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Mechanism of formation of phosphonate carbanions with the use of a lithium salt and 1,8‐diazabicyclo[5.4.0] undec‐7‐ene
Author(s) -
Froment F.,
Corset J.
Publication year - 1990
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.610031108
Subject(s) - chemistry , phosphonate , carbanion , deprotonation , protonation , lithium (medication) , denticity , solvation , salt (chemistry) , medicinal chemistry , carboxylate , photochemistry , solvent , chelation , reaction mechanism , inorganic chemistry , catalysis , ion , organic chemistry , crystal structure , medicine , endocrinology
The deprotonation reaction mechanism of methyl diethylphosphonoacetate in the presence of lithium salts and 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) was examined by infrared spectroscopy. It was found that the intermediate species formed by chelation of the bidentate phosphonate with a lithium cation or an ion pair of the salt deaggregated by DBU takes part in the reaction path. The role of the anion X − is to induce the elimination of a protonated DBUH + X − ion pair and that of the solvent is to compete with the bidentate phosphonate in cation solvation. A similar mechanism via a related intermediate is proposed to interpret the results obtained by other workers on the catalysis by Ba(OH) 2 of the Wittig–Horner reaction.