- Merging shuttle reactions and paired electrolysis for reversible vicinal dihalogenations
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Vicinal dibromides and dichlorides are important commodity chemicals and indispensable synthetic intermediates in modern chemistry that are traditionally synthesized using hazardous elemental chlorine and bromine. Meanwhile, the environmental persistence of halogenated pollutants necessitates improved approaches to accelerate their remediation. Here, we introduce an electrochemically assisted shuttle (e-shuttle) paradigm for the facile and scalable interconversion of alkenes and vicinal dihalides, a class of reactions that can be used both to synthesize useful dihalogenated molecules from simple alkenes and to recycle waste material through retro-dihalogenation. The reaction is demonstrated using 1,2-dibromoethane, as well as 1,1,1,2-tetrachloroethane or 1,2-dichloroethane, to dibrominate or dichlorinate, respectively, a wide range of alkenes in a simple setup with inexpensive graphite electrodes. Conversely, the hexachlorinated persistent pollutant lindane could be fully dechlorinated to benzene in soil samples using simple alkene acceptors.
- Dong, Xichang,Roeckl, Johannes L.,Waldvogel, Siegfried R.,Morandi, Bill
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- Preparation of a novel bromine complex and its application in organic synthesis
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Although molecular bromine (Br2) is a useful brominating reagent, it is not easy to handle. Herein, we describe the preparation of a novel air-stable bromine complex prepared from 1,3-dimethyl-2-imidazolidinone (DMI) and Br2, which was identified to be (DMI)2HBr3 by spectral and X-ray techniques. This complex was then used to brominate olefins, carbonyl compounds, and aromatics, as well as in the Hofmann rearrangement. Yields of reaction products using this complex were almost the same or superior to those using other bromine alternatives.
- Nishio, Yuya,Yubata, Kotaro,Wakai, Yutaro,Notsu, Kotaro,Yamamoto, Katsumi,Fujiwara, Hideki,Matsubara, Hiroshi
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p. 1398 - 1405
(2019/02/07)
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- Synthesis of (3Z,13Z)-3,13-octadecadienyl acetate - Sex pheromone of Synanthedon tenuis-using readily available C11-synthon
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Synthesis of (3Z,13Z)-3,13-octadecadienyl acetate has been achieved from the readily available 10-undecen-1-ol using cheaper reagents and less number of steps. In the key step alkylation of an alkyne is performed with solid sodamide giving the product in 50% yield. The method can be easily scaled-up.
- Narasimhan,Ganeshwar Prasad,Madhavan
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- A simple, cost effective synthesis of E,Z-2,13-octadecadienyl acetate, a major sex pheromone component of lepidopteran pests
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A simple, cost effective synthesis of E,Z-2,13-octadecadienyl acetate (1), a major sex pheromone component of many lepidopteran pests, has been achieved in optimum number of steps using cheaper raw meterials.The strategy provides the target compound in 43percent overall yield, and can be scaled up easily.
- Narasimhan, S.,Mohan, H.,Madhavan, S.
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p. 531 - 534
(2007/10/02)
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- Convenient methods for the reduction of amides, nitriles, carboxylic esters, acids and hydroboration of alkenes using NaBH4/I2system
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Reaction of amides with NaBH4-I2 system in THF gives the corresponding amines in 70-76% yields. Reduction of nitriles yields the corresponding amines in 70-75% yields. The I2/NaBH4 system is useful in the hydrocarboration of olefins and the corresponding alcohols are obtained in 78-92% yields after H2O2/OH- oxidation. The reagent system is also useful for the reduction of carboxylic esters and acids to the corresponding alcohols in 60-90% yields.
- Bhanu Prasad,Bhaskar Kanth,Periasamy, Mariappan
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p. 4623 - 4628
(2007/10/02)
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- TETRABUTYLAMMONIUM DIHYDROGENTRIFLUORIDE: AN EFFECTIVE SOURCE OF FLUORIDE ION FOR HALOFLUORINATION OF ALKENES
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Vicinal halofluorides have been prepared from the corresponding alkenes by reaction with a stoichiometric amount of Bu4N+H2F3- as a source of fluoride anion and an excess of an N-halosuccinimide (NXS).The reaction products are obtained in good yields, with a prevalent Markownikoff regiochemistry.Olefins containing hydroxy, epoxy, acetoxy and alkoxy groups do not undergo side reactions under these reaction conditions.
- Albanese, Domenico,Landini, Dario,Penso, Michele,Pratelli, Marco
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p. 537 - 541
(2007/10/02)
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- Efficient Utilization of Tetrabutylammonium Bifluoride in Halofluorination Reactions
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The halofluorination reaction of a variety of alkenes by using tetrabutylammonium bifluoride (TBABF) in the presence of N-halosuccinimide is described.This process occurs stereospecifically to afford anti addition products, and with unsymmetrical olefins a marked Markovnikov-type regioselectivity is observed.In some cases, formation of a remarkable amount of the corresponding dihalo derivatives was found, but this undesirable side reaction can be avoided by using N-iodosucciniumide (NIS) as halogenating agent.If N-bromosuccinimide (NBS) or N-chlorosuccinimide (NCS) is utilized, these dihalo compounds can be easily removed from the halofluorinated compounds by simple column chromatography on silica gel.A mechanism for this side reaction is postulated.
- Camps, F.,Chamorro, E.,Gasol, V.,Guerrero, A.
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p. 4294 - 4298
(2007/10/02)
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- Improved syntheses of hydroxy acid precursors of macrolide pheromones of cucujid grain beetles
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Syntheses of 11- and 12-hydroxy-(Z)-3-dodecenic, 11- and 12-hydroxy-(Z,Z)-3,6-dodecadienic, and 13-hydroxy-(Z,Z)-5,8-tetradecadienic acids are reported.These unsaturated hydroxy acids are precursors of male-produced macrolide aggregation pheromones of grain beetles of the genera Cryptolestes and Oryzaephilus.The sequence of reactions for synthesis of the hydroxy-(Z)-3 acids was carboxylation of the dilithium salt of 10- or 11-hydroxy undecyne, deconjugation of the resulting carboxylic acids with NaNH2 in THF/liquid ammonia to a mixture of 2,3-allenic and 3-alkynoic acids, and hydrogenation of the mixture with P-2 nickel catalyst.This latter reaction gave only the desired hydroxy-(Z)-3-alkenoic acids.The convergent point in the syntheses of the diunsaturated hydroxy-(Z,Z) acids was the coupling of the dimagnesium salt of 3-butyn-1-ol or 5-hexyn-1-ol to the appropriate functionalized propargylic bromide.The resulting 1,4-diacetylenic alcohols were oxidized with Jones reagent to the corresponding carboxylic acids, which were hydrogenated over P-2 nickel catalyst and deprotected.
- Oehlschlager, A. C.,Czyzewska, E.,Aksela, R.,Pierce, H. D.
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p. 1407 - 1413
(2007/10/02)
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- NEW STEREOSPECIFIC SYNTHESES OF PHEROMONE BOMBYKOL AND ITS THREE GEOMETRICAL ISOMERS
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New stereospecific syntheses of the pheromone bombykol and its three geometrical isomers are achieved by palladium-catalyzed cross-coupling reaction between an appropriate alkenylborane and an alkenyl halide in the presence of a base.
- Miyaura, Norio,Suginome, Hiroshi,Suzuki, Akira
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p. 3271 - 3278
(2007/10/02)
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- NEW STEREOSPECIFIC SYNTHESES OF PHEROMONE BOMBYKOL AND ITS THREE GEOMETRICAL ISOMERS
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We describe stereospecific syntheses of pheromone, bombykol and the three geometrical isomers by means of the palladium-catalyzed cross-coupling between an appropriate alkenylborane and an alkenyl halide in the presence of a base.
- Miyaura, Norio,Suginome, Hiroshi,Suzuki, Akira
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p. 1527 - 1530
(2007/10/02)
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- Synthesis of (Z,Z)-11,13-Hexadecadienal, a Principal Component of Navel Orangeworm (Pamyelois transitella) Pheromone
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This report outlines a commercial synthetic process for (Z,Z)-11,13-hexadecadienal (navel orangeworm pheromone).The synthetic scheme which is employed introduces the stereochemically labile conjugated diene moiety at a late stage in the synthesis, thereby avoiding complications during the purification of intermediates.In addition, the aldehyde function is generated through a Grignard reaction sequence, obviating the generally accepted techniques which are usually unsuitable for commercial preparations.We have also observed the first reported selective inclusion by urea of a conjugated (Z,Z)-diene as a means of mild purification of labile dienic pheromone intermediates.
- Bishop, Clyde E.,Morrow, Gary W.
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p. 657 - 660
(2007/10/02)
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- Some Soluble Polydiacetylenes Derived from 10,12-Docosadiyn-1,22-diol
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Synthesis and physical properties of some new soluble polydiacetylenes ontained by solid state polymerization of derivatives of 10,12-Docosadiyn-1,22-diol (1) are described.
- Plachetta, Christoph,Rau, Norbert Otto,Schulz, Rolf C.
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p. 141 - 152
(2007/10/02)
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- Recherches sur la synthese totale des alcaloides appatrenant a la serie de la carpaine et de la cassine. VII. Synthese totale de la (+/-) cassine
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11-Bromoundecan-2-one 6 was prepared in four steps from the commercially available undec-10-en-1-ol 3, and was used to alkylate ethyl 7-methyl-3-oxooct-6-enoate 9.The resulting intermediate was hydrolysed and decarboxylated to give the diketoolefin 11.Ozonolysis of the latter yielded the diketoaldehyde 16, wich was subjected next to condensation with nitroethane in alkaline conditions, followed by catalytic hydrogenation and cyclisation to give a ca. 50/50 mixture of 3-r-hydroxy-6-c (11-oxododecyl)-2-c-methylpiperidine and (+/-)3-epi-cassine. Another route to the key intemediate 11 was also studied, in wich 1,8-dibromooctane 13 was used to alkylate the enolates of ethyl acetoacetate and ethyl 7-methyl-3-oxooct-6-enoate, giving presumably of the olefinic diketodiester 15.Hydrolysis and decarboxylation of the crude reaction product, using aqueous baryum hydroxide, gave the desired compound 11 in an overall yield of 17 percent with respect to 1,8-dibromooctane 13.
- Brown, Eric,Bonte, Alain
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p. 281 - 287
(2007/10/02)
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