hackmann, Claus,Schaefer, Hans J.
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p. 4559 - 4574
(2007/10/02)
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- A convenient lactonization of diols to γ- and δ-lactones catalyzed by transition metals polyhydrides
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Transition metal polyhydrides-catalyzed oxidative condensation of diols to 5 and 6-ring lactones was studied.The regioselective dehydrogenation of unsymmetrically substituted 1,4-diols gave β- or γ-substituted γ-lactones in high yields.The mechanism of dehydrogenation under neutral and mild conditions was discussed.
- Lin, Yingrui,Zhu, Xianchao,Zhou, Yuefen
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p. 269 - 274
(2007/10/02)
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- Absolute Configuration and Synthesis of 2-Hydroxy-2-(1-hydroxyethyl)-3-methyl-γ-butyrolactone, a Presumed Pheromone of Ithomiine Butterflies
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2-Hydroxy-2-(1-hydroxyethyl)-3-methyl-γ-butyrolactone (1) is a constituent of scent glands of male ithomiine butterflies.All diastereomers and the respective (3R)-enantiomers were synthesized by starting from rac- or (3S)-3-methyl-γ-butyrolactone 3.Their relative configurations were determined by difference NOE-NMR spectroscopy or by X-ray diffraction analysis.The absolute configuration of the natural product was determined by gas chromatography on a chiral stationary phase of the respective dioxolane derivatives.The natural lactone could be shown to be the .In addition, the corresponding ketone, (2S,3R)-2-acetyl-2-hydroxy-3-methyl-γ-butyrolactone , could be identified as a new natural product from Prittwitzia hymaenea. Key Words: Pheromones / Ithomiinae / Ithomiolide / Keto lactone / Butterflies
- Schulz, Stefan
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p. 829 - 834
(2007/10/02)
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- HIGHLY REGIOSELECTIVE RING-OPENING OF α-SUBSTITUTED CYCLIC ACID ANHYDRIDES CATALYZED BY LIPASE
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Lipase Amano P irreversibly catalyzed a ring-opening of α-substituted cyclic acid anhydrides 1 preferentially at the less hindered carbonyl group to give monoesters with high regioselectivity.
- Hiratake, Jun,Yamamoto, Kazuyoshi,Yamamoto, Yukio,Oda, Jun'ichi
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p. 1555 - 1556
(2007/10/02)
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- Analogues of γ-hydroxybutyric acid. Synthesis and binding studies
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Substituted 4-hydroxybutyric (GHB) or trans-4-hydroxycrotonic acids (T-HCA) and structurally related compounds were synthesized and submitted to [3H]GHB binding. Structure-activity relationship studies highlighted for [3H]GHB binding (a) the necessity of a nonlactonic, relatively extended conformation of the γ-hydroxybutyric chain, (b) the existence of some bulk tolerance in the vicinity of the hydroxyl group, and (c) the high sensitivity toward isosteric replacement of the carboxyl or the hydroxyl groups. T-HCA has been recently identified as a naturally occurring substance in the central nervous system (CNS) and shows a better affinity than GHB. Our findings are in favor of the presence in the CNS of specific GHB binding sites, which are different from the GABA and the picrotoxin binding sites, and for which T-HCA may be an endogenous ligand.
- Bourguignon,Schoenfelder,Schmitt,Wermuth,Hechler,Charlier,Maitre
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p. 893 - 897
(2007/10/02)
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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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p. 2034 - 2039
(2007/10/02)
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- General Synthetic Route to γ-Butyrolactones via Stereoselective Radical Cyclization by Organotin Species
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A new method for the preparation of γ-butyrolactones is described in which the key step is the highly stereoselective radical cyclization of bromoacetals to 2-alkoxytetrahydrofurans in the presence of polymeric or low-molecular weight organotin species. 2-Alkoxytetrahydrofurans can be easily converted into γ-butyrolactones by Jones oxidation.
- Ueno, Yoshio,Moriya, Osamu,Chino, Kunitake,Watanabe, Masaru,Okawara, Makoto
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p. 1351 - 1356
(2007/10/02)
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- HYDROCARBONYLATION DE LACTONES EN PRESENCE DE CATALYSEURS A BASE DE COBALT ET DE RHODIUM
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The hydrocarbonylation of lactones catalysed by rhodium and cobalt complexes is discussed.Rhodium catalysts promote the formation of mono- and di-acids, but with cobalt catalysts homologation takes place yielding lactones and acids.The addition of iodine promotors is essential.
- Bitsi, Gustave,Kheradmand, Houchang,Jenner, Gerard
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p. 115 - 120
(2007/10/02)
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- Method for sterilizing male parts of plants
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3-Substituted-2-carboxyazetidines, their esters and salts are used to sterilize male parts in plants.
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- FACILE OXIDATIVE CYCLIZATION AND CARBONYLATION OF ALLYLIC ALCOHOLS
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Palladium chloride catalyzed reaction of primary, secondary, and tertiary allylic alcohols with carbon monoxide and oxygen, hydrochloric acid, and cupric chloride in tetrahydrofuran affords five-membered ring lactones.
- Alper, Howard,Leonard, Daniele
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p. 5639 - 5642
(2007/10/02)
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- Synthesis of 4-Alkyl-2(5H)-furanones
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An alternative method for the synthesis of 4-alkyl-2(5H)-furanones is described.Intramolecular carbene addition reaction of α-diazo compounds (4) in the presence of rhodium acetate or copper acetylacetonate furnished the bicyclic compounds (5), which were subjected to cyclopropane ring-opening reaction to give the 4-alkyl-4,5-dihydrofuran-2(3H)-ones (6) regioselectively.These compounds (6) were further converted into 4-alkyl-2(5H)-furanones (14) in several steps.Keywords - carbene; intramolecular addition; butenolide; cyclopropanation; ring-opening reaction
- Kametani, Tetsuji,Katoh, Tadashi,Tsubuki, Masayoshi,Honda, Toshio
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- PYRIDINIUM HALIDE-PROMOTED RING-OPENING REACTION OF CYCLOPROPANECARBOXYLIC ACIDS
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Cyclopropanecarboxylic acids when heated at 150 deg C with pyridinium chloride (molten salt) or iodide undergo ring fission giving γ-lactones in one step.Saturated bicyclic substrates give cis products, while an α,β-unsaturated compound does not undergo ring opening and produces a mixture of tricyclic γ- and δ-lactones.
- Buttinelli, Paolo,Gargaro, Giuseppe,Loreto, M. Antonietta,Pellacani, Lucio,Tardella, Paolo A.
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p. 155 - 158
(2007/10/02)
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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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p. 2677 - 2680
(2007/10/02)
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- Direct Oxidation of Alkanoic Acids and their Amides to γ-Lactones by Peroxydisulphate-containing Systems
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The reaction of one-electron oxidation of alkanoic acids (I) and their amides (VI) on treatment with Na2S2O8-containing systems has been studied.As a result of the direct one-pot reaction acids (I) and amides (VI) are converted into γ and δ-lactones, the reaction being regioselective and leading mainly to γ-lactones in up to 35percent yield.The regioselectivity of the oxidative lactonisation depends greatly on the nature of alkyl substituents.The results obtained are presented in terms of a mechanism suggesting the generation of acyloxyl and amidyl radicals from (I) and (VI), respectively, followed by a rearrangement via a 1,5- or 1,6-H shift into the corresponding 3- and 4-carboxy- or -carboxamido-alkyl ra The latter undergo oxidative cyclisation to produce γ and δ lactones.The system Na2S2O8-NaCl-NaOH converts carboxamides (VI) into amines with loss of one carbon atom as a result of a Hoffmann type rearrangement.
- Nikishin, Gennady I.,Svitanko, Igor V.,Troyansky, Emmanuil I.
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p. 595 - 602
(2007/10/02)
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