- Grignard reagents: Alkoxide-directed iodine-magnesium exchange at sp 3 centers
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(Chemical Equation Presented) Sequential addition of i-PrMgCl and BuLi to sp3 hybridized iodoalcohols triggers a facile iodine-metal exchange. Intercepting the resulting cyclic Grignard reagents with a slight excess of an electrophile leads to a diverse range of substituted alcohols. The iodine-magnesium exchange strategy is effective with 3-carbon iodoalcohols bearing alkyl substitutents on the carbinol or adjacent carbons and with the chain-extended homolog 4-iodobutan-1-ol.
- Fleming, Fraser F.,Gudipati, Subrahmanyam,Vu, Viet Anh,Mycka, Robert J.,Knochel, Paul
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p. 4507 - 4509
(2008/03/11)
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- The study of intramolecular tandem radical cyclizations of acylsilanes with radicalphiles attached on silicon
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Radical cyclizations of acylsilanes with radicalphilic pendant introduced on silicon proceeded in a tandem fashion to give spiro products containing a cyclic silyl ether skeleton. Because the alkoxysilyl group can be replaced with a hydroxy group through
- Tang, Kuo-Hsiang,Liao, Fang-Yu,Tsai, Yeun-Min
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p. 2037 - 2045
(2007/10/03)
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- An advanced intermediate for the synthesis of (±)-pumiliotoxin C and its analogues
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Compound 1 as a versatile intermediate for the synthesis of (±)-pumiliotoxin C and its analogues was prepared from commercially available cyclohexanone. The key step in the synthesis was the construction of octahydroquinoline ring by a stereoselective ami
- Shao, Zhi-Hui,Peng, Fang-Zhi,Chen, Jing-Bo,Wang, Chen-Ying,Huang, Rong,Tu, Yong-Qiang,Li, Liang,Zhang, Hong-Bin
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p. 2031 - 2038
(2007/10/03)
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- 3-chloropropyl and 4-chlorobutyl phenyl ethers as sources of 1,3-dilithiopropane and 1,4-dilithiobutane: Sequential reaction with carbonyl compounds
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The reaction of 3-chloropropyl and 4-chlorobutyl phenyl ethers (1) with lithium powder and a catalytic amount of DTBB (5% molar) in THF at - 78 °C followed by successive treatment with a carbonyl compound [R1R2CO = ButCHO, Me2CO, (CH2)5CO, (-)-menthone] at -78 to 20 °C and, after 1.5 h at this temperature, with a second one [R3R4CO = Bu1CHO, PhCHO, Me2CO, MeCOPrn, (CH2)5CO, (-)-menthone] at -78 °C leads, after hydrolysis with water, to the corresponding 1,5-and 1,6-diols (2). Because of the competition of two different reductive cleavages, 1,4- and 1,5-diols 3 were also obtained as side-reaction products.
- Foubelo, Francisco,Saleh, Sadiq A.,Yus, Miguel
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p. 3478 - 3483
(2007/10/03)
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- Group transfer from silicon to carbon via tandem radical cyclizations of acylsilanes
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Tandem radical cyclizations of acylsilanes with alkene or alkyne functionalities attached to silicon afforded cyclic silyl ethers which were oxidatively hydrolyzed to give diols or ketone alcohols.
- Tsai, Yeun-Min,Tang, Kuo-Hsiang,Jiaang, Weir-Torn
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p. 7767 - 7770
(2007/10/03)
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- General Synthesis of 1-Oxaspirodecan-2-ones and 1-Oxaspirodecanes from 5-Methylene-2(5H)-furanone
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5-Methylene-2(5H)-furanone underwent Diels-Alder cycloadditions to butadiene and several acyclic and cyclic C-substituted dienes, respectively, affording bicyclic and tricyclic spiroadducts in good yields.These compounds are precursors of other unsaturated and saturated spirolactones and also spiroethers, which were obtained through simple chemical reactions, i.e., hydrogenation of C-C double bonds, reduction of the carbonyl group, and Michael addition.The synthesis of 32 spirolactones and eight spiroethers illustrates the scope and efficiency of this method.Many of these products are suitable for use as components of perfumes and aromas owing to their olfactive properties.
- Alonso, Daniel,Font, Josep,Ortuno, Rosa M.
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p. 5567 - 5572
(2007/10/02)
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- γ-Lithioalkoxides via Reductive Lithiation of Oxetanes by Aromatic Radical Anions
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Oxetanes are cleaved at 0 deg C in tetrahydrofuran by lithium 4,4'-di-tert-butylbiphenylide, giving lithium γ-lithioalkoxides which can provide 2-substituted tetrahydrofurans by trapping with aldehydes and ketones followed by acid cyclization of the resulting 1,4-diols; the cuprates of these dianions undergo conjugate addition and nucleophilic substitution reactions.
- Mudryk, Boguslaw,Cohen, Theodore
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p. 5657 - 5659
(2007/10/02)
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- SYNTHESE DE COMPOSES DIHYDRO-2,3 FURANNIQUES PAR HYDROBORATION D'ALCOOLS β-ACETYLENIQUES
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Hydroboration of β acetylenic alcohols followed by NaOH/H2O2 oxidation leads to hemiacetals of γ aldols which are easily dehydrated to 2,3-dihydrofuran compounds.The reaction gives good yields with hindered alcohols and its stereochemistry may be controlled during the organometallic synthesis of the starting alcohol.
- Dana, Gilbert,Figadere, Bruno,Touboul, Estera
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p. 5683 - 5684
(2007/10/02)
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- TRANSFORMATION OF ALLYLIC EPOXIDES TO TETRAHYDROFURFURYL ALCOHOLS VIA HYDROBORATION
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The allylic epoxides (1)-(4) were transformed to the tetrahydrofurfuryl alcohols (17)-(20), respectively.The formation of (6) and (10) in the hydroboration-oxidation of (4) is interpreted.The monohydroboration-oxidation of (13) and (14) gave (15) and (16), respectively.
- Zaidlewicz, Marek,Sarnowski, Ryszard
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p. 281 - 284
(2007/10/02)
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- One-Step Annelation. A Convenient Method for the Preparation of Diols, Spirolactones, and Spiroethers from Lactones
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1-(ω-Hydroxyalkyl)cyclopentanols and -cyclohexanols were prepared in one step in high yields from butane-1,4-diyl- and pentane-1,5-diylmagnesium dibromides and lactones in tetrahydrofuran.This method was found to be general and applicable to lactones of any size (β, γ, δ, and ε) and structure whether aliphatic, aromatic, bicyclic, or spirocyclic.Evidently important steric hindrance close to the carbonyl group prevents annelation and attack on the second nucleophilic center of the Grignard reagent.Furthermore, in the case of oxetan-2-one one obtains, in additionto the corresponding diol, products resulting from scission of the C-O bond.The diols by appropriate transformation afford new routes to spirolactones and spiroethers.
- Canonne, Persephone,Foscolos, Georges B.,Belanger, Denis
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p. 1828 - 1835
(2007/10/02)
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