- Ambient carboxylation on a supported reversible CO2 carrier: Ketone to β-keto ester
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A reversible CO2 carrier (RCC) has been developed to perform carboxylation of ketone to β-ketoester under ambient CO2 pressure and temperature. RCC has been synthesized by immobilizing 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) on methylhydrosiloxane support and reacting with CO2 with 100% degree of functionalisation. RCC is found to be recyclable and shows retention of activity in 5 recycles. CO2 absorption under ambient temperature and desorption at 120°C renders the material suitable for carrying out carboxylation reactions at 25°C with excellent yields. The yield of the reaction can reach up to 100% with TON 200 in 4 h. The extent of the reaction primarily depends upon enol content of the substrate. β-Ketoacid produced during the reaction can be isolated and converted to its corresponding methyl ester derivative by reacting with methyl iodide.
- Beckman, Eric J.,Munshi, Pradip
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experimental part
p. 376 - 383
(2011/04/17)
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- Method for preparing chiral diphosphines
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The invention concerns a method for preparing a compound of formula (1) wherein: A represents naphthyl or phenyl optionally substituted; and Ar1, Ar2independently represent a saturated or aromatic carbocyclic group, optionally substituted.
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- Asymmetric hydrogenation method of a ketonic compound and derivative
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The present invention relates to a process for the asymmetric hydrogenation of a ketonic compound and derivative. The invention relates to the use of optically active metal complexes as catalysts for the asymmetric hydrogenation of a ketonic compound and derivative. The process for the asymmetric hydrogenation of a ketonic compound and derivative is characterized in that the asymmetric hydrogenation of said compound is carried out in the presence of an effective amount of a metal complex comprising as ligand an optically active diphosphine corresponding to one of the following formulae: STR1
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- Cycloaddition of cross-conjugated trienes to halogenated quinones
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The chemoselectivity of [4+2] cycloadditions involving electron-rich cross-conjugated trienes and halogenated quinones has been examined. The approach provides improved preparations of 6-acetyl-2,3,7-trihydroxyjuglone, solorinic and norsolorinic acids, and averythrin. It also confirms the structure proposed for haematommone and 3,8-dihydroxy-4-methoxy-2-methoxycarbonyl-1-methylanthraquinone but invalidates that of sopheranin.
- Couturier,Brassard
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p. 703 - 708
(2007/10/02)
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