- Asymmetric synthesis of avenaciolide via cascade palladium catalysed cyclisation-carbonylation of bromodienes
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An asymmetric synthesis of the secondary metabolite avenaciolide has been achieved utilising a diastereoselective palladium catalysed cyclisation- carbonylation of bromodienes.
- Aggarwal, Varinder K.,Davies, Paul W.,Schmidt, Andreas T.
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- A concise total synthesis of (+)-(6S,9R,10R)-bovidic acid
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A straightforward strategy for the stereoselective synthesis of (+)-bovidic acid has been developed in eleven steps with an overall yield of 8.85%. The synthesis started from commercially available nonanal, and the key reactions involved were Sharpless asymmetric dihydroxylation, Grignard reaction, and Corey-Bakshi-Shibata reduction.
- Wadavrao, Sachin B.,Ghogare, Ramesh S.,Venkat Narsaiah
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Read Online
- Annulation-retro-Claisen cascade of bifunctional peroxides for the synthesis of lactone natural products
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A new and highly efficient annulation-retro-Claisen cascade, which involves the [4 + 1] or [5 + 1] annulation of α-benzoylacetates with bielectrophilic peroxides and a subsequent debenzoylation process under mild basic conditions, has been developed for the rapid construction of valuable tetrahydrofuran- and dihydropyran-2-carboxylates in good yields. By employing the new reaction, the unified total synthesis of γ- and δ-lactone natural products such as (±)-tanikolide, (±)-goniothalamins, (±)-7-epi-goniodiol, and (±)-plakolide A has been accomplished in 4-7 steps.
- Hu, Lin,Li, Jialin,Li, Xuemin,Xu, Qianlan
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supporting information
p. 274 - 277
(2022/01/03)
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- Cobalt-Catalyzed Regio- and Stereoselective Hydroboration of Allenes
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An efficient pincer-ligand-based cobalt-complex-catalyzed allene hydroboration affording Z-allylic boronates is described. The reaction demonstrates an excellent regio- as well as Z-stereoselectivity and a wide substrate scope that tolerates many functional groups. Based on solvent-assisted electrospray ionization mass spectrometry (SAESI-MS) studies, a rationale for the cobalt-catalyzed hydroboration involving the highly selective insertion of an allene into the Co?H bond to form Z-allylic cobalt intermediates is proposed.
- Guo, Yinlong,Huang, Zheng,Li, Can,Ma, Shengming,Wang, Lei,Yang, Zheng
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supporting information
p. 6278 - 6283
(2020/02/25)
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- Enantioselective addition of selenosulfonates to α,β-unsaturated ketones
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An organo-catalyzed enantioselective addition of selenosulfonates to α,β-unsaturated ketones was developed for the first time. With a chiral squaramide as an efficient catalyst, the desired α-selenylated ketones were obtained in a good yields with high enantioselectivity up to 89% ee, and good results could be obtained on a gram scale. The products could also be efficiently transformed into useful building blocks with a propenylic stereocenter; the strategy presented in this study may find further applications in organic synthesis.
- Luo, Shilong,Zhang, Nan,Wang, Zhen,Yan, Hailong
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supporting information
p. 2893 - 2901
(2018/05/03)
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- Borohydride-mediated radical addition reactions of organic iodides to electron-deficient alkenes
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Cyanoborohydrides are efficient reagents in the reductive addition reactions of alkyl iodides and electron-deficient olefins. In contrast to using tin reagents, the reaction took place chemoselectively at the carbon-iodine bond but not at the carbon-bromine or carbon-chlorine bond. The reaction system was successfully applied to three-component reactions, including radical carbonylation. The rate constant for the hydrogen abstraction of a primary alkyl radical from tetrabutylammonium cyanoborohydride was estimated to be 4 M-1 s-1 at 25 °C by a kinetic competition method. This value is 3 orders of magnitude smaller than that of tributyltin hydride.
- Kawamoto, Takuji,Uehara, Shohei,Hirao, Hidefumi,Fukuyama, Takahide,Matsubara, Hiroshi,Ryu, Ilhyong
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p. 3999 - 4007
(2014/05/20)
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- Influence of the chemical structure on odor qualities and odor thresholds in homologous series of alka-1,5-dien-3-ones, alk-1-en-3-ones, alka-1,5-dien-3-ols, and alk-1-en-3-ols
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Odor qualities and odor thresholds in air in homologous series of synthesized alk-1-en-3-ols and alka-1,5-dien-3-ols and their corresponding ketones were evaluated by gas chromatography-olfactometry. In the series of the alk-1-en-3-ols and alk-1-en-3-ones the odor quality changed successively from pungent for the compounds with five carbon atoms via metallic, vegetable-like for the six- and seven-carbon odorants to mushroom-like for the compounds with eight and nine carbon atoms. With further increase in chain length the mushroom-like impression decreased and changed to citrus-like, soapy, or herb-like. In both series, two odor threshold minima were found for the six-carbon and also for the eight- and nine-carbon odorants, respectively. In contrast to this, the odor qualities in the series of the (Z)- and (E)-alka-1,5-dien-3-ols and their corresponding ketones did not change significantly with geranium-like, metallic odors and an increasing mushroom-like odor note with increasing chain length. The lowest thresholds were found for the eight- and nine-carbon (Z)-compounds, respectively.
- Lorber, Katja,Schieberle, Peter,Buettner, Andrea
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p. 1025 - 1031
(2014/03/21)
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- Influence of the chemical structure on odor qualities and odor thresholds in homologous series of alka-1,5-dien-3-ones, alk-1-en-3-ones, alka-1,5-dien-3-ols, and alk-1-en-3-ols
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Odor qualities and odor thresholds in air in homologous series of synthesized alk-1-en-3-ols and alka-1,5-dien-3-ols and their corresponding ketones were evaluated by gas chromatography-olfactometry. In the series of the alk-1-en-3-ols and alk-1-en-3-ones the odor quality changed successively from pungent for the compounds with five carbon atoms via metallic, vegetable-like for the six- and seven-carbon odorants to mushroom-like for the compounds with eight and nine carbon atoms. With further increase in chain length the mushroom-like impression decreased and changed to citrus-like, soapy, or herb-like. In both series, two odor threshold minima were found for the six-carbon and also for the eight- and nine-carbon odorants, respectively. In contrast to this, the odor qualities in the series of the (Z)- and (E)-alka-1,5-dien-3-ols and their corresponding ketones did not change significantly with geranium-like, metallic odors and an increasing mushroom-like odor note with increasing chain length. The lowest thresholds were found for the eight- and nine-carbon (Z)-compounds, respectively.
- Lorber, Katja,Schieberle, Peter,Buettner, Andrea
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p. 1025 - 1031
(2015/04/22)
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- Remote control of regio- and diastereoselectivity in the hydroformylation of bishomoallylic alcohols with catalytic amounts of a reversibly bound directing group
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(Figure Presented) Remote and reversible! Phosphinites serve as reversibly bound directing groups for the remote control of the regio- and diastereoselective hydroformylation of bishomoallylic alcohols (see scheme; r.r: regioisomer ratio). The distance between the double bond and the functional hydroxy group to which the directing group is reversibly bound is the longest ever reported.
- Gruenanger, Christian U.,Breit, Bernhard
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supporting information; experimental part
p. 967 - 970
(2010/05/02)
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- Tin-free giese reaction and the related radical carbonylation using Alkyl iodides and cyanoborohydrides
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Tin-free Giese reaction and the related radical carbonylation process proceeded efficiently in the presence of sodium cyanoborohydride and tetrabutylammonium cyanoborohydride. The reaction took place chemoselectively at the carbon-iodine bond but not at the carbon-bromine and carbon-chlorine bonds. The iodine atom transfer followed by hydride reduction of the resulting carbon-iodine bond is proposed as a possible mechanism.
- Ryu, Ilhyong,Uehara, Shohei,Hirao, Hidefumi,Fukuyama, Takahide
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body text
p. 1005 - 1008
(2009/04/07)
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- Synthesis of Aldehydes by Ozonolysis of Secondary Allyl
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The invention relates to a process for the preparation of an aldehyde from a secondary alcohol having a double bond in the alpha position, comprising the steps. a) provision of the alcohol,b) treatment of the alcohol with ozone.
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Page/Page column 6
(2009/01/24)
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- Novel reductive cleavage reaction of α-halo epoxides with SMI2: Synthesis of cyclopropanols
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Aryl substituted α-halo epoxide reacted with SmI2 to give the cyclopropanols in the presence of HMPA, while allyl alcohols were yielded in the absence of HMPA.
- Park, Heui Sul,Chung, So Hee,Kim, Yong Hae
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p. 1073 - 1074
(2007/10/03)
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- A Convenient Synthesis of the Peach Fruit Moth Carposina Niponensis Walk. and of the Douglas Fir Tussock Moth Orgya Pseudotsugata Mc.D. Sex Pheromones and Analogs
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The (Z)- and (E)-isomers of 7-alken-11-ones with chain lengths of 19, 21 and 23 carbon atoms were synthesized.A procedure based on the reaction of alkenylcopper reagents with vinylketones has been elaborated.
- Ramiandrasoa, F.,Descoins, C.
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p. 1989 - 1999
(2007/10/02)
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- SYNTHESIS OF 1,3-DIOLS: ITS APPLICATION TO THE SYNTHESIS OF α-LIPOIC ACID
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1,3-diols have been prepared from monosubstitited olefins, and the utility of this method in the synthesis of α-lipoic acid has been described.
- Rao, A. V. Rama,Mysorekar, Sudha V.,Yadav, J. S.
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p. 1339 - 1348
(2007/10/02)
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- ISOMERIZATION OF ALLYLIC ALCOHOLS CATALYZED BY VANADIUM OR MOLYBDENUM COMPLEXES.
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Isomerization of primary allylic alcohols proceeds in dichloromethane at 25 degree C in the presence of the catalyst prepared in situ from VO(acac)//2 or MoO//2(acac)//2, and Me//3SiOOSiMe//3 to give tertiary isomers in good yields. The catalysts are also effective for the rearrangements of sec. yields tert. allylic alcohols. The isomerization of an allenyl allylic alcohol, 6-methyl-1,2,5-heptatrien-4-ol, gives either (E)-2-methyl-3,5,6-heptarien-2-ol or (E)-6-methyl-3,5-heptadien-2-one selectively depending on the reaction conditions.
- Matsubara,Okazoe,Oshima,Takai,Nozaki
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p. 844 - 849
(2007/10/02)
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- ISOMERIZATION OF PRIMARY ALLYLIC ALCOHOLS TO TERTIARY ONES BY MEANS OF Me3SiOOSiMe3-VO(acac)2 CATALYST
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The title rearrangement proceeds in dichloromethane at 25 oC in the presence of the catalyst prepared in situ to give tertiary isomers in good yields.Other rearrangements of sec. -> tert. or sec. -> sec. have been examined.
- Matsubara, Seijiro,Takai, Kazuhiko,Nozaki, Hitosi
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p. 3741 - 3744
(2007/10/02)
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- SELECTIVE GRIGNARD-TYPE CARBONYL ADDITION OF ALKENYL HALIDES MEDIATED BY CHROMIUM(II) CHLORIDE
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Alkenyl (or aryl) iodide (or bromide) is readily reduced with CrCl2 in N,N-dimethylformamide at 25oC to give the corresponding organochromium species which adds selectively to an aldehyde moiety without affecting the coexisting ketone or cyano group of the substrate.
- Takai, Kazuhiko,Kimura, Keizo,Kuroda, Tooru,Hiyama, Tamejiro,Nozaki, Hitosi
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p. 5281 - 5284
(2007/10/02)
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