Beckman and Munshi reports a reversible CO2 carrier (RCC) for the 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.
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Ambient carboxylation on a supported reversible CO2 carrier: ketone to β-keto ester, Eric J. Beckman and Pradip Munshi, Green Chem., 2011, DOI: 10.1039/C0GC00704H, Advanced Article, Paper
