The rates of the reactions of the colored para-substituted phenylacetonitrile anions 1a−c and the phenylpropionitrile anions 2a−c with Michael acceptors (3a−u) were determined by UV−vis spectroscopy in DMSO at 20 °C. The reactions follow second-order kinetics, and the corresponding rate constants k2 obey the linear-free-energy relationship log k2(20 °C) = s(N + E), from which the nucleophile-specific
Pushing the Upper Limit of Nucleophilicity Scales by Mesoionic <i>N</i>‐Heterocyclic Olefins
作者:Andreas Eitzinger、Justus Reitz、Patrick W. Antoni、Herbert Mayr、Armin R. Ofial、Max M. Hansmann
DOI:10.1002/anie.202309790
日期:2023.10.2
series of mesoionic N-heterocyclic olefins (mNHOs) was synthesized and their reactions with Michael acceptors and CO2 investigated. The outstandingly high nucleophilicities of mNHOs were determined by kinetic measurements and located on the Mayr scale where they belong to the strongest carbon nucleophiles reported to date.
Determination of the Electrophilicity Parameters of Diethyl Benzylidenemalonates in Dimethyl Sulfoxide: Reference Electrophiles for Characterizing Strong Nucleophiles
作者:Oliver Kaumanns、Roland Lucius、Herbert Mayr
DOI:10.1002/chem.200801277
日期:2008.10.29
second-order rate constants of the reactions of nine substituted diethyl benzylidenemalonates 1 a-i with the carbanions 2 a-e have been determined spectrophotometrically in dimethyl sulfoxide (DMSO). Product studies show that the nucleophiles attack regioselectively at the electrophilic C==C double bond of the Michael acceptors to form the carbanionic adducts 4. The correlation log k(20 degrees C)=s(N+E) allows