Nucleophilicity Parameters of Arylsulfonyl-Substituted Halomethyl Anions

作者：Li Zhen; Chen Quan; Mayer Peter; Mayr Herbert^*

来源：Journal of Organic Chemistry, 2017, 82(4): 2011-2017.

DOI：10.1021/acs.joc.6b02844

The rates of the reactions of the arylsulfonyl-substituted carbanions carrying a-chloro and a-bromo substituents (1a-e) with quinone methides 2a-g and benzylidenemalonates 2h and 2i in DMSO were determined photometrically at 20 degrees C. The reactions were performed under pseudo-first-order conditions, and the second-order rate constants were obtained as the slopes of the plots of the pseudo-first-order rate constants versus the concentrations of the reactants used in excess. The second order rate constants correlate linearly with the parameters E of the reference electrophiles according to the linear free energy relationship log k(2)(20 degrees C) = s(N)(N + E), which allowed us to derive the nucleophile-specific parameters N and s(N) of carbanions la-e. The resulting nucleophilicity parameters N (23 < N < 29) reveal the title compounds to be among the most reactive nucleophiles so far integrated on our comprehensive nucleophilicity scale.

• 出版日期2017-2-17