- Transmetallation from aluminum to tin: A facile preparation of tributylstannylprop-2-en-1-ols
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3-Substituted 3-tributylstannylprop-2-en-1-ols 2 can be efficiently prepared by hydroalumination of 3-substituted propargyl alcohols 1 with LiAlH4 and subsequent transmetallation to tin employing Bu3SnOMe instead of the commonly used Bu3SnOTf or Bu3SnCl.
- Havranek, Miroslav,Dvorak, Dalimil
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Read Online
- Synthesis of deuterated γ-linolenic acid and application for biological studies: Metabolic tuning and Raman imaging
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γ-Linolenic acid (GLA) is reported to show tumor-selective cytotoxicity through unidentified mechanisms. Here, to assess the involvement of oxidized metabolites of GLA, we synthesized several deuterated GLAs and evaluated their metabolism and cytotoxicity towards normal human fibroblast WI-38 cells and VA-13 tumor cells generated from WI-38 by transformation with SV40 virus. Deuteration of GLA suppressed both metabolism and cytotoxicity towards WI-38 cells and increased the selectivity for VA-13 cells. Fully deuterated GLA was visualized by Raman imaging, which indicated that GLA is accumulated in intracellular lipid droplets of VA-13 cells. Our results suggest the tumor-selective cytotoxicity is due to GLA itself, not its oxidized metabolites. This journal is
- Dodo, Kosuke,Sato, Ayato,Tamura, Yuki,Egoshi, Syusuke,Fujiwara, Koichi,Oonuma, Kana,Nakao, Shuhei,Terayama, Naoki,Sodeoka, Mikiko
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supporting information
p. 2180 - 2183
(2021/03/09)
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- Chemoselective Oxidation of p-Methoxybenzyl Ethers by an Electronically Tuned Nitroxyl Radical Catalyst
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The oxidation of p-methoxy benzyl (PMB) ethers was achieved using nitroxyl radical catalyst 1, which contains electron-withdrawing ester groups adjacent to the nitroxyl group. The oxidative deprotection of the PMB moieties on the hydroxy groups was observed upon treatment of 1 with 1 equiv of the co-oxidant phenyl iodonium bis(trifluoroacetate) (PIFA). The corresponding carbonyl compounds were obtained by treating the PMB-protected alcohols with 1 and an excess of PIFA.
- Hamada, Shohei,Sugimoto, Koichi,Elboray, Elghareeb E.,Kawabata, Takeo,Furuta, Takumi
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supporting information
p. 5486 - 5490
(2020/07/24)
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- Chemoselective Hydroboration of Propargylic Alcohols and Amines Using a Manganese(II) Catalyst
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The first manganese-catalyzed hydroboration of propargylic alcohols and amines as well as internal alkynes is reported. High regio- and stereoselectivity is achieved by applying 2 mol % of a manganese precatalyst based on the readily accessible bis(imino)pyridine ligand and MnCl2 as metal source. Propargylic alcohols and amines, as well as symmetric internal alkynes, were efficiently converted into the corresponding functionalized alkenes, which can serve as important and valuable intermediates for further synthetic applications such as cross-coupling reactions.
- Brzozowska, Aleksandra,Zubar, Viktoriia,Ganardi, Ruth-Christine,Rueping, Magnus
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supporting information
p. 3765 - 3769
(2020/04/15)
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- Catalyst-Free Annulation of 2-Pyridylacetates and Ynals with Molecular Oxygen: An Access to 3-Acylated Indolizines
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A catalyst and additive-free annulation of 2-pyridylacetates and ynals under molecular oxygen was the first developed, affording 3-acylated indolizines in good to excellent yields. Molecular oxygen was used as the source of the carbonyl oxygen atom in indolizines. This approach was compatible with a wide range of functional groups, and especially it has been successfully extended to unsaturated double bonds and triple bonds, which were difficult to prepare by previous methods in a single step.
- Chen, Zhengwang,Liang, Pei,Ma, Xiaoyue,Luo, Haiqing,Xu, Guohai,Liu, Tanggao,Wen, Xiaowei,Zheng, Jing,Ye, Hui
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supporting information
p. 1630 - 1639
(2019/01/26)
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- Synthesis of solandelactone F, constanolactone A and an advanced intermediate towards solandelactone e from a common synthetic intermediate
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The stereoselective synthesis of solandelactone F, constanolactone A and an advanced intermediate towards solandelactone E, from a common synthetic intermediate, is disclosed. The propargylic sulfide stereocenter is created stereoselectively via carbon-carbon bond formation in the reaction of α-chloro sulfides with alkynylzinc reagents via 1,2-asymmetric induction by a β-siloxy group. The characteristic 1,4-diol motif of the natural products is introduced by a [2,3] sigmatropic rearrangement of an allylic sulfoxide or by the Mislow-Evans-Braverman rearrangement of a propargylic sulfoxide followed by stereoselective reduction of the ensuing α,β-unsaturated ketone. Unlike earlier reports, the C11/C9 carbinol center is created with excellent stereocontrol and derivatives of natural products differing at C14/C12 can be readily obtained. Catalytic asymmetric protocols and substrate-controlled asymmetric induction are utilized for the efficient introduction of the stereogenic centers.
- Yalla, Raju,Raghavan, Sadagopan
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p. 4572 - 4592
(2019/05/16)
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- Impaired energy processing disorders and mitochondrial deficiency
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Some aspects of the invention provide for a method of treating Impaired Energy Processing Disorders and Mitochondrial Deficiencies using polyunsaturated fatty acids which are modified in certain positions to attenuate oxidative damage by Reactive Oxygen Species (ROS) and/or suppress the rate of formation of reactive products and toxic compounds.
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Page/Page column 49
(2018/09/14)
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- Enantioselective Rhodium-Catalyzed Dimerization of ω-Allenyl Carboxylic Acids: Straightforward Synthesis of C2-Symmetric Macrodiolides
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Herein, we report on the first enantioselective and atom-efficient catalytic one-step dimerization method to selectively transform ω-allenyl carboxylic acids into C2-symmetric 14- to 28-membered bismacrolactones (macrodiolides). This convenient asymmetric access serves as an attractive route towards multiple naturally occuring homodimeric macrocyclic scaffolds and demonstrates excellent efficiency to construct the complex, symmetric core structures. By utilizing a rhodium catalyst with a modified chiral cyclopentylidene-diop ligand, the desired diolides were obtained in good to high yields, high diastereoselectivity, and excellent enantioselectivity.
- Steib, Philip,Breit, Bernhard
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supporting information
p. 6572 - 6576
(2018/05/08)
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- Synthesizing method of loopworm sex pheromone and intermediate thereof
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The invention discloses a synthesizing method of loopworm sex pheromone and an intermediate thereof. The synthesizing method comprises the following steps of using propargyl alcohol and halogenated hydrocarbon as the starting raw materials, and sequential
- -
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Paragraph 0048; 0049
(2019/01/11)
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- Iridium versus Iridium: Nanocluster and Monometallic Catalysts Carrying the Same Ligand Behave Differently
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A specific secondary phosphine oxide (SPO) ligand (tert-butyl(phenyl)phosphine oxide) was employed to generate two iridium catalysts, an Ir–SPO complex and IrNPs (iridium nanoparticles) ligated with SPO ligands, which were compared mutually and with several supported iridium catalysts with the aim to establish the differences in their catalytic properties. The Ir–SPO-based catalysts showed totally different activities and selectivities in the hydrogenation of various substituted aldehydes, in which H2is likely cleaved by a metal–ligand cooperation, that is, the SPO ligand and a neighboring metal centre operate in tandem to activate the hydrogen molecule. In addition, the supported IrNPs behave very differently from both Ir–SPO catalysts. This study exemplifies perfectly the advantages and disadvantages related to the use of the main types of catalysts, and thus the dissimilarities between them.
- Cano, Israel,Martínez-Prieto, Luis M.,Chaudret, Bruno,van Leeuwen, Piet W. N. M.
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p. 1444 - 1450
(2017/02/05)
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- Stereoselective Synthesis of Exocyclic Tetrasubstituted Vinyl Halides via Ru-Catalyzed Halotropic Cycloisomerization of 1,6-Haloenynes
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Herein, a ruthenium-catalyzed cycloisomerization that transforms 1,6-haloenynes into 5-membered carbo- and heterocycles that bear exocyclic, stereodefined, tetrasubstituted vinyl halides is reported. The reaction is insensitive to air and water, tolerates a variety of functional groups, and proceeds with good to excellent stereoselectivity and yield.
- Trost, Barry M.,Kalnmals, Christopher A.
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supporting information
p. 2346 - 2349
(2017/05/12)
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- Selective Catalytic Hydrogenations of Nitriles, Ketones, and Aldehydes by Well-Defined Manganese Pincer Complexes
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Hydrogenations constitute fundamental processes in organic chemistry and allow for atom-efficient and clean functional group transformations. In fact, the selective reduction of nitriles, ketones, and aldehydes with molecular hydrogen permits access to a green synthesis of valuable amines and alcohols. Despite more than a century of developments in homogeneous and heterogeneous catalysis, efforts toward the creation of new useful and broadly applicable catalyst systems are ongoing. Recently, Earth-abundant metals have attracted significant interest in this area. In the present study, we describe for the first time specific molecular-defined manganese complexes that allow for the hydrogenation of various polar functional groups. Under optimal conditions, we achieve good functional group tolerance, and industrially important substrates, e.g., for the flavor and fragrance industry, are selectively reduced.
- Elangovan, Saravanakumar,Topf, Christoph,Fischer, Steffen,Jiao, Haijun,Spannenberg, Anke,Baumann, Wolfgang,Ludwig, Ralf,Junge, Kathrin,Beller, Matthias
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supporting information
p. 8809 - 8814
(2016/07/29)
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- Synthesis of the ω6 (5z,8z)-tetradecadienoic and (7z,10z)-hexadecadienoic polyene fatty acids
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An approach using acetylenes was used and optimized to synthesize rare natural ω6 polyene fatty acids. The key synthetic step was cross-coupling of a propargyl derivative with a terminal acetylene in the presence of equimolar amounts of Cu(I).
- Golovanov,Ganina,Groza,Eremin,Myagkova
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- Copper(i) iodide catalyzed synthesis of primary propargylic alcohols from terminal alkyne
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A highly efficient and practical method for the synthesis of primary propargylic alcohols has been developed using CuI as catalyst and paraformaldehyde as the formaldehyde source. The reaction was performed under mild reaction conditions offering the desired products in good to excellent yields with a variety of terminal alkynes.
- Kundu, Shrishnu Kumar,Mitra, Kanchan,Majee, Adinath
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p. 13220 - 13223
(2015/02/19)
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- Air-stable gold nanoparticles ligated by secondary phosphine oxides for the chemoselective hydrogenation of aldehydes: Crucial role of the ligand
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The synthesis of air-stable and homogeneous gold nanoparticles (AuNPs) employing tert-butyl(naphthalen-1-yl)phosphine oxide as supporting ligand is described via NaBH4 reduction of a Au(I) precursor, [(tert-butyl(naphthalen-1-yl)phosphine oxide)AuCl]2. This highly reproducible and simple procedure furnishes small (1.24 ± 0.16 nm), highly soluble nanoparticles that are found to be highly active catalysts for the hydrogenation of substituted aldehydes, giving high conversions and chemoselectivities for a wide variety of substrates. In addition to catalytic studies the role of the novel stabilizer in the remarkable activity and selectivity exhibited by this system was interrogated thoroughly using a wide range of techniques, including ATR FT-IR, HRMAS NMR, XPS, and EDX spectroscopy. In particular, isotopic labeling experiments enabled us to probe the coordination mode adopted by the SPO ligand bound to the nanoparticle surface by ATR FT-IR spectroscopy. In combination with a series of control experiments we speculate that the SPO ligand demonstrates ligand-metal cooperative effects and plays a seminal role in the heterolytic hydrogenation mechanism.
- Cano, Israel,Chapman, Andrew M.,Urakawa, Atsushi,Van Leeuwen, Piet W. N. M.
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supporting information
p. 2520 - 2528
(2014/03/21)
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- Investigating inner-sphere reorganization via secondary kinetic isotope effects in the C-H cleavage reaction catalyzed by soybean lipoxygenase: Tunneling in the substrate backbone as well as the transferred hydrogen
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This work describes the application of NMR to the measurement of secondary deuterium (2° 2H) and carbon-13 (13C) kinetic isotope effects (KIEs) at positions 9-13 within the substrate linoleic acid (LA) of soybean lipoxygenase-1. The KIEs have been measured using LA labeled with either protium (11,11- h2-LA) or deuterium (11,11-d2-LA) at the reactive C11 position, which has been previously shown to yield a primary deuterium isotope effect of ca. 80. The conditions of measurement yield the intrinsic 2° 2H and 13C KIEs on kcat/Km directly for 11,11-d2-LA, whereas the values for the 2° 2H KIEs for 11,11-h2-LA are obtained after correction for a kinetic commitment. The pattern of the resulting 2° 2H and 13C isotope effects reveals values that lie far above those predicted from changes in local force constants. Additionally, many of the experimental values cannot be modeled by electronic effects, torsional strain, or the simple inclusion of a tunneling correction to the rate. Although previous studies have shown the importance of extensive tunneling for cleavage of the primary hydrogen at C11 of LA, the present findings can only be interpreted by extending the conclusion of nonclassical behavior to the secondary hydrogens and carbons that flank the position undergoing C-H bond cleavage. A quantum mechanical method introduced by Buhks et al. [J. Phys. Chem. 1981, 85, 3763] to model the inner-sphere reorganization that accompanies electron transfer has been shown to be able to reproduce the scale of the 2° 2H KIEs.
- Meyer, Matthew P.,Klinman, Judith P.
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supporting information; experimental part
p. 430 - 439
(2011/04/16)
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- Gold(l)-catalyzed formation of furans by a Claisen type rearrangement of ynenyl allyl ethers
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A series of ynenyl allyl ethers were rearranged into polysubstituted furans in the presence of a gold(I) catalyst. It is proposed that the transformation involves a Claisen-type rearrangement that allows the efficient creation of quaternary centers under mild experimental conditions.
- Istrate, Florin M.,Gagosz, Fabien
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supporting information; experimental part
p. 878 - 885
(2011/09/20)
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- Synthesis of linoleic acids combinatorially labeled at the vinylic positions as substrates for lipoxygenases
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Mammalian lipoxygenases have been implicated in a number of inflammation-related human diseases. Soybean lipoxygenase-1 is the archetypical example of known lipoxygenases. Here we report the synthesis of linoleic acid and (11,11)-d2-linoleic acid which are combinatorially labeled at the vinylic positions (9, 10, 12, and 13). Combinatorial labeling schemes allow for the simultaneous determination of KIEs in enzymatic reactions using NMR. Substrates are, thus, available as probes of detailed mechanism in kinetic isotope effect (KIE) studies of lipoxygenases.
- Meyer, Matthew P.,Klinman, Judith P.
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p. 3600 - 3603
(2008/09/19)
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- Synthesis of (4R,15R,16R,21S)-rollicosin and its 4S epimer
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(4R,15R,16R,21S)-Rollicosin (2) was synthesized by palladium-catalyzed coupling of two building blocks 4 and 5. Lactone 4 was synthesized from 1-heptyne and terminal acetylene 5 was prepared from lactone 6 and allyl iodide or (S)-epichlorohydrin. (4S,15R,16R,21S)-Rollicosin (3) was also synthesized from (R)-epichlorohydrin by the same synthetic pathway. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Wu, Ming-Jung,Lee, Cheng-Lin,Wu, Yang-Chang,Chen, Chiao-Pei
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experimental part
p. 854 - 861
(2009/04/11)
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- Synthesis of functionalized furans via gold(I)-catalyzed Claisen-type rearrangement
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(Chemical Equation Presented) Gold(I)-catalyzed cyclization of pentenynyl allyl ethers allows the rapid construction of functionalized furans. The concerted oxy-Claisen-type mechanism induces a complete selectivity of the process and allows the easy forma
- Istrate, Florin M.,Gagosz, Fabien L.
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p. 730 - 733
(2008/09/17)
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- Titanocene-catalyzed regiodivergent epoxide openings
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The first regiodivergent opening of unbiased epoxides providing the ring-opened products in high enantiomeric excess from racemic and exceptionally high enantiomeric excess from enantioenriched substrates in a double asymmetric process has been devised. It constitutes a more general case of the very important enantioselective openings of meso-epoxides. Copyright
- Gansaeuer, Andreas,Fan, Chun-An,Keller, Florian,Keil, Jutta
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p. 3484 - 3485
(2008/01/01)
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- Concise synthesis of (8Z,11Z,14Z)-8,11,14-heptadecatrienal, (7Z,10Z,13Z)-7,10,13-hexadecatrienal, and (8Z,11Z)-8,11-heptadecadienal, components of the essential oil of marine green alga Ulva pertusa
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The long-chain aldehydes, (8Z,11Z,14Z)-8,11,14-heptadecatrienal, (7Z,10Z,13Z)-7,10,13-hexadecatrienal, and (8Z,11Z)-8,11-heptadecadienal, were concisely synthesized by using Grignard coupling, catalytic hydrogenation with the Lindlar catalyst, and oxidation with Dess-Martin periodinane as the key steps. Particularly, (8Z,11Z,14Z)-8,11,14-heptadecatrienal and (7Z,10Z, 13Z)-7,10,13-hexadecatrienal both possessed a seaweed-like odor.
- Akakabe, Yoshihiko,Washizu, Kensuke,Matsui, Kenji,Kajiwara, Tadahiko
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p. 1348 - 1352
(2008/02/01)
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- Synthesis of diastereomerically and enantiomerically pure 2,3-disubstituted tetrahydrofurans using a sulfoxonium ylide
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Nucleophilic substitution reactions of 2,3-epoxy alcohols, easily prepared via Sharpless asymmetric epoxidation chemistry, offer access to a wide variety of enantiomerically pure compounds. In this communication, we describe the use of a Payne rearrangement to control regioselectivity in the ring-opening of a series of 2,3-epoxy alcohols with dimethylsulfoxonium methylide to yield diastereomerically and/or enantiomerically pure disubstituted tetrahydrofuran rings. The factors influencing the success and substitution pattern of the THF ring products are discussed, including steric, electronic, and solvent effects. Copyright
- Schomaker, Jennifer M.,Pulgam, Veera Reddy,Borhan, Babak
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p. 13600 - 13601
(2007/10/03)
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- Electrotelluration: A new approach to tri- and tetrasubstituted alkenes
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A novel electrotelluration process is described in which a Michael addition of an alkyl or aryl tellurolate anion occurs onto an activated alkyne with subsequent trapping of a vinyl anion with electrophiles (aldehydes and ketones) other than a proton. This process provides an efficient regio-and stereospecific route to tri- and tetrasubstituted alkenes. Methodologically significant examples of this chemistry were studied in which aryl and alkyl tellurolate anions were added to ω-keto alkynyl esters in a Michael reaction, and the incipient vinyl anions were trapped intramolecularly by the internal aldehydes. The reactive centers were tethered by different lengths of alkyl chains to form highly functionalized five-, six-, seven-, and eight-membered rings in modest to good yields.
- Marino, Joseph P.,Nguyen, Hanh Nho
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p. 6291 - 6296
(2007/10/03)
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- Ring scission of diastereomeric 4-butylspiropentylcarbinyl radicals as a chemical model for identifying enzyme-catalyzed FAD adducts resulting from spiropentylacetyl-CoA
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Both diastereomeric 4-butylspiropentylcarbinyl bromides (14a and 14b) were synthesized in seven steps starting from 1-heptyne, and the stereochemical assignments based upon NOE experiments were confirmed by converting their immediate alcohol precursors (13a and 13b) to 1,4-dibutylspiropentanes (17a and 17b) with C1 and C2 symmetry. Each bromide was used to generate its corresponding spiropentylcarbinyl radical (18a and 18b) via its AIBN-initiated tri-n-butyltin hydride reduction. The radical-trapped products are identified, the preferred ring scission mode is identified (C1-C2 bond cleavage), and the estimated rates for the ring opening of 4-butylspiropentylcarbinyl radical (18, k25 °C ≥ ~ 5 × 109 s-1) and 2-butyl-1-vinylcyclopropylcarbinyl radical (33, k25 °C ~ 5 × 108 s-1) are reported. High-level ab initio calculations addressing the ring-opening isomerizations of cyclopropylcarbinyl and spiropentylcarbinyl radicals also are presented. These results in conjunction with a previous study enable us to propose two structures for the enzyme-catalyzed FAD adducts resulting from spiropentylacetic acid-CoA, a synthetic byproduct of fatty acid metabolism.
- Lis, Lev,Koltun, Elena S.,Liu, Hung-Wen,Kass, Steven R.
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p. 1276 - 1287
(2007/10/03)
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- Selective reduction of aldehydes via BINOL-Zr complex
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An easily assembled catalyst from (±)-BINOL (1,1′-bi-naphthol) and Zr(OiPr)4·iPrOH selectively reduces aldehydes at room temperature. Ketones remain intact under these conditions. A catalytic amount of BINOL-Zr complex in the presence of 2-propanol also effectively reduces a variety of chiral and achiral aldehydes.
- Lorca, Miguel,Kuhn, Dan,Kurosu, Michio
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p. 6243 - 6246
(2007/10/03)
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- Design and synthesis of useful intermediates for novel lipoxygenase substrates through enzymatic resolution
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Unnatural lipoxygenase substrates carrying spacing modifiers with a non-ionic hydroxy terminus and with methylene (flanked by the cis,cis diene moiety) pro-(S)-hydrogen can be synthesized from the intermediates 1a-1c. These intermediates are conveniently synthesized via enzymatic resolution with lipase in organic solvents.
- Yadav,Nanda,Rao, A. Bhaskar
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- Synthesis of polyacetylenic acids isolated from Heisteria acuminata
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matrix presented Four linear polyacetylenic compounds were synthesized. Pentadeca-6,8,10-triynoic acid 1 and octadeca-8,10,12-triynoic acid 2 were synthesized by using acetylene coupling reactions. The syntheses of (Z)-hexadec-11-en-7,9-diynoic acid 3 and (Z)-octadec-12-en-7,9-diynoic acid 4 by using vinylic telluride coupling reactions were accomplished.
- Zeni, Gilson,Panatieri, Rodrigo B.,Lissner, Eliseo,Menezes, Paulo H.,Braga, Antonio L.,Stefani, Helio A.
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p. 819 - 820
(2007/10/03)
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- Total syntheses of (-)-grandinolide and (-)-sapranthin by the sharpless asymmetric dihydroxylation of methyl trans-3-pentenoate: Elucidation of the stereostructure of (-)-sapranthin
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Methyl trans-3-pentenoate (7) was converted into the cis-substituted γ- lactone 8 in a single step with 78% ee. The derived enolate dilithio-8 was alkylated trans-selectively with primary iodoalkanes with 1-iodobutane dilithio-8 afforded, after esterification with isovaleroyl chloride, the epi- blastmycinone 9. Dilithio-8 gave (-)-grandinolide (II) with 1-iodo-19- phenylnonadecane (20). A third trans-selective alkylation of dilithio-8 was undertaken with 16-iodo-1,5-hexadecadiene-7,9-diyne (21). This gave the γ- 1actone 12, which had the published relative configuration of (-)-sapranthin but different spectroscopic data. When the OH group of lactone 8 was inverted (to hydroxylactone 40) and the derived enolate dilithio-40 alkylated with iodide 21, lactone 41 resulted. Its 1H and 13C NMR spectra and the sign and value of optical rotation coincide with the data of natural sapranthin. These findings establish that (-)-sapranthin possesses the relative and absolute configuration of stereoformula 41. The synthesis of iodide 21 was performed via the dienoic carboxylic ester trans-23 which stemmed from the Claisen-Ireland rearrangement (27 → 28/29)/esterification (28/29 → 26)/Cope rearrangement (26 → 23) sequence shown in Scheme 5.
- Harcken, Christian,Brueckner, Reinhard,Rank, Elisabeth
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p. 2342 - 2352
(2007/10/03)
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- Acid-mediated conversion of methylene-interrupted bisepoxides to tetrahydrofurans: A biomimetic transformation
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The acid-mediated transformation of syn and anti methylene interrupted cis,cis and cis,trans bisepoxides to tetrahydrofurans is high yielding, and demonstrates both regioselectivity and stereoselectivity. Trans,trans methylene interrupted bisepoxides do not yield tetrahydrofurans under the same conditions.
- Capon, Robert J.,Barrow, Russell A.
-
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- Insect pheromones and their analogs LV. Synthesis of trideca-4E,7Z-dien-1-yl acetate - Component of the sex pheromone of Phthorimaea opercucella
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Starting from propargyl alcohol and using the thermal Claisen rearrangement at the stage of constructing the (E)-double bond, we have synthesized trideca-4E, 7Z-dien-1-yl acetate - a component of the sex pheromone of the potato moth Phthorimaea opercucella (Zeller).
- Odinokov,Vakhidov,Shakhmaev,Zorin
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p. 350 - 352
(2007/10/03)
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- An expeditious synthesis of alk-2-yn-1-ols
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A convenient inexpensive preparation of alk-2-yn-1-ols, commencing from terminal alkynes, has been developed. This procedure allows for using paraformaldehyde instead of gaseous formaldehyde for hydroxymethylation of alk-1-ynylmagnesium bromides.
- Zwierzak, Andrzej,Tomassy, Beata
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p. 3593 - 3600
(2007/10/03)
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- EXO- AND ENDOHORMONES, XVI SYNTHESIS OF (4E, 7Z)-4,7-TRIDECADIEN 1-YL ACETATE, THE SEX PHEROMONE FOR THE LEAFMINER LITHOCOLLETIS CORYLIFOLIELLA
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The synthesis of the sex pheromone of the leafminer moth, Lithocolletis corylifoliella, (4E, 7Z)-4,7-tridecadien-1-yl acetate, was based on a C5+C8 scheme.The coupling reaction took place between the Grignard reagent of 4-pentin-1-1-oic acid and 1-bromo-2Z-octene.Propargylic alcohol was used as a starting material in order to obtain the two synthons.
- Gocan, Alexandra,Gansca, Lucia,Oprean, Ioan
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p. 253 - 258
(2007/10/03)
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- Enzymatic Hydrolysis of Alken- and Alkyn-3-ol Acetates in an Acetone-Water Solvent System: Effect of Unsaturation on the Enantioselectivity of Pseudomonas cepacia Lipase-catalyzed Hydrolysis
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High enentioselectivity was observed for the Pseudomonas cepacia lipase-catalyzed hydrolysis of (E)-allylic acetate 1 and propargylic acetate 2 in an acetone-water solvent system, while (E)-homoallylic acetate 3 and homopropargylic acetate 4 gave poor enantioselectivity.
- Kamezawa, Makoto,Raku, Takao,Tachibana, Hojun,Ohtani, Takehiko,Naoshima, Yoshinobu
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p. 549 - 551
(2007/10/02)
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- Stereoselective Synthesis of 1,4-Dienes. Application to the Preparation of Insect Pheromones (3Z,6Z)-Dodeca-3,6-dien-1-ol and (4E,7Z)-Trideca-4,7-dienyl Acetate
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Stereoselective synthesis of Z,E- and Z,Z-1,4-dienes has been achieved by the cross-coupling of allylic substrates with vinyl organometallic reagents.Key to this strategy was the development of a method for regiospecific incorporation of a tri-n-butylstannyl group in the γ-position of the allylic cross-coupling partner.The steric bulk of this moiety ensures the stereochemical integrity of the allylic double bond throughout the coupling sequence and is easily replaced by hydrogen in the coupled product.This strategy has been applied to the synthesis of the termite trail marker pheromone 22 and the leafminer moth sex pheromone 28.
- Hutzinger, Michael W.,Oehlschlager, Allan C.
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p. 4595 - 4601
(2007/10/02)
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- General synthesis of 2-alkyn-1-ylboronates in excellent isomeric purity
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2-Alkyn-1-ylboronates have been synthesized successfully, in excellent isomeric purity, via the in situ homologation of alkyn-1-ylboronates with LiCH2I. The relative reactivities exhibited by various LiCH2X reagents (X = Cl; Br; I) are described.
- Soundararajan, Raman,Li, Guisheng,Brown, Herbert C.
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p. 8961 - 8964
(2007/10/02)
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- Total Synthesis of Solamin and Reticulatin
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A total synthesis of the natural products, solamin 1 and reticulatin 2 is described.The monotetrahydrofuran moiety 12a of compounds 1 and 2 was constructed by an eight-step reaction sequence, starting from (-)-muricatacin 5, an acetogenin derivative.The γ
- Makabe, Hidefumi,Tanaka, Akira,Oritani, Takayuki
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p. 1975 - 1982
(2007/10/02)
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- The Synthesis and Absolute Configuration of the Novel Ichthyotoxic Diacylglycerols, Umbraculumin A and Umbraculumin C
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The total syntheses of umbraculumin A 1 and umbraculumin C 2 in homochiral form are described.Noteworthy steps involve (i) the preparation of the key Z,E-acid 10 by organolithium addition to pyrylium salts, (ii) the use of the 4-methoxyphenylmethyl protecting group for the preparation of 1,2-diacyl glycerols and its removal using trifluoroacetic acid-anisole without significant acyl migration (DDQ removal having proved inefficient) and (iii) a new procedure for the stereoselective preparation of (Z)- and (E)-3-methylthiopropenoic acid.
- Medeiros, Edna Faria De,Herbert, John M.,Taylor, Richard J. K.
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p. 2725 - 2730
(2007/10/02)
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- An Isotopic Study (2H and 18O) of the Enzymatic Conversion of Linoleic Acid into Colneleic Acid with Carbon Chain Fracture: the Origin of Shorter Chain Aldehydes
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Contrary to earlier reports, the divinyl 9-ether oxygen of colneleic acid is shown by experiment with 18O2 to originate from oxygen, not water.Using -9(S)-hydroperoxyoctadeca-10(E),12(Z)-dienoic acid, made enzymatically from synthetic linoleic acid, it is found that the distribution of deuterium as determined by NMR and mass spectrometry in the fractured carbon chain of colneic acid formed by potato enzyme, is consistent with the intervention of an epoxy carbonium ion intermediate.Though divinyl acids such as colneleic and colnelenic acid give the expected shorter chain aldehydes on treatment with aqueous acid, it is likely that the latter are formed in most plants by trapping of a monovinyl oxonium ion rather than by rehydration of colneleic and colnelenic acid.
- Crombie, Leslie,Morgan, David O.,Smith, Elisabeth H.
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p. 567 - 575
(2007/10/02)
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- THE SYNTHESIS AND ABSOLUTE CONFIGURATION OF THE NOVEL ICHTHYOTOXIC DIACYLGLYCEROL, UMBRACULUMIN A
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A total synthesis of umbraculumin A (1) in homochiral form is described.
- Medeiros, Edna Faria De,Herbert, John M.,Taylor, Richard J. K.
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p. 5843 - 5844
(2007/10/02)
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- 2,5,6,7-tetranor-18,18,19,19-tetradehydro-4,8-inter-m-phenylene PGI2 derivatives
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Disclosed herein are novel prostaglandin I2 (PGI2) derivatives exhibiting excellent physiological activities, said derivatives being represented by the general formula: STR1 wherein R1, R2 and R3 are as defined herein.
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- A STEREOSELECTIVE SYNTHESIS OF PEAR ESTER VIA ARSENIC YLIDE
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The paper describes a four-step synthesis of ethyl (2E,4Z)-2,4-decadienoate (pear ester) from propargyl alcohol with a 50percent total yield.It also gives the synthesis of ethyl (2E,4E)-2,4-decadienoate.In both cases arsenic ylides were used to give the satisfactory results.
- Zhengming, Li,Tiansheng, Wang,Diankun, Zhang,Zhengheng, Gao
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- 2,5,6,7-tetranor-4,8-inter-m-phenylene PGI2 derivatives
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Disclosed herein are novel prostaglandin I2 (PGI2) derivatives exhibiting excellent in vivo duration and activities, said derivatives being represented by the general formula: STR1 wherein R1, X, R2 and R3 are as defined herein.
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- The Preparation of Some Octenyl Sulfides from Oct-1-en-3-ol and Oct-2-en-1-ol
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(E)- and (Z)-1-(Phenylthio)oct-2-ene, (E)-1-(methylthio)- and 1-(t-butylthio)-oct-2-ene, S- N,N-dimethylthiocarbamate, S- N,N-dimethylthiocarbamate, (E)-(oct-2-enylthio)benzothiazole, and S- N,N,N',N'-tetramethylphosphorodiamidothioate have been prepared by nucleophilic substitution reactions and - and -sigmatropic shifts involving intermediates prepared from oct-1-en-3-ol and (E)- and (Z)-oct-2-en-1-ol.
- Binns, Malcolm R.,Haynes, Richard K.,Lambert, Dale E.,Schober, Paul A.,Turner, Susan G.
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p. 281 - 290
(2007/10/02)
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- STEREOCONTROLLED TOTAL SYNTHESIS OF THE MACROCYCLIC LACTONE (-)-ASPICILIN
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The essential features of the enantiocontrolled total synthesis of (-)-aspicilin are the strategic use of the photochemical rearrangement of α,β-epoxy diazomethyl ketones to 4-hydroxyalkenoates (Scheme 1) and the stereochemical control of the Sharpless epoxidation, α,ο functionalization of an alkynol using potassium 3-aminopropylamine (KAPA) as acetylene zipper, coupling between C7 and C8 by means of a Wittig reaction and lactonization by using 2,6-dichlorobenzoyl chloride.
- Waanders, P.P.,Thijs, L.,Zwanenburg, B.
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p. 2409 - 2412
(2007/10/02)
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- Synthesis of the optical antipodes of 4-alkyl-γ-lactones
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Optical antipodes of 4-alkyl-γ-lactones 3 have been prepared by photochemical rearrangement of optically active α,β-epoxy diazomethyl ketones 1 in ethanol to give 4-hydroxy-alkenoates 2, followed by reduction of the alkene bond and subsequent lactonization.The required epoxy diazomethyl ketones 1 were obtained via the following sequence of reactions: alkylation of 2-propyn-1-ol, subsequent reduction to the alkenols 6, Sharpless epoxidation to 2,3-epoxy alcohols 7, oxidation to glycidic esters 8 and finally conversion to diazo ketones 1.The enantiomeric purities range from 84 to 100percent.
- Thijs, Lambertus,Waanders, Peter P.,Stokkingreef, Edwin H. M.,Zwanenburg, Binne
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p. 332 - 337
(2007/10/02)
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- General Synthesis of Polyunsaturated Fatty Acid Hydroperoxides Involving a Novel Vinylcyclopropyl Bromide Ring Opening
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A variety of 18- and 20-carbon polyunsaturated fatty acid hydroperoxides were synthesized via an orbital symmetry controlled ring opening of vinylcyclopropyl bromides.Six 20-carbon vinylcyclopropyl bromides (20-25) were synthesized by a route starting from 2-ethoxy-Δ3,5-dihydropyran (3) and an 18-carbon vinylcyclopropyl bromide by a route starting from propargyl alcohol.All six vinylcyclopropyl bromides underwent facile Ag+-asisted ring opening in the presence of excess H2O2 to form the target fatty acid hydroperoxide isomers in good yields.In most cases the products were produced with stereochemical control.The product hydroperoxides formed in this ring-opening reaction are consistent with a mechanism involving the formation of a pentadienyl cation intermediate.A minor product found in the reaction of vinylcyclopropyl bromide 26 provides evidence that homoallylic participation by alkenyl substituents can change the course of the electrocyclic ring opening.
- Porter, N. A.,Ziegler, C. B.,Khouri, F. F.,Roberts, D. H.
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p. 2252 - 2258
(2007/10/02)
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