ORGN 10 |
| Carbon Dioxide is a useful carbon resource in synthetic organic chemistry. We have investigated the insertion of CO2 into allene using Ni(cod)2. When a THF solution of allene, Ni(cod)2 (1 equiv) and DBU (2 equiv) was stirred under an atmosphere of CO2 at 0 °C and then to this solution was added PhCHO and the solution was stirred at room temperature, carboxylic acid methyl ester was obtained in good yield after treatment with CH2N2. In this reaction, CO2 was incorporated into the central carbon of allene. The crude carboxylated product was treated with PPTS to give alpha-methylene gamma-lactone. This reaction was further extended to the intramolecular reaction. Thus, compound having allene and aldehyde moieties in a tether was treated in a similar manner to afford bicyclic lactone in high yield. In a similar manner, incorporation of CO2 into allenylsilane afforded allylsilane having a carboxyl group in a highly regio- and stereoselective manner.
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Allenes in Synthesis
8:00 AM-12:00 PM, Sunday, 26 March 2006 Georgia World Congress Center -- C303/304/305, Oral
Division of Organic Chemistry |