- Copper-Catalyzed Formation of α-Alkoxycycloalkenones from N-Tosylhydrazones
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The combination of 20 mol % of copper iodide and lithium tert-butoxide triggers the formation of a broad range of substituted, functionalized α-alkoxy 2H-naphthalenones from readily available N-tosylhydrazones. The data suggests that this transformation occurs through cycloaddition of a copper carbenoid with an ester, followed by a Lewis acid-catalyzed [1,2] alkyl shift of the in situ generated alkoxyepoxide intermediate. The combination of 20 mol % of copper iodide and lithium tert-butoxide triggers the formation of a broad range of substituted, functionalized α-alkoxy 2H-naphthalenones from readily available N-tosylhydrazones. The reaction proceeds by the cycloaddition of a copper carbenoid with an ester, and a subsequent Lewis acid-catalyzed [1,2] alkyl shift of the in situ generated alkoxyepoxide intermediate.
- Su, Naijing,Theorell, Juliana A.,Wink, Donald J.,Driver, Tom G.
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p. 12942 - 12946
(2015/11/02)
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- Development of a bio-inspired acyl-anion equivalent macrocyclization and synthesis of a trans-resorcylide precursor
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(Chemical Equation Presented) Studies on the macrocyclization of α,ω-dialdehydes have revealed a strong dependence on ring size with respect to the ultimate efficiency of the reaction. Strong catalyst dependence was observed, as thiazolium salts led to no detectable product formation, whereas electron-deficient triazolium salts served as precatalysts for the cyclization. Surprisingly, the N-pentafluorophenyl triazolium variant led to cyclization at room temperature within a short 90-min reaction time. These findings were applied to a range of substrates, including the synthesis of a key intermediate in a rapid synthesis of trans-resorcylide.
- Mennen, Steven M.,Miller, Scott J.
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p. 5260 - 5269
(2008/02/07)
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- Benzannulated cyclooctanol derivatives by samarium diiodide induced intramolecular carbonyl-alkene coupling - Scope, limitations, stereoselectivity
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A series of γ-oxo esters 27-34 was prepared from methyl 2-silyloxycyclopropanecarboxylates 1-9 as key building blocks in a flexible modular synthesis. Their samarium diiodide promoted cyclization to benzannulated cyclooctanol derivatives was systematicall
- Reissig, Hans-Ulrich,Khan, Faiz Ahmed,Czerwonka, Regina,Dinesh, Chimmanamada U.,Shaikh, Aarif L.,Zimmer, Reinhold
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p. 4419 - 4428
(2007/10/03)
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- Preparation of oxocanes by electrophilic cyclizations of unsaturated alcohols in the presence of bis(collidine)halonium(I) hexafluorophosphates
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7-Octen-1-ols substituted in the sp3-sp3 carbon chain with carbocyclic (phenyl and cyclopropane) and heterocyclic (epoxide and dioxolane) moieties were prepared and their cyclizations in the presence of bis(collidine)iodonium(I) and-bromonium(I) hexafluorophosphates as electrophiles were studied. Oxocanes were obtained in modest to good yields when a rigid cyclic moiety (cyclopropane or phenyl) was present in the chain, while yields of cyclizations were lower if the cyclic component had a certain flexibility (dioxolane). Low yields were obtained with substrates bearing an epoxide substituent, probably because of stability problems due to the presence of collidine. With the vinylcyclopropane alcohol 12 we observed mainly the opening of the cyclopropane ring and the cyclization produced a tetrahydropyran derivative. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Mendes, Christelle,Renard, Sylvie,Rofoo, Mazin,Roux, Marie-Claude,Rousseau, Gerard
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p. 463 - 471
(2007/10/03)
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- A Novel Sm(II)-Induced Route to Highly Substituted Benzannulated Cyclooctanol Derivatives
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Siloxycyclopropane derivatives 3 with a suitable styrene side chain can effectively be ring opened to precursors 2 which undergo reductive ring closure with SmI2 to furnish benzannulated cyclooctanols 1 or lactones 7 derived thereof. Tricyclic
- Khan, Faiz Ahmed,Czerwonka, Regina,Zimmer, Reinhold,Reissig, Hans-Ulrich
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p. 995 - 997
(2007/10/03)
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