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DBU‐Promoted Nucleophilic Activation of Carbonic Acid Diesters
Author(s) -
Carafa Marianna,
Mesto Ernesto,
Quaranta Eugenio
Publication year - 2011
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201001725
Subject(s) - chemistry , amidine , deprotonation , aminal , reactivity (psychology) , ketene , organic base , medicinal chemistry , nucleophile , methanol , base (topology) , carbonic acid , tautomer , organic chemistry , stereochemistry , catalysis , medicine , ion , mathematical analysis , alternative medicine , mathematics , pathology
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 “CO 2 R” carrier, as it can selectively transfer the alkoxycarbonyl group to the alcohol and regenerate the amidine base.