- Modular Total Synthesis of iso-Archazolids and Archazologs
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Full details on the design, development, and successful implementation of suitable synthetic strategies directed toward the total synthesis of iso-archazolids and archazologs are reported. Both a biomimetic and a multistep total synthesis of iso-archazolid B, the most potent and least abundant archazolid, are described. The bioinspired conversion from archazolid B was realized by a high-yielding 1,8-Diazabicyclo[5.4.0]undec-7-ene catalyzed one-step double-bond shift. A highly stereoselective total synthesis was accomplished in 25 steps, involving a sequence of highly stereoselective aldol reactions, an efficient aldol condensation to forge two elaborate fragments, and a challenging ring-closing metathesis macrocyclization with an unusual Stewart-Grubbs catalyst. These strategies proved to be generally useful and could be successfully implemented for the preparation of three novel iso-archazolids as well as five novel archazologs, lacking the thiazole side chain. A wide variety of further archazolids and archazologs may now be targeted for exploration of the promising anticancer potential of these polyketide macrolides.
- Dedenbach, Simon,Menche, Dirk,Rivière, Solenne,Ruiz, Johal,Scheeff, Stephan
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p. 10190 - 10223
(2021/08/16)
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- Fluorinated Musk Fragrances: The CF2Group as a Conformational Bias Influencing the Odour of Civetone and (R)-Muscone
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The difluoromethylene (CF2) group has a strong tendency to adopt corner over edge locations in aliphatic macrocycles. In this study, the CF2group has been introduced into musk relevant macrocyclic ketones. Nine civetone and five muscone analogues have been prepared by synthesis for structure and odour comparisons. X-ray studies indeed show that the CF2groups influence ring structure and they give some insight into the preferred ring conformations, triggering a musk odour as determined in a professional perfumery environment. The historical conformational model of Bersuker and co-workers for musk fragrance generally holds, and structures that become distorted from this consensus, by the particular placement of the CF2groups, lose their musk fragrance and become less pleasant.
- Callejo, Ricardo,Corr, Michael J.,Yang, Mingyan,Wang, Mingan,Cordes, David B.,Slawin, Alexandra M. Z.,O'Hagan, David
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p. 8137 - 8151
(2016/06/13)
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- METHOD FOR PRODUCING 7-OCTENAL
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Provided is a method for highly selectively producing 7-octenal with a high conversion ratio through the isomerization reaction of 2,7-octadiene-1-ol. Specifically, provided is a method for producing 7-octenal, in which a copper-based catalyst is obtained by reducing a copper-based catalyst precursor described below, and an isomerization reaction of 2,7-octadiene-1-ol is caused in a gas phase using a fixed-bed reaction in the presence of the obtained copper-based catalyst. The copper-based catalyst precursor: a copper-based catalyst precursor obtained by calcining a mixture containing copper, iron, aluminum, and calcium silicate in which an atomic ratio of iron and aluminum to copper [(Fe+Al)/Cu] is in a range of 1.71 to 2.5, an atomic ratio of aluminum to iron [Al/Fe] is in a range of 0.001 to 3.3, and calcium silicate is contained in a range of 15% by mass to 65% by mass at a temperature in a range of 500°C to 1,000°C.
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-
Paragraph 0130; 0131; 0132; 0172; 0173; 0174; 0175
(2015/07/22)
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- The difluoromethylene (CF2) group in aliphatic chains: Synthesis and conformational preference of palmitic acids and nonadecane containing CF2 groups
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The syntheses of palmitic acids and a nonadecane are reported with CF 2 groups located 1,3 or 1,4 to each other along the aliphatic chain. Specifically 8,8,10,10- and 8,8,11,11-tetrafluorohexadecanoic acids (6b and 6c) are prepared as well as the singly modified analogue 8,8-difluorohexadecanoic acid (6a). Also 8,8,11,11-tetrafluorononadecane (27) is prepared as a pure hydrocarbon containing a 1,4-di-CF2 motif. The modified palmitic acids are characterized by differential scanning calorimetry (DSC) to determine melting points and phase behaviour relative to palmitic acid (62.5 °C). It emerges that 6c, with the CF2 groups placed 1,4- to each other, has a significantly higher melting point (89.9 °C) when compared to the other analogues and palmitic acid itself. It is a crystalline compound and the structure reveals an extended anti-zig-zag chain. Similarly 8,8,11,11- tetrafluorononadecane (27) adopts an extended anti-zig-zag structure. This is rationalized by dipolar relaxation between the two CF2 groups placed 1,4 to each other in the extended anti-zig-zag chain and suggests a design modification for long chain aliphatics which can introduce conformational stability.
- Wang, Yi,Callejo, Ricardo,Slawin, Alexandra M.Z.,O'Hagan, David
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supporting information
p. 18 - 25
(2014/01/23)
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- A relay ring-opening/double ring-closing metathesis strategy for the bicyclic macrolide-butenolide core structures
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A concise strategy has been developed for the synthesis of the bicyclic macrolide-butenolide core structures of various natural products with the macrolide ring size ranging from 12- to 16-membered. The bicyclic structure was easily assembled using the relay ring-opening/double ring-closing metathesis strategy. An efficient synthesis of (±)-desmethyl manshurolide has been achieved as an application of this strategy. This journal is
- Halle, Mahesh B.,Fernandes, Rodney A.
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p. 63342 - 63348
(2015/02/19)
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- METHOD FOR PRODUCING HIGH PURITY TERMINAL OLEFIN COMPOUND
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An industrially advantageous method for producing a high purity terminal olefin is disclosed, comprising the steps of (a) contacting a mixture comprising a terminal olefin represented by formula (1): and one or more corresponding internal olefins as impurities, with a brominating agent in the presence of water or an alcohol, to convert the internal olefin(s) to compound(s) having a higher boiling point than the terminal olefin; and (b) purifying the terminal olefin by distillation from the reaction mixture.
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Page/Page column 4
(2012/02/06)
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- A tandem 1,3-H-shift-6π-electrocyclization-cyclic 2-amido-diene intramolecular Diels-Alder cycloaddition approach to BCD-ring of atropurpuran
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An approach toward the BCD-ring of atropurpuran via a sequence of allenic 1,3-H shift, 6π-electron pericyclic ring closure, and intramolecular Diels-Alder cycloaddition of cyclic 2-amidodiene is described.
- Hayashi, Ryuji,Ma, Zhi-Xiong,Hsung, Richard P.
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supporting information; scheme or table
p. 252 - 255
(2012/03/08)
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- METHOD FOR PRODUCING CARBONYL COMPOUND AN PRO-OXIDANT USED FOR PRODUCTION OF CARBONYL COMPOUND
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The invention provides a process for the preparation of a carbonyl compound in high efficiency by oxidizing an alcohol. The process for the preparation of a carbonyl compound of the present invention includes a step of oxidizing an alcohol in the presence of a compound of the formula (I) or a derivative or a salt thereof, and an oxidant, wherein R1 and R2 independently represent hydrogen, a halogen, a nitro or acidic group, or an alkyl or alkoxy group, each of which optionally has a substituent, or R1 and R2 combine the two carbon atoms to which they are boned to form an aromatic ring.
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Page/Page column 12; 14-15
(2009/08/16)
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- Combination of RCM and the Pauson-Khand reaction: One-step synthesis of tricyclic structures
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The combination of ring-closing metathesis (RCM) followed by an intramolecular Pauson-Khand reaction gives direct entry to tricyclic compounds. The RCM was carried out on a hexacarbonylcobalt-complexed alkyne, this complex acting as a protecting group against enyne metathesis. The procedure was studied for dienynes containing heteroatoms and allows the building of [6,5,5] and [7,5,5] tricyclic systems. The feasibility of the process depends strongly on the nature of the substrate. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Rosillo, Marta,Arnaiz, Eduardo,Abdi, Delbrin,Blanco-Urgoiti, Jaime,Dominguez, Gema,Perez-Castells, Javier
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experimental part
p. 3917 - 3927
(2009/04/07)
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- Novel potent macrocyclic inhibitors of the hepatitis C virus NS3 protease: Use of cyclopentane and cyclopentene P2-motifs
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Several highly potent novel HCV NS3 protease inhibitors have been developed from two inhibitor series containing either a P2 trisubstituted macrocyclic cyclopentane- or a P2 cyclopentene dicarboxylic acid moiety as surrogates for the widely used N-acyl-(4R)-hydroxyproline in the P2 position. These inhibitors were optimized for anti HCV activities through examination of different ring sizes in the macrocyclic systems and further by exploring the effect of P4 substituent removal on potency. The target molecules were synthesized from readily available starting materials, furnishing the inhibitor compounds in good overall yields. It was found that the 14-membered ring system was the most potent in these two series and that the corresponding 13-, 15-, and 16-membered macrocyclic rings delivered less potent inhibitors. Moreover, the corresponding P1 acylsulfonamides had superior potencies over the corresponding P1 carboxylic acids. It is noteworthy that it has been possible to develop highly potent HCV protease inhibitors that altogether lack the P4 substituent. Thus the most potent inhibitor described in this work, inhibitor 20, displays a Ki value of 0.41 nM and an EC50 value of 9 nM in the subgenomic HCV replicon cell model on genotype 1b. To the best of our knowledge this is the first example described in the literature of a HCV protease inhibitor displaying high potency in the replicon assay and lacking the P4 substituent, a finding which should facilitate the development of orally active small molecule inhibitors against the HCV protease.
- Baeck, Marcus,Johansson, Per-Ola,Wangsell, Fredrik,Thorstensson, Fredrik,Kvarnstroem, Ingemar,Ayesa, Susana,Waehling, Horst,Pelcman, Mikael,Jansson, Katarina,Lindstroem, Stefan,Wallberg, Hans,Classon, Bjoern,Rydergard, Christina,Vrang, Lotta,Hamelink, Elizabeth,Hallberg, Anders,Rosenquist, Asa,Samuelsson, Bertil
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p. 7184 - 7202
(2008/09/17)
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- Tishchenko reactions of aldehydes promoted by diisobutylaluminum hydride and its application to the macrocyclic lactone formation
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Aliphatic aldehydes react with catalytic amount of Dibal-H in n-pentane to give the corresponding Tishchenko products in good to excellent yields. On contrary, α-silyloxy aldehydes give α-silyloxy ketones via Oppenauer oxidation under similar condition. Tishchenko reaction of ω-alkene aldehydes followed by RCM and hydrogenation affords a convenient method to prepare the 11-37 membered macrocyclic lactones.
- Hon, Yung-Son,Wong, Ying-Chieh,Chang, Chun-Ping,Hsieh, Cheng-Han
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p. 11325 - 11340
(2008/03/12)
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- A tandem aza-claisen rearrangement and ring closing metathesis reaction for the synthesis of cyclic allylic trichloroacetamides
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(Chemical Equation Presented) A one-pot tandem palladium(II)-catalyzed aza-Claisen rearrangement and ring closing metathesis process has been developed for the efficient synthesis of cyclic allylic trichloroacetamides. The use of chiral Pd(II) catalysts such as (S)-COP-Cl during the rearrangement stage results in the preparation of these compounds in excellent yields and in high enantiomeric excess.
- Swift, Michael D.,Sutherland, Andrew
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p. 5239 - 5242
(2008/09/17)
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- Synthesis of (+)-Sch 642305 by a biomimetic transannular Michael reaction
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The synthesis of (+)-Sch 642305 (1) has been completed in 17 steps in 1.6% overall yield. Transannular Michael reaction of 2b with NaH in THF provided cyclohexenone 23 stereospecifically. Heating 23 in TFA/CDCI3 provided a 3:1 equilibrium mixture of 23 and 25, which was hydrolyzed to give (+)-6-epi-Sch 642305 (24) and (+)-Sch 642305 (1), respectively.
- Snider, Barry B.,Zhou, Jingye
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p. 1283 - 1286
(2007/10/03)
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- Liquid-phase isomerization of saturated and unsaturated epoxides
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The liquid-phase isomerization of a variety of epoxides was studied using a complex catalyst system based on magnesium bromide and dimethylformamide. The data obtained elucidate the mechanism of the liquid-phase isomerization and show the range of oxygen-containing compounds which can be prepared through this reaction.
- Mel'nik,Khvatova,Moskvichev,Srednev,Egorova
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p. 167 - 169
(2007/10/03)
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- Isomerization of Cyclooctene and Cyclododecene Oxides Catalyzed by Solid Acids and Bases
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The title reactions were carried out over seven catalysts.From cyclooctene oxide a large amount of 7-octenal was formed together with 3-cycloocten-1-ol over SiO2-Al2O3 and SiO2-TiO2, 3-cycloocten-1-ol over solid H3PO4, and cyclooctanone over FeSO4.Most catalysts except for NiSO4, Al2O3, and Tio2-ZrO2 produced 1,3-cyclododecadiene, cyclododecanone, and 2-cyclododecen-1-ol uniformly from cyclododecene oxide.Allylic alcohols were preferentially given by Al2O3 and TiO2-ZrO2.
- Arata, Kazushi,Nakamura, Hideo,Nakamura, Yuki
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p. 2351 - 2353
(2007/10/02)
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- POLYACETYLENES FROM THE ROOTS OF PANAX GINSENG
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Key Word Index - Panax ginseng; Araliaceae; polyacetylene; ginsenoyne A; ginsenoyne B; ginsenoyne C; ginsenoyne D; ginsenoyne E. Abstract - Five new polyacetylenes named ginsenoynes A, B, C, D and E were isolated from the hexane extract of the root of Panax ginseng.These structures were determined by spectral and chemical methods.
- Hirakura, Kazuhiro,Morita, Makoto,Nakajima, Kaoru,Ikeya, Yukinobu,Mitsuhashi, Hiroshi
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p. 3327 - 3333
(2007/10/02)
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- THE CONVERSION OF PRIMARY ALCOHOLS TO THE CORRESPONDING ALDEHYDES BY A MODIFIED LEAD TETRAACETATE OXIDATION
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A novel metod for obtaining aldehydes in good yield from primary alcohols has been devised, using the combination lead tetraacetate-manganous diacetate as the oxidizing agent.
- Mihailovic, M. Lj.,Konstantinovic, S.,Vukicevic, R.
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p. 2287 - 2290
(2007/10/02)
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- Processes for producing 7-octen-1-al and derivatives thereof
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There are disclosed a process for producing 7-octen-1-al which comprises isomerizing 2,7-octadien-1-ol in the presence of a catalyst comprising oxides of at least two metals selected from the group consisting of copper, chromium and zinc and processes for producing derivatives of 7-octen-1-al.
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- Mechanistic Studies on Non-Heme Iron Monooxygenase Catalysis: Epoxidation, Aldehyde Formation, and Demethylation by the ω-Hydroxylation System of Pseudomonas oleovorans
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In previous work we have established that the "ω-hydroxylation" system of P. oleovorans readily converts terminal olefins to the corresponding 1,2-oxides and does so stereoselectively.We also demonstrated loss of olefin configuration during enzymatic epoxidation, a result inconsistent with a concerted epoxidation mechanism (J.Am.Chem.Soc. 1977, 99, 2017-2024).Since loss of olefin configuration is unprecedented for monooxygenase-catalyzed epoxidations these studies have been confirmed with isolated enzymes and further extended in order to probe the mechanism of non-heme iron monooxygenase catalysis.Enzymatic epoxidation of both cis- and trans-1-deuterio-1-octene proceeds with about 70percent inversion of the olefinic configuration, with corresponding results being obtained for the two olefins.As we reported in a preliminary communication (Bio/Technology 1983, 1, 677-686, the ω-hydroxylation system also produces aldehydes from olefins.Aldehyde formations exhibits the reaction characteristics expected for the usual oxygenase pathway.Deuterium migration from C-1 to C-2 occurs in formation of aldehyde from olefin, although loss of deuterium also occurs.The ω-hydroxylation system was found to efficiently catalyze O-demethylation of heptyl methyl ether, the first demonstration of such activity for a non-heme iron monooxygenase of this type.Taken together, the results provide support for a two-step mechanism involving enzyme generated species with cationic and/or radical character, which accounts for the stereoselectivity, configurational loss, substrate specificity, formation of aldehydes with deuterium migration, and demethylation activity exhibited by this enzyme system.
- Katopodis, Andreas, G.,Wimalasena, Kandatege,Lee, Joseph,May, Sheldon W.
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p. 7928 - 7935
(2007/10/02)
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- HYDROGEN TRANSFER REACTION OF ALLYLIC ALCOHOLS CATALYZED BY A MOLYBDENUM COMPLEX
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Allylic alcohols undergo hydrogen transfer reactions in the presence of a catalytic amount of the dinitrogen complex trans-Mo(N2)2(dppe)2 (dppe = Ph2PCH2CH2PPh2).From the acyclic allylic alcohols, saturated carbonyl compounds were obtained as the main products whereas from the cyclic allylic alcohols, unsaturated ketones and saturated alcohols were formed predominantly.Accompanying the hydrogen transfer reaction, a decarbonylation reaction occurred simultaneously to give a molybdenum carbonyl complex, cis-(Mo(CO)2(dppe)2 as well as the hydrocarbon in certain cases.The mechanisms of both reactions are discussed.
- Lin, Yingrui,Lu, Xiyan
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p. 321 - 326
(2007/10/02)
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