- Use of Sulfoxides as Cocatalysts in the Palladium-Quinone-Catalyzed 1,4-Diacetoxylation of 1,3-Dienes. An Example of Ligand-Accelerated Catalysis
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The use of sulfinyl quinones as cocatalysts in the palladium-catalyzed 1,4-diacetoxylation of 1,3-dienes improves the stereochemical outcome of the reaction by increasing the rate of the internal migration of the acetate nucleophile.A mechansim of the int
- Grennberg, Helena,Gogoll, Adolf,Baeckwall, Jan-E.
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p. 5808 - 5811
(2007/10/02)
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- Synthesis of the cis-3a,8b-Dihydrofurobenzofuran-2(3H)-one Ring System via a Furofuran Annulation to Activated Benzoquinones
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The uncatalysed addition of 2-(trimethylsiloxy)furan (4) to the 1,4-benzoquinones (5a-e) containing electron-withdrawing groups at C-2 gave the cis-3a,8b-dihydrofurobenzofuran-2(3H)-ones (6a-e) in 51-76percent yields.The 1,4-benzoquinones (5f, g, h) without electron-withdrawing groups at C-2 failed to undergo the furofuran annulation, with none of the desired adducts (6f, g, h) being isolated.The carboxylic acid adduct (6i; R=CO2H) was prepared indirectly by reductive hydrolysis of either the phenacyl adduct (6e) or the trichloroethyl ester adduct (6d) using zinc in acetic acid (9).Treatment of the methyl ketone adduct (6b) with acid effected a ring opening to the corresponding (benzofuran-2-yl)acetic acid.
- Brimble, Margaret A.,Brimble, Mark T.,Gibson, Jennifer J.
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p. 179 - 184
(2007/10/02)
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- 1,4-ADDITION OF 2-TRIMETHYLSILYLOXYFURAN TO QUINONES: A FACILE ROUTE TO THE FUROBENZOFURAN NUCLEUS
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The uncatalysed addition of 2-trimethylsilyloxyfuran (3) to a range of activated quinones (4) and (6) yields the crystalline adducts (5) and (7) in 51-91percent yield.This novel furofuran-annulation to a quinone system provides a facile entry to the furobenzofuran ring system.
- Brimble, Margaret A.,Gibson, Jennifer J.,Baker, Raymond,Brimble, Mark T.,Kee, Alex A.,O'Mahony, Mary J.
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p. 4891 - 4892
(2007/10/02)
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