- Ligand-controlled cobalt-catalyzed remote hydroboration and alkene isomerization of allylic siloxanes
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The Co-catalyzed remote hydroboration and alkene isomerization of allylic siloxanes were realized by a ligand-controlled strategy. The remote hydroboration with dcype provided borylethers, while xantphos favored the formation of silyl enol ethers.
- Huang, Jiaxin,Li, Jie,Yang, Wen,Zhang, Kezhuo,Zhao, Pei,Zhao, Wanxiang
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supporting information
p. 302 - 305
(2022/01/03)
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- Nucleophilic ring-opening of epoxide and aziridine acetates for the stereodivergent synthesis of β-Hydroxy and β-Amino γ-Lactams
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A highly regio- and stereoselective synthesis of novel β,γ- disubstituted γ-lactams with either an anti or syn relative configuration was developed from readily available epoxide and aziridine acetates. The key steps include the regio- and diastereocontrolled nucleophilic ring-opening of these three-membered heterocycles followed by mild reductive cyclization of the γ-azido ester intermediate. The method was also extended to an asymmetric synthesis of (4R,5S)-4-hydroxy-5-phenylpyrrolidin-2-one from a chiral epoxide acetate. The main features of this versatile synthesis of functionalized γ-lactams include the involvement of inexpensive reagents and mild conditions together with high chemical efficiency.
- Bisol, Tula B.,Bortoluzzi, Adailton J.,Sa, Marcus M.
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experimental part
p. 948 - 962
(2011/04/12)
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- Model studies of the overall 5-endo-trig iodocyclization of homoallylic alcohols
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Overall 5-endo-trig iodocyclizations of homoallylic alcohols, with a range of substitution patterns, leading to β-iodotetrahydrofurans are usually highly efficient and stereoselective when carried out in anhydrous acetonitrile in the presence of sodium hydrogen carbonate. Such cyclizations, which are not exceptions to Baldwin's rules as they are electrophile-driven, appear to proceed via a well-ordered chair-like transition state. The iodine can be replaced by hydroxy, acetoxy and azide groups.
- Bedford, Simon B.,Bell, Kathryn E.,Bennett, Frank,Hayes, Christopher J.,Knight, David W.,Shaw, Duncan E.
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p. 2143 - 2153
(2007/10/03)
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- Friedel-Crafts alkylation of benzene and toluene with olefinic C6 hydrocarbons and esters
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To assist our study of the reaction of toluene and other aromatic compounds with methyl oleate and other olefinic esters, benzene and toluene have been alkylated under Friedel-Crafts conditions with hex-1-ene, hex-3-ene, methyl hex-3-enoate and methyl hex-3-enedioate. The products were isolated and identified by NMR and mass spectrometric procedures.
- Black, Kenneth D.,Gunstone, Frank D.
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- Regiochemical control of the ring opening of 1,2-epoxides by means of chelating processes.11. Ring opening reactions of aliphatic mono- and difunctionalized cis and trans 2,3- and 3,4-epoxy esters
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The regiochemical outcome of the ring opening of 1,2-epoxides through chelation processes assisted by metal ions, was verified in the azidolysis of simple aliphatic cis and trans 2,3- and 3,4-epoxy esters and in the corresponding derivatives bearing an ether functionality (OBn) in an allylic relationship to the oxirane ring. The results indicate that the behavior of these epoxides is influenced both by the opening conditions (standard or metal-assisted) and the promoting metal salt [LiClO4 or Mg(ClO4)2]. Copyright
- Azzena, Francesca,Crotti, Paolo,Favero, Lucilla,Pineschi, Mauro
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p. 13409 - 13422
(2007/10/02)
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- Studies Towards the Synthesis of Obtusenyne. A Claisen Rearrangement Approach to Unsaturated Nine-membered Lactones.
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An advanced intermediate for the synthesis of the Laurencia oxonane natural product obtusenyne 1, namely the unsaturated nine-membered lactone 3, was efficiently prepared in seven steps from (E)-3-hexenoic acid 7.The key transformation was the Claisen rearrangement of the vinyl ketene acetal 4, which represents novel methodology for the preparation of such unsaturated nine-membered lactones. Key words: medium ring; unsaturated lactone; Claisen rearrangement; vinyl ketene acetal; selenoxide elimination.
- Curtis, Neil R.,Holmes, Andrew B.,Looney, Mark G.
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p. 7171 - 7178
(2007/10/02)
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- CC-KUPLUNGEN VON CO2 MIT 1,3-DIENEN AN EISEN(0)-KOMPLEXEN; CARBOXYLATBILDUNG UND FOLGEREAKTIONEN
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1,3-Dienes react with CO2 at ligand-iron(0) systems to η3-allyl carboxylates.The dynamic allylic system is influenced by addition of further ligands such as phosphanes or maleic acid anhydride or acetic acid anhydride.The direction of this infl
- Hoberg, Heinz,Jenni, Klaus
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p. 193 - 202
(2007/10/02)
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- SELECTIVE REDUCTION OF α,β-UNSATURATED ESTERS IN THE PRESENCE OF OLEFINS
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Several α,β-unsaturated esters containing also isolated olefins or other functionalities subject to saturation were selectively reduced to the corresponding saturated esters by magnesium in methanol.
- Hudlicky, T.,Sinai-Zingde, G.,Natchus, M. G.
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p. 5287 - 5290
(2007/10/02)
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- EFFECTIVE HYDROGENATION OF CARBON-CARBON TRIPLE BONDS BY NaBH4/PdCl2 IN POLYETHYLENE GLYCOL/CH2Cl2: USEFULNESS OF PEG IN SYNTHETIC REACTIONS
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The NaBH4-PdCl2-polyethylene glycol-CH2Cl2 system has been found to be effective for the hydrogenation of carbon-carbon triple bonds to the corresponding cis-alkenes.
- Suzuki, N.,Kaneko, Y.,Tsukanaka, T.,Nomoto, T.,Ayaguchi, Y.,Izawa, Y.
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p. 2387 - 2392
(2007/10/02)
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- Lithium/Ammonia Reductions of 2-Thiophenecarboxylic Acids
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Lithium/ammonia reductions of 2-thiophenecarboxylic acids (1) in the absence of a proton source afforded mixtures of products.In the presence of methanol acyclic mercapto carboxylic acids (4) were the major products.Ring closure of 4 to the corresponding thiolactones (12) showed the double bonds in 4 to be of cis geometry.Attempts were made to prepare Z olefinic compounds derived from these mercapto carboxylic acids.Lithium 2-thiophenecarboxylate salts (2) afforded good yields of the corresponding 2,5-dihydro-2-thiophenecarboxylic acids (3).The presence of substituents on the ring and the ratio of metal to acid were significant factors in determining the nature of this products.A mechanism is proposed to explain the products observed.
- Blenderman, Walter G.,Joullie, Madeleine M.,Preti, George
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p. 3206 - 3213
(2007/10/02)
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- Selective Reactions in Polyethylene Glycol. Hydrogenation of Acetylenes by NaBH4-PdCl2 in Polyethylene Glycol-Methylene Dichloride
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The NaBH4-PdCl2-polyethylene glycol-CH2Cl2 system has been found to be effective for the hydrogenation of acetylenic triple bonds to the corresponding cis-alkenes.
- Suzuki, Nobutaka,Tsukanaka, Tsuneaki,Nomoto, Tateo,Ayaguchi, Yasuo,Izawa, Yasuji
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p. 515 - 516
(2007/10/02)
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