- Olefination of activated halides and mesylates using arsonium ylides
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Alkyltriphenylarsonium ylides react with activated primary halides and mesylates to afford olefins in good yields and with high E-selectivity.
- Seyer, Andre,Alcaraz, Lilian,Mioskowski
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- Z-Selective Cross-Metathesis and Homodimerization of 3E-1,3-Dienes: Reaction Optimization, Computational Analysis, and Synthetic Applications
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Olefin metathesis reactions with 3E-1,3-dienes using Z-selective cyclometalated ruthenium benzylidene catalysts are described. In particular, a procedure for employing 3E-1,3-dienes in Z-selective homodimerization and cross-metathesis with terminal alkenes is detailed. The reaction takes advantage of the pronounced chemoselectivity of a recently reported ruthenium-based catalyst containing a cyclometalated NHC ligand for terminal alkenes in the presence of internal E-alkenes. A wide array of commonly encountered functional groups can be tolerated, and only a small excess (1.5 equiv) of the diene coupling partner is required to achieve high yields of the desired internal E,Z-diene cross-metathesis product. Computational studies have been performed to elucidate the reaction mechanism. The computations are consistent with a diene-first pathway. The reaction can be used to quickly assemble structurally complex targets. The power of this cross-metathesis reaction is demonstrated by the concise syntheses of two insect pheromones.
- Luo, Shao-Xiong,Cannon, Jeffrey S.,Taylor, Buck L. H.,Engle, Keary M.,Houk,Grubbs, Robert H.
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- Biosynthesis of C11 and C16 homoterpenes in higher plants; stereo- chemistry of the C-C-bond cleavage reaction
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In higher plants the C11 homoterpene 4,8-dimethylnona-1,3,7-triene (1) originates from oxidative degradation of nerolidol (3) or geranylacetone (4). The geometry of the transition state of bond cleavage has been shown to be syn-periplanar, for both 3 and 4 by application of chirally labelled, deuterated precursors to flowers of Magnolia liliiflora nigra or leaves of the Lima bean Phaseolus lunatus. The synthesis of the deuterated, chiral metabolic probes 3 and 8 from nor-farnesene (5), via the enantiomeric epoxides (2S,3R)-6 and ent-6, is described.
- Boland, Wilhelm,Gaebler, Andreas,Gilbert, Matthias,Feng, Zhuofu
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- Herbivore-induced and floral homoterpene volatiles are biosynthesized by a single P450 enzyme (CYP82G1) in Arabidopsis
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Terpene volatiles play important roles in plant-organism interactions as attractants of pollinators or as defense compounds against herbivores. Among the most common plant volatiles are homoterpenes, which are often emitted from night-scented flowers and from aerial tissues upon herbivore attack. Homoterpene volatiles released from herbivore-damaged tissue are thought to contribute to indirect plant defense by attracting natural enemies of pests. Moreover, homoterpenes have been demonstrated to induce defensive responses in plant-plant interaction. Although early steps in the biosynthesis of homoterpenes have been elucidated, the identity of the enzyme responsible for the direct formation of these volatiles has remained unknown. Here, we demonstrate that CYP82G1 (At3g25180), a cytochrome P450 monooxygenase of the Arabidopsis CYP82 family, is responsible for the breakdown of the C20-precursor (E,E)-geranyllinalool to the insect-induced C16-homoterpene (E,E)-4,8,12-trimethyltrideca-1,3,7,11-tetraene (TMTT). Recombinant CYP82G1 shows narrow substrate specificity for (E,E)- geranyllinalool and its C 15-analog (E)-nerolidol, which is converted to the respective C 11-homoterpene (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT). Homology-based modeling and substrate docking support an oxidative bond cleavage of the alcohol substrate via syn-elimination of the polar head, together with an allylic C-5 hydrogen atom. CYP82G1 is constitutively expressed in Arabidopsis stems and inflorescences and shows highly coordinated herbivoreinduced expression with geranyllinalool synthase in leaves depending on the F-box protein COI-1. CYP82G1 represents a unique characterized enzyme in the plant CYP82 family with a function as a DMNT/TMTT homoterpene synthase.
- Lee, Sungbeom,Badieyan, Somayesadat,Bevan, David R.,Herde, Marco,Gatz, Christiane,Tholl, Dorothea
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- Amides as bioisosteres of triazole-based geranylgeranyl diphosphate synthase inhibitors
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Geranylgeranyl diphosphate synthase (GGDPS) inhibitors are of potential therapeutic interest as a consequence of their activity against the bone marrow cancer multiple myeloma. A series of bisphosphonates linked to an isoprenoid tail through an amide linkage has been prepared and tested for the ability to inhibit GGDPS in enzyme and cell-based assays. The amides were designed as analogues to triazole-based GGDPS inhibitors. Several of the new compounds show GGDPS inhibitory activity in both enzyme and cell assays, with potency dependent on chain length and olefin stereochemistry.
- Goetz, Daniel B.,Holstein, Sarah A.,Varney, Michelle L.,Wiemer, David F.
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- Highly Selective and Catalytic Generation of Acyclic Quaternary Carbon Stereocenters via Functionalization of 1,3-Dienes with CO2
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The catalytic asymmetric functionalization of readily available 1,3-dienes is highly important, but current examples are mostly limited to the construction of tertiary chiral centers. The asymmetric generation of acyclic products containing all-carbon quaternary stereocenters from substituted 1,3-dienes represents a more challenging, but highly desirable, synthetic process for which there are very few examples. Herein, we report the highly selective copper-catalyzed generation of chiral all-carbon acyclic quaternary stereocenters via functionalization of 1,3-dienes with CO2. A variety of readily available 1,1-disubstituted 1,3-dienes, as well as a 1,3,5-triene, undergo reductive hydroxymethylation with high chemo-, regio-, E/Z-, and enantioselectivities. The reported method features good functional group tolerance, is readily scaled up to at least 5 mmol of starting diene, and generates chiral products that are useful building blocks for further derivatization. Systemic mechanistic investigations using density functional theory calculations were performed and provided the first theoretical investigation for an asymmetric transformation involving CO2. These computational results indicate that the 1,2-hydrocupration of 1,3-diene proceeds with high π-facial selectivity to generate an (S)-allylcopper intermediate, which further induces the chirality of the quaternary carbon center in the final product. The 1,4-addition of an internal allylcopper complex, which differs from previous reports involving terminal allylmetallic intermediates, to CO2 kinetically determines the E/Z- and regioselectivity. The rapid reduction of a copper carboxylate intermediate to the corresponding silyl-ether in the presence of Me(MeO)2SiH provides the exergonic impetus and leads to chemoselective hydroxymethylation rather than carboxylation. These results provide new insights for guiding further development of asymmetric C-C bond formations with CO2
- Chen, Xiao-Wang,Zhu, Lei,Gui, Yong-Yuan,Jing, Ke,Jiang, Yuan-Xu,Bo, Zhi-Yu,Lan, Yu,Li, Jing,Yu, Da-Gang
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p. 18825 - 18835
(2019/11/28)
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- Organoselenium-Catalyzed Regioselective C?H Pyridination of 1,3-Dienes and Alkenes
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An efficient approach for organoselenium-catalyzed regioselective C?H pyridination of 1,3-dienes to form pyridinium salts has been developed. This method was also successfully applied to direct C?H pyridination of alkenes. Fluoropyridinium reagents, or initially loaded pyridine derivatives, acted as pyridine sources in the pyridination reactions. The obtained pyridinium salts could be further converted under different conditions. This work is the first example of catalytic C-2 direct C?H functionalization of 1,3-dienes and the first case of organoselenium-catalyzed C?H pyridination.
- Liao, Lihao,Guo, Ruizhi,Zhao, Xiaodan
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p. 3201 - 3205
(2017/03/17)
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- Catalytic enantioselective 1,2-diboration of 1,3-dienes: Versatile reagents for stereoselective allylation
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More with boron: The development of catalytic enantioselective 1,2-diboration of 1,3-dienes enables a new strategy for enantioselective carbonyl allylation reactions (see scheme). These reactions occur with outstanding levels of stereoselection and can be applied to both monosubstituted and 1,1-disubstituted dienes. The carbonyl allylation reactions provide enantiomerically enriched functionalized homoallylic alcohol products. Copyright
- Kliman, Laura T.,Mlynarski, Scott N.,Ferris, Grace E.,Morken, James P.
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p. 521 - 524
(2012/03/11)
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- A direct synthesis of functionalized styrenes and terminal 1,3-dienes via aqueous Wittig chemistry with formalin
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A direct synthesis of functionalized styrenes including synthetically valuable styryl halides and terminal 1,3-dienes is reported directly from benzylic and allylic alcohols and aqueous formalin involving microwave assisted phosphonium salt formation and Wittig olefination under mildly basic conditions.
- Das, Priyabrata,McLeod, David,McNulty, James
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experimental part
p. 199 - 201
(2011/02/26)
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- Efficient one-to-one coupling of easily available 1,3-dienes with carbon dioxide
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An efficient one-to-one coupling reaction of atmospheric pressure carbon dioxide with 1,3-dienes is realized for the first time through PSiP-pincer type palladium-catalyzed hydrocarboxylation. The reaction is applicable to various 1,3-dienes including easily available chemical feedstock such as 1,3-butadiene and isoprene. This protocol affords a highly useful method for the synthesis of β,γ-unsaturated carboxylic acid derivatives from CO2.
- Takaya, Jun,Sasano, Kota,Iwasawa, Nobuharu
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supporting information; experimental part
p. 1698 - 1701
(2011/05/04)
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- Asymmetric [4 + 3] cycloadditions between vinylcarbenoids and dienes: Application to the total synthesis of the natural product (-)-5-epi-vibsanin E
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The total synthesis of (-)-5-epi-vibsanin E (2) has been achieved in 18 steps. The synthesis combines the rhodium-catalyzed [4 + 3] cycloaddition between a vinylcarbenoid and a diene to rapidly generate the tricycliccore with an effective end game strategy to introduce the remaining sid e-chains. The [4 + 3] cycloaddition occurs by a cyclopropanation to forma divinylcyclopropane followed by a Cope rearrangement to form a cycloh eptadiene. The quaternary stereogenic center generated in the process can be obtained with high asymmetric induction when the reaction is catalyzed by the chiral dirhodium complex, Rh2(S-PTAD)4.
- Schwartz, Brett D.,Denton, Justin R.,Lian, Yajing,Davies, Huw M. L.,Williams, Craig M.
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supporting information; experimental part
p. 8329 - 8332
(2009/12/02)
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- Copper-catalyzed tandem oxidation-olefination process
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A novel catalytic sequence aerobic oxidation-olefination has been developed. A single and inexpensive copper catalyst provides a large range of olefins from alcohols in good to excellent yields. The reaction exhibits excellent functional group compatibili
- Davi, Michael,Lebel, Helene
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supporting information; experimental part
p. 41 - 44
(2009/07/11)
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- Synthesis of moenocinol and its analogs using BT-sulfone in Julia-Kocienski olefination
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Moenocinol (C25H42O), the acyclic terpenoid unsaturated lipid part of moenomycin antibiotics, was prepared by an expedient method, which comprised organometallic reaction, Julia-Kocienski olefination, and enolate carbon bond formation as the key steps. The starting materials, nerol and 3-butyn-1-ol, were elaborated to the benzothiazole sulfone 2 and aldehyde 3, and the subsequent Julia-Kocienski olefination occurred in a stereospecific manner to give the desired 6E-configuration of moenocinol. Moenocinol (1) was thus synthesized by 10 linear steps in 12% overall yield, and its analogs 23, 24, and 28 with different chain lengths and unsaturation degrees were also realized by the similar reaction sequences.
- Huang, Hung-Jyun,Yang, Wen-Bin
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p. 1429 - 1433
(2008/02/02)
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- Copper-carbene complexes as catalysts in the synthesis of functionalized styrenes and aliphatic alkenes
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(NHC)-Cu (NHC = N-heterocyclic carbene) complexes efficiently catalyzed the methylenation of a variety of aliphatic and aromatic aldehydes and ketones in the presence of trimethylsilyldiazomethane, triphenylphosphine, and 2-propanol. The copper catalysts are not only inexpensive compared to rhodium complexes, but they also exhibit better functional group compatibility with aromatic aldehydes and ketones. Indeed very high yields were obtained for the formation of styrenes containing nitro, trifluoromethyl, amino, and ester groups, as well as for pyridine-, pyrrole-, and indole-substituted alkenes.
- Lebel, Helene,Davi, Michael,Diez-Gonzalez, Silvia,Nolan, Steven P.
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p. 144 - 149
(2007/10/03)
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- Rhodium-catalyzed synthesis of terminal alkenes
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Terminal alkenes have been efficiently prepared via a rhodium-catalyzed olefination procedure using Wilkinson's catalyst in the presence of triphenylphosphine, 2-propanol and trimethylsilyldiazomethane. Optimized reaction conditions are described for aldehydes and ketones, as well as alternative work up procedures. Georg Thieme Verlag Stuttgart.
- Paquet, Valerie,Lebel, Helene
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p. 1901 - 1905
(2007/10/03)
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- Rhodium-Catalyzed Methylenation of Aldehydes
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The rhodium-catalyzed methylenation of aldehydes using trimethylsilyldiazomethane and triphenylphosphine produces a variety of terminal alkenes in excellent yields. These mild and nonbasic reaction conditions allow the conversion of enolizable substrates (keto aldehydes and nonracemic α-substituted aldehydes) to terminal alkenes without epimerization. Optimization of the reaction conditions led to the conclusion that a variety of rhodium(I) sources can be used as catalysts. The effect of the solvent on the reaction has also been studied, and it indicates that although the THF is the best solvent, other solvents may be used. The reactivity of the system is very much dependent on the nature of the phosphine reagent. The use of an easily removable phosphine is also described. Spectroscopic studies indicate that the reaction proceeds via an unusual mechanism which leads to the in situ formation of the salt-free phosphorus ylide, methylenetriphenylphosphorane.
- Lebel, Helene,Paquet, Valerie
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p. 320 - 328
(2007/10/03)
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- Semiochemical
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cis-Jasmone has been discovered to be useful as a semiochemical that changes the behaviour of insects and/or the physiology of plants. It has direct signalling roles with plant-feeding aphids, in attraction of aphid predators and parasitoids, and may act as an airborne signal inducing production of volatile plant semiochemicals, including the monoterpene (E)-β-ocimene, that stimulate foraging by parasitoids. It is an extremely benign compound having, to human beings, a pleasant aroma and gives a long-lasting effect after removal of the stimulus.
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- A highly stereoselective synthesis of (E)-α-bromoacrylates
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Novel reagent, methyl bis(2,2,2-trifluoroethoxy)bromophosphonoacetate (5a), was designed and prepared in order to efficiently synthesize (E)-α-bromoacrylates 7, from which widely useful precursors for various C-C bond formations were prepared. Horner-Wadsworth-Emmons (HWE) reaction of various aldehydes with 5a in the presence of t-BuOK and 18-C-6 gave corresponding (E)-α-bromoacrylate derivatives with high stereoselectivity and excellent yield. Using the product (E)-α-bromoacrylate 7s as a key intermediate, we succeeded in developing the most effective route of plaunotol synthesis via Suzuki cross-coupling. (C) 2000 Elsevier Science Ltd.
- Tago, Keiko,Kogen, Hiroshi
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p. 8825 - 8831
(2007/10/03)
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- Sulfur ylide vinylation of halides and mesylates
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One-carbon homologation of benzylic, allylic, propargylic and primary halides or mesylates with dimethylsulfonium methylide affords terminal olefins in good to excellent yields.
- Alcaraz,Harnett,Mioskowski,Martel,Le Gall,Shin, Dong-Soo,Falck
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p. 5453 - 5456
(2007/10/02)
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- (E)-4,8-DIMETHYL-1,3,7-NONATRIENE AND (E,E)-4,8,12-TRIMETHYL-1,3,7,11-TRIDECATETRAENE, TWO UNUSUAL HYDROCARBONS FROM CARDAMOM OIL
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The identification of two new natural products, (E)-4,8-dimethyl-1,3,7-nonatriene 1 and (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene 3 is reported.These unusual C11 and C16 hydrocarbons were isolated from essential oil of Elettaria cardamomum Maton var. miniscula Burkhill (Zingiberaceae) and their structures confirmed by synthesis.
- Maurer, Bruno,Hauser, Arnold,Froidevaux, Jean-Claude
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p. 2111 - 2112
(2007/10/02)
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- RECENT SULPHONE-BASED OLEFINATION REACTIONS
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The scope, limitations, and recent applications of two olefination reactions based on the reductive elimination of β-acyloxy sulphones (the Julia olefination) and the fluoride-induced elimination of β-trimethylsilyl sulphones is reviewed.
- Kocienski, Philip
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- Decomposition et proprietes electrophiles des carbenoides monohalogenes non fonctionnels
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Geminal substitution of a carbon atom by a halogen atom and a lithium atom gives rise to electrophilic properties and great instability to the corresponding α-monohalogenoalkyllithium.From NMR data, it appears that the functional carbon atom exhibits an electron deficiency in connection with an intramolecular halogen-lithium coordination.This description is in agreement with the structure proposed for LiCH2F on the basis of "ab initio" calculations.Electronic and steric effects of the other substituents of the functional carbon atom and the influence of the reaction medium (basicity of solvents, Lewis acidity of associated salts) on the variation of electrophilic and nucleophilic behaviour and stability of carbenoids (mono, di, trihalogeno) can be rationalized on the basis of this metallocarbenium halogenide structure.
- Villieras, J.,Rambaud, M.,Kirschleger, B.,Tarhouni, R.
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p. 837 - 843
(2007/10/02)
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- A New Synthesis of Olefins via the Elimination Reaction of β-Tributylstannyl Organosulfur Compounds
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Organosulfur compounds on treatment with butyllithium in tetrahydrofuran followed by tributylstannylmethyl iodide 1 afforded olefins.The reaction was found to proceed via the destannylsulfurization of the initially formed β-stannyl organosulfur compounds.Thus, allyl 2-pyridyl sulfides 2 or allyl phenyl sulfones 12 were converted into 1,3-dienes 4.Compounds 13 and 15 were converted into the olefins 14 and 17.Furthermore, the reaction was applied to the synthesis of α-substituted vinyl sulfides 24 and allene 27.The stereochemistry of the double bond is discussed.Keywords - destannylsulfurization; allyl 2-pyridyl sulfide; allyl phenyl sulfone; synthesis of olefin; 1,3-diene; vinyl sulfide; β-tributylstannyl organosulfur compound.
- Ochiai, Masahito,Ukita, Tatsuzo,Fujita, Eiichi,Tada, Shin-ichi
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p. 1829 - 1839
(2007/10/02)
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- A NEW SYNTHESIS OF 1,3-DIENES FROM ALLYL SULFIDES AND ALLYL SULFONES USING TRI-n-BUTYLSTANNYLMETHYL IODIDE
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Allyl 2-pyridyl sulfide 6 or allyl phenyl sulfone 7 on treatment with n-butyllithium in tetrahydrofuran followed by tri-n-butylstannylmethyl iodide (4) afforded directly the 1,3-diene 8 in good yield.
- Ochiai, Masahito,Tada, Shin-ichi,Sumi, Kenzo,Fujita, Eiichi
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p. 2205 - 2208
(2007/10/02)
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