- Palladium-catalyzed oxidative borylation of conjugated enynones through carbene migratory insertion: synthesis of furyl-substituted alkenylboronates
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A palladium-catalyzed oxidative borylation reaction of conjugated enynones is developed. This reaction represents a new method for the synthesis of furyl-substituted alkenylboronates. The reaction works well with a series of conjugated enynones. Boryl migratory insertion of the palladium carbene intermediate is proposed as the key step in these transformations.
- Ping, Yifan,Chang, Taiwei,Wang, Kang,Huo, Jingfeng,Wang, Jianbo
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supporting information
p. 59 - 62
(2019/01/03)
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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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p. 1630 - 1639
(2019/01/26)
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- Chemoselective Biohydrogenation of Alkenes in the Presence of Alkynes for the Homologation of 2-Alkynals/3-Alkyn-2-ones into 4-Alkynals/Alkynols
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The chemoselective hydrogenation of alkenes in the presence of alkynes is a very challenging transformation to achieve with traditional chemical methods. The development of an effective procedure to perform this transformation would enrich the tool-kit available to organic chemists for the development of useful synthetic routes, and the creation of novel structural motifs. The reduction of activated alkene bonds by ene-reductases (ERs) is completely chemoselective, because of the mechanism of the reaction. Thus, we investigated the use of ERs belonging to the Old Yellow Enzyme family for the reduction of α,β-unsaturated aldehydes with a conjugated C≡C triple bond at the γ position. This reaction was exploited as the key step for the development of an effective homologation route to convert aryl and alkyl substituted propynals and butynones into 4-alkynals and 4-alkynols, avoiding some troublesome or hazardous steps of known synthetic routes. (Figure presented.).
- Colombo, Danilo,Brenna, Elisabetta,Gatti, Francesco G.,Ghezzi, Maria Chiara,Monti, Daniela,Parmeggiani, Fabio,Tentori, Francesca
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supporting information
p. 2638 - 2648
(2019/05/16)
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- Synthetic method for organic synthesis intermediate 2-octynaldehyde
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The invention discloses a synthetic method for the organic synthesis intermediate 2-octynaldehyde. The synthetic method comprises the following steps: adding 2-octyne-1-propyl ether and an anhydrous 2-bromopropane solution into a reaction vessel, controlling a solution temperature and a stirring speed, and carrying out a reaction; and then adding cadmium selenide powder and an anhydrous ethylene glycol carbonate solution in batches, raising the temperature, continuing the reaction, lowering the temperature, carrying out standing, subjecting the solution to layering, separating an oil layer, washing the oil layer in an anhydrous 2,5-dimethylfuran solution a plurality of times, then washing the oil layer in an anhydrous dimethyl sulphoxide solution a plurality of times, carrying out recrystallization in an anhydrous diethylene glycol solution, and then carrying out dehydration with a dehydrating agent to obtain the finished 2-octynaldehyde.
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Paragraph 0012; 0013; 0016; 0017; 0018 - 0021
(2018/07/30)
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- [4+2] or [4+1] Annulation: Changing the Reaction Pathway of a Rhodium-Catalyzed Process by Tuning the Cp Ligand
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A change in reaction pathway was achieved for the first time by tuning the cyclopentadienyl (Cp) ligand used for the rhodium-catalyzed cyclization of benzamides with conjugated enynones. Depending on the Cp ligand, the reaction pathway switched between [4+2] and [4+1] annulation. Electronic effects turned out to be crucial for the product distribution. The dichotomy was attributed to the alteration of the Lewis acidity of the resultant Cp-bound rhodium species.
- Hong, Seung Youn,Jeong, Jisu,Chang, Sukbok
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supporting information
p. 2408 - 2412
(2017/02/23)
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- Catalytic Enantioselective Synthesis of Amino Skipped Diynes
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The Cu-catalyzed synthesis of nonracemic 3-amino skipped diynes via an enantiodetermining C-C bond formation is described using StackPhos as ligand. Despite challenging issues of reactivity and stereoselectivity inherent to these chiral skipped diynes, the reaction tolerates an extremely broad substrate scope with respect to all components and provides the title compounds in excellent enantiomeric excess. The alkyne moieties are demonstrated here to be useful synthetic handles, and 3-amino skipped diynes are convenient building blocks for enantioselective synthesis.
- Paioti, Paulo H. S.,Abboud, Khalil A.,Aponick, Aaron
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supporting information
p. 2150 - 2153
(2016/03/05)
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- Palladium-Catalyzed Oxidative Cross-Coupling of Conjugated Enynones with Organoboronic Acids
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A palladium-catalyzed oxidative cross-coupling reaction of conjugated enynones with organoboronic acids is developed. This reaction provides an efficient methodology for the synthesis of functionalized furan derivatives, including 2-alkenylfurans and furan-substituted 1,3-dienes. Palladium-carbene migratory insertion is proposed as the key step in these transformations. Notably, the β-hydride elimination process occurs in a stereoselective manner, resulting in the formation of double bonds with high (E)-selectivity.
- Xia, Ying,Ge, Rui,Chen, Li,Liu, Zhen,Xiao, Qing,Zhang, Yan,Wang, Jianbo
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p. 7856 - 7864
(2015/09/01)
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- Pd-catalyzed cross-coupling of terminal alkynes with ene-yne-ketones: Access to conjugated enynes via metal carbene migratory insertion
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A novel strategy for alkyne-alkyne cross-coupling has been developed under the palladium catalysis. In this reaction, ene-yne-ketones are employed as carbene precursors, which couple with terminal alkynes through the metal carbene migratory insertion process. Furan-substituted enynes are obtained in good yields and in a stereoselective manner.
- Xia, Ying,Liu, Zhen,Ge, Rui,Xiao, Qing,Zhang, Yan,Wang, Jianbo
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supporting information
p. 11233 - 11235
(2015/07/07)
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- Copper(II)-catalyzed silylation of activated alkynes in water: Diastereodivergent access to E- or Z-β-silyl-α,β-unsaturated carbonyl and carboxyl compounds
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Copper(II)-catalyzed silylation of substituted alkynylcarbonyl compounds was investigated. Through the activation of Me2PhSiBpin in water at room temperature and open atmosphere, vinylsilanes conjugated to carbonyl groups are synthesized in high yield. A surprising diastereodivergent access to olefin geometry was discovered using a silyl conjugate addition strategy: aldehydes and ketones were Z selective while esters and amides were exclusively transformed into the E products. Dial a diastereomer: The title reaction proceeds through the activation of Me2PhSiBpin in water at room temperature and open atmosphere to produce high yields of vinylsilanes conjugated to carbonyl groups. A surprising diastereodivergent access to olefin geometry was discovered using this silyl conjugate addition strategy: aldehydes were Z selective while esters and amides exclusively delivered the E-configured products.
- Calderone, Joseph A.,Santos, Webster L.
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supporting information
p. 4154 - 4158
(2014/05/06)
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- Copper-Catalyzed Propargylic Substitution of Dichloro Substrates: Enantioselective Synthesis of Trisubstituted Allenes and Formation of Propargylic Quaternary Stereogenic Centers
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An easy and versatile Cu-catalyzed propargylic substitution process is presented. Using easily prepared prochiral dichloro substrates, readily available Grignard reagents together with catalytic amount of copper salt and chiral ligand, we accessed a range of synthetically interesting trisubstituted chloroallenes. Substrate scope and nucleophile scope are broad, providing generally high enantioselectivity for the desired 1,3-substitution products. The enantioenriched chloroallenes could be further transformed into the corresponding trisubstituted allenes or terminal alkynes bearing all-carbon quaternary stereogenic centers, through the copper-catalyzed enantiospecific 1,1/1,3-substitutions. The two successive copper-catalyzed reactions could be eventually combined into a one-pot procedure and different desired allenes or alkynes were obtained respectively with high enantiomeric excesses.
- Li, Hailing,Grassi, David,Guénée, Laure,Bürgi, Thomas,Alexakis, Alexandre
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supporting information
p. 16694 - 16706
(2016/02/12)
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- An expedient osmium(vi)/K3Fe(CN)6-mediated selective oxidation of benzylic, allylic and propargylic alcohols
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A chemoselective osmium(vi) catalyzed oxidation of benzylic, allylic and propargylic alcohols using K3Fe(CN)6as a secondary oxidant is described. This protocol is operationally simple and exhibits excellent chemoselectivity favouring the oxidation of benzylic alcohols over the aliphatic alcohols. A larger scale reaction was also found to be compatible. This journal is
- Fernandes, Rodney A.,Bethi, Venkati
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p. 40561 - 40568
(2015/02/18)
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- Palladium-catalyzed carbene migratory insertion using conjugated ene-yne-ketones as carbene precursors
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Palladium-catalyzed cross-coupling reactions between benzyl, aryl, or allyl bromides and conjugated ene-yne-ketones lead to the formation of 2-alkenyl-substituted furans. This novel coupling reaction involves oxidative addition, alkyne activation-cyclization, palladium carbene migratory insertion, β-hydride elimination, and catalyst regeneration. Palladium (2-furyl)carbene is proposed as the key intermediate, which is supported by DFT calculations. The palladium carbene character of the key intermediate is validated by three aspects, including bond lengths, Wiberg bond order indices, and molecular orbitals, by comparison to those reported for stable palladium carbene species. Computational studies also revealed that the rate-limiting step is ene-yne-ketone cyclization, which leads to the formation of the palladium (2-furyl)carbene, while the subsequent carbene migratory insertion is a facile process with a low energy barrier (5 kcal/mol).
- Xia, Ying,Qu, Shuanglin,Xiao, Qing,Wang, Zhi-Xiang,Qu, Peiyuan,Chen, Li,Liu, Zhen,Tian, Leiming,Huang, Zhongxing,Zhang, Yan,Wang, Jianbo
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supporting information
p. 13502 - 13511
(2013/09/24)
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- N-heterocyclic carbene-catalyzed annulation of α-cyano-1,4-diketones with ynals
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In this paper, the first stereoselective annulation reaction between r-cyano-1,4-diketones and ynals, mediated by catalytic amounts of a triazolium salt precatalyst and cocatalytic amounts of a weak carboxylate base, is disclosed. The title transformation proceeds smoothly under mild reaction conditions and generates three contiguous stereogenic centers, one of which is a quaternary acetal carbon. This reaction tolerates a wide variety of electronically distinct substituents on both reaction partners and affords privileged bicyclic scaffolds in 61-90% isolated yields and with up to 20:1 diastereomeric preference.
- Romanov-Michailidis, Fedor,Besnard, Celine,Alexakis, Alexandre
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supporting information
p. 4906 - 4909,4
(2012/12/12)
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- N-heterocyclic carbene-catalyzed annulation of α-cyano-1,4-diketones with ynals
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In this paper, the first stereoselective annulation reaction between r-cyano-1,4-diketones and ynals, mediated by catalytic amounts of a triazolium salt precatalyst and cocatalytic amounts of a weak carboxylate base, is disclosed. The title transformation proceeds smoothly under mild reaction conditions and generates three contiguous stereogenic centers, one of which is a quaternary acetal carbon. This reaction tolerates a wide variety of electronically distinct substituents on both reaction partners and affords privileged bicyclic scaffolds in 61-90% isolated yields and with up to 20:1 diastereomeric preference.
- Romanov-Michailidis, Fedor,Besnard, Céline,Alexakis, Alexandre
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supporting information
p. 4906 - 4909
(2013/01/15)
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- One-pot synthesis of trichloromethyl carbinols from primary alcohols
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Versatile trichloromethyl carbinols can be prepared in one pot from primary alcohols by treatment with Dess-Martin periodinane (DMP) in CHCl3 followed by introduction of commercially available 1,5,7-triazabicyclo[4.4.0] dec-5-ene (TBD). A modification of the method was used to convert chiral primary alcohol (R)-(-)-2,2-dimethyl-1,3-dioxolane-4-methanol to the corresponding trichloromethyl carbinol with complete stereochemical fidelity, despite the reactant proceeding through a base-sensitive aldehyde intermediate.
- Gupta, Manoj K.,Li, Zhexi,Snowden, Timothy S.
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experimental part
p. 4854 - 4860
(2012/07/30)
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- Synthesis of polyfunctional allenes by successive copper-mediated substitutions
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Readily available 1,1-dichloro-2-alkynes are versatile starting materials for the synthesis of polyfunctionalized allenes. They can be prepared from commercially available terminal alkynes in a two-step procedure. The Cu-mediated reaction of several 1,1-propargylic derivatives with functionalized alkyl, benzylic, or allylic zinc reagents proceeds exclusively with S N2′ selectivity and allows a rapid and efficient synthesis of functionalized chloroallenes. These chloroallenes undergo a novel Cu I-catalyzed substitution reaction with functionalized arylmagnesium reagents with excellent SN2 selectivity to give trisubstituted polyfunctionalized allenes. The functional group tolerance is excellent and functionalities, such as cyano, keto, ester, phosphate, trifluoromethyl, and halogens, are well tolerated. Copyright
- Schade, Matthias A.,Yamada, Shigeyuki,Knochel, Paul
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scheme or table
p. 4232 - 4237
(2011/05/15)
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- Synthesis of pyrazoles via electrophilic cyclization
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Electrophilic cyclizations of α,β-alkynic hydrazones by molecular iodine were investigated for the synthesis of 4-iodopyrazoles. α,β-Alkynic hydrazones were readily prepared by the reactions of hydrazines with propargyl aldehydes and ketones. When treated with molecular iodine in the presence of sodium bicarbonate, α,β-alkynic hydrazones underwent electrophilic cyclization to afford 4-iodopyrazoles in good to high yields. Iodocyclization was general for a wide range of α,β-alkynic hydrazones and tolerated the presence of aliphatic, aromatic, heteroaromatic, and ferrocenyl moieties with electron-withdrawing and electron-donating substituents.
- Zora, Metin,Kivrak, Arif,Yazici, Ceyda
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scheme or table
p. 6726 - 6742
(2011/10/09)
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- Synthesis of pyrazoles via CuI-mediated electrophilic cyclizations of α,β-alkynic hydrazones
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Synthesis of pyrazoles via electrophilic cyclization of α,β-alkynic hydrazones by copper(I) iodide is described. When treated with copper(I) iodide in the presence of triethylamine in refluxing acetonitrile, α,β-alkynic hydrazones, prepared readily from hydrazines and propargyl aldehydes and ketones, undergo electrophilic cyclization to afford pyrazole derivatives in good to excellent yields. The reaction appears to be general for a variety of α,β-alkynic hydrazones and tolerates the presence of aliphatic, aromatic, and ferrocenyl moieties with electron-withdrawing and electron-donating substituents.
- Zora, Metin,Kivrak, Arif
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scheme or table
p. 9379 - 9390
(2012/01/06)
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- Biooxidation of Primary Alcohols to Aldehydes through Hydrogen Transfer Employing Janibacter terrae
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Chemoselective oxidations still represent a challenge for chemists. Lyophilized cells of Janibacter terrae were employed for the chemoselective oxidation of primary alcohols to the corresponding aldehydes by hydrogen transfer with the use of acetaldehyde as the hydrogen acceptor. Secondary alcohol moieties were transformed at a much slower rate. The substrate spectrum encompasses substituted benzyl alcohols, whereby substrates with a substituent in the meta position were well tolerated, whereas only very small substituants were tolerated in the ortho position. Furthermore, nalkanols and allylic alcohols were transformed with good conversions. The biocatalyst was compatible with DMSO as a water miscible organic solvent up to 30 % v/v.
- Orbegozo, Thomas,De Vries, Johannes G.,Kroutil, Wolfgang
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experimental part
p. 3445 - 3448
(2010/09/05)
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- Mild and selective hydrozirconation of amides to aldehydes using Cp 2Zr(H)Cl: Scope and mechanistic insight
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An investigation of the use of Cp2Zr(H)Cl (Schwartz's reagent) to reduce a variety of amides to the corresponding aldehydes under very mild reaction conditions and in high yields is reported. A range of tertiary amides, including Weinreb's amides, can be converted directly to the corresponding aldehydes with remarkable chemoselectivity. Primary and secondary amides proved to be viable substrates for reduction as well, although the yields were somewhat diminished as compared to the corresponding tertiary amides. Results from NMR experiments suggested the presence of a stable, 18-electron zirconacycle intermediate that presumably affords the aldehyde upon water or silica gel workup. A series of competition experiments revealed a preference of the reagent for substrates in which the lone pair of the nitrogen is electron releasing and thus more delocalized across the amide bond by resonance. This trend accounts for the observed excellent selectivity for tertiary amides versus esters. Experiments regarding the solvent dependence of the reaction suggested a kinetic profile similar to that postulated for the hydrozirconation of alkenes and alkynes. Addition of p-anisidine to the reaction intermediate resulted in the formation of the corresponding imine mimicking the addition of water that forms the aldehyde.
- Spletstoser, Jared T.,White, Jonathan M.,Tunoori, Ashok Rao,Georg, Gunda I.
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p. 3408 - 3419
(2007/10/03)
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- Total syntheses of (R)-argentilactone and (R)-goniothalamin via catalytic enantioselective allylation of aldehydes
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The total syntheses of (R)-argentilactone (five steps, 25% overall yield) and (R)-goniothalamin (three steps, 61% overall yield) have been described through the enantioselective catalytic allylation of aldehydes (including a propargylic aldehyde) which provided a rapid access to these natural products that display very interesting biological activities.
- De Fátima, ?ngelo,Pilli, Ronaldo Aloise
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p. 8721 - 8724
(2007/10/03)
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- Benzannulation of substituted 3-alkoxycarbonylhex-3-en-5-ynoic acids: A new route to 4-substituted 3,5-dihydroxybenzoic acids derivatives
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A new regioselective pathway to 4-substituted 3,5-dihydroxybenzoic acids derivatives is described here. According to this procedure substituted propargylic aldehydes are converted into substituted 3-alkoxycarbonylhex-3-en-5-ynoic acids, which are in turn, treated with acetic anhydride in the presence of sodium acetate to give the substituted benzoic acids derivatives. The aromatic moiety constructed using the latter benzannulation reaction is formed in regioselective fashion and a range of substituents are tolerated.
- Serra, Stefano,Fuganti, Claudio
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p. 1661 - 1664
(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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- Preparation and applications of fluorinated propargyl phosphonate reagents
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The invention provides new fluorinated γ-tri-substsituted silylpropargyl phosphonates and methods for their use to generate a variety of diverse fluorine-containing compounds. The new fluorinated phosphonate synthons contain a novel juxtaposition of four different functional groups: fluoro, alkynyl, tri-substituted silyl, and phosphonato groups. The latter three of these groups provide convenient handles for the construction of fluorine-containing organic molecules.
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- Unexpected Course of the Reaction of 1,3-Bis(dimethylamino)trimethinium Perchlorate with 3-Substituted Prop-2-ynals Leading to 1-Aryl-2,4,6-triformylbenzenes
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Reaction of 1,3-bis(dimethylamino)trimethinium perchlorate (1) with 3-substituted prop-2-ynals (4) in acetic anhydride at the presence of ZnBr2 gives upon hydrolysis 1-substituted 2,4,6-triformylbenzenes (6) in low to moderate yield. This reaction is restricted to prop-2-ynals bearing electron rich aromatic substituents at the 3-position.
- Suchy, Petr,Dvorak, Dalimil,Havelkova, Martina
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p. 119 - 129
(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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- 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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- SYNTHESIS BY MICROBIAL REDUCTION OF (S)-13-HYDROXY-9Z,11E-OCTADECADIENOIC ACID, A DEFENSIVE SUBSTANCE IN RICE
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(S)-13-Hydroxy-9Z,11E-octadecadienoic acid, a defensive substance in rice, was synthesized with high enantioselectivity by the reduction of the corresponding ketone with yeasts.
- Suemune, Hiroshi,Hayashi, Noriyuki,Funakoshi, Kazuhisa,Akita, Hiroyuki,Oishi, Takeshi,Sakai, Kiyoshi
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p. 2168 - 2170
(2007/10/02)
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