DBU-promoted nucleophilic activation of organic carbonates
The reactivity of carbonic acid diesters in the presence of the amidine base DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) has been investigated for the first time. Organic carbonates can be activated by DBU through the formation of N-alkoxycarbonyl ketene aminal 2 as the ultimate product. The latter spe...
Published in: | European Journal of Organic Chemistry |
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Main Authors: | , , |
Other Authors: | , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
2011
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Subjects: | |
Online Access: | http://hdl.handle.net/11586/134411 https://doi.org/10.1002/ejoc.201001725 http://onlinelibrary.wiley.com/doi/10.1002/ejoc.201001725/pdf |
Summary: | The reactivity of carbonic acid diesters in the presence of the amidine base DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) has been investigated for the first time. Organic carbonates can be activated by DBU through the formation of N-alkoxycarbonyl ketene aminal 2 as the ultimate product. The latter species may form through deprotonation of the corresponding N-alkoxycarbonyl-amidinium cation 1+ by the amidine base. We have for the first time isolated and characterized both in the solid state (X-ray crystal structure determination, IR) and in solution (NMR), a few 1+ chloride salts and studied their reactivity towards the organic base. The reactivity of both 1+ and 2 with methanol has also been explored. Ketene aminal 2 behaves as a “CO2R” carrier, as it can selectively transfer the alkoxycarbonyl group to the alcohol and regenerate the amidine base. |
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