- The stereochemical course of bromoetherification of enynes
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Enynes undergo stereoselective syn intramolecular bromoetherification; the stereochemical course of the reaction was elucidated by X-ray crystallographic studies and by stereospecific synthesis of authentic bromoallenes. The Royal Society of Chemistry.
- Christopher Braddock,Bhuva, Roshni,Perez-Fuertes, Yolanda,Pouwer, Rebecca,Roberts, Craig A.,Ruggiero, Andrea,Stokes, Elaine S. E.,White, Andrew J. P.
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p. 1419 - 1421
(2008/12/21)
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- First total synthesis of (-)-ichthyothereol and its acetate
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The first and stereoselective total syntheses of (-)-ichthyothereol (1) and its acetate ((+)-2) were achieved by incorporation of the two chiral centers of diethyl L-tartrate. The starting diethyl L-tartrate was converted into trans-2-ethynyl-3-hydroxytetrahydropyran 14 in a stereoselective manner via the endo mode cyclization of the epoxy-alkyne derivative 12. The alcohol 12 was then transformed into (E)-iodoolefin derivative 15, which was exposed to a coupling reaction with 1-tributylstannyl-1,3,5-heptyne (19), derived from the corresponding 1-trimethylsilyl-1,3,5-heptyne (18), under Stille conditions to produce the all-carbon framework of the target natural products. Chemical modification of the coupled product 20 under conventional conditions completed the first total synthesis of (-)-ichthyothereol (1) and its acetate ((+)-2).
- Mukai,Miyakoshi,Hanaoka
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p. 5875 - 5880
(2007/10/03)
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- A new procedure for highly stereoselective and regioselective synthesis of 2-ethynyl-3-hydroxytetrahydropyran derivatives based on alkyne-Co2(CO)6 complex
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Treatment of trans-epoxides 3 with Co2(CO)8 gave the corresponding cobalt complexes, which were subsequently exposed to a catalytic amount of BF3·OEt2 at -78°C to provide exclusively cis-2-ethynyl-3- hydroxytetrahydropyran derivatives via endo mode cyclization pathway. cis- Congeners, cis-3 afforded the corresponding trans tetrahydropyran derivatives exclusively. This novel cyclization has been found to proceed with retention of configuration at the propynyl stereogenic center. Requirement for stereoselectivity in cyclization was discussed.
- Mukai, Chisato,Sugimoto, Yu-Ichi,Ikeda, Yoshitaka,Hanaoka, Miyoji
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p. 823 - 850
(2007/10/03)
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