- Lewis acid/CpRu dual catalysis in the enantioselective decarboxylative allylation of ketone enolates
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The addition of a Lewis acidic metal triflate salt Mg(OTf)2 as co-catalyst in the CpRu-catalyzed decarboxylative allylation of in situ-generated ketone enolates allows the reaction to proceed at lower temperature with higher regio- and enantios
- Linder, David,Austeri, Martina,Lacour, Jerome
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supporting information; experimental part
p. 4057 - 4061
(2009/12/06)
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- Olefin-Methathese. XXII. Metathese von carbonyl-geschuetztem Allylaceton mit Monoolefinen an zinnalkylaktiviertem Re2O7/Al2O3
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Olefin metathesis of allylacetone usually proceeds with little conversion.After the carbonyl group is protected by (i) silylation with ClSi(CH3)3 to give silylenolethers or (ii) by acetalisation with 1,2-ethanediol to the 1,3-dioxane derivative the reactivity increases significantly in the homometathesis reaction as well as in the co-metathesis with mono-olefins.Using Re2O7/Al2O3 + Sn(CH3)4 as catalyst the metathesis of allylacetone as its silylenolether or as 1,3-dioxolane proceeds with conversions of 46-53percent while the reaction of unprotected ketone only leads to a conversion of 14percent.Co-metathesis with the double-molar amount of symmetrical internal olefins (4-octene, 5-decene, 7-tetradecene, 9-octadecene) 75-90percent of the protected ketone is converted to give mainly the chain-prolonged silylenolethers or the 1,3-dioxolanes.Allylacetone silylated on a preparative scale was subjected to co-metathesis with 4-octene using MoO3-Re2O7/Al2O3 + Sn(CH3)4 as catalyst.After elimination of the protecting group the perfume substance 5-nonene-2-one was obtained in 61percent yield.
- Warwel, Siegfried,Puetz, Gabriele
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p. 323 - 330
(2007/10/02)
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