- Efficient and stereoselective synthesis of allylic ethers and alcohols
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(Chemical Equation Presented) A short and efficient synthesis of allylic TBS ethers and allylic alcohols has been developed, based upon a unique Kocienski-Julia olefination reaction. Allylic alcohols and allylic ethers are obtained in good to excellent yields and with high (E)-selectivity. The conditions are mild and the procedure is broadly applicable.
- Pospisil, Jiri,Marko, Istvan E.
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p. 5983 - 5986
(2007/10/03)
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- Asymmetric synthesis of thietanose
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Syntheses of optically active thietanose, (2R,3R,4R)-4-acetoxymethyl-3-(tert-butyldimethylsilyl)oxy-2-ethoxythietane (6) and (2R,3R,4R)-3-(tertbutyldimethylsiIyl)oxy-4-[(/m-butyldimethylsilyl)oxy]methyl-2- ethoxythietane (23) are described. The key interm
- Uenishi, JuN'Ichi,Motoyama, Mitsuhiro,Kimura, Yumi,Yonemitsu, Osamu
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p. 439 - 451
(2007/10/03)
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- Regiochemical control of the ring opening of 1:2-epoxides by means of chelating processes. 10. Synthesis and ring opening reactions of mono- and difunctionalized cis and trans aliphatic oxirane systems
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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 mono- and difunctionalized aliphatic oxirane systems bearing the heterofunctionality (OR) in an homoallylic and/or allylic relationship to the oxirane ring. The effect of the distance of the OR functionality from the oxirane ring and of the type of protective group on the regiochemical outcome of these systems is examined. In some cases, the use of LiClO4 or Mg(ClO4)2 as the promoting metal salt makes it possible the obtainment of a nice regioalternating process.
- Azzena, Francesca,Calvani, Federico,Crotti, Paolo,Gardelli, Cristina,Macchia, Franco,Pineschi, Mauro
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p. 10601 - 10626
(2007/10/02)
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- An Access to erythro-Diols via Sharpless's Asymmetric Dihydroxylation Reaction
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A method has been developed to access erythro-2,3-diols via Sharpless's asymmetric dihydroxylation reaction.Thus, a TBDMS-protected (E)-allylic alcohol is dihydroxylated and the resulting threo-2,3-diol is converted to the cyclic sulfate.Upon desilylation, this compound undergoes a Payne-type rearrangement.Nucleophilic epoxide-opening then provides an erythro-2,3-diol.The conversions from the cyclic sulfate to the diol product are performed in a single reaction vessel.Due to the irreversible nature of the Payne-type rearrangement, this process is easy to perform and completely regioselective independent of the substrate structures.Also, being performed in THF, the process is compatible with a variety of nucleophiles, including thiolates, -N3, -OAc, -CN, halides as well as carbon nucleophiles and hydride.
- Ko, Soo Y.,Malik, Majbeen,Dickinson, A. Frances
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p. 2570 - 2576
(2007/10/02)
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