Synthesis and Characterization of Novel Quinone Methides: Reference Electrophiles for the Construction of Nucleophilicity Scales

Eur. J. Org. Chem., 2009, 3293-3211 published on 14.05.2009
Eur. J. Org. Chem. 2009
Novel synthetic routes to the aryl-substituted quinone methides 3a–f have been developed, and a previously reported Mannich approach has been used for the syntheses of the acceptor substituted quinone methides 2e–g. The secondorder rate constants for the reactions of 3c–f and 2e–g with the carbanions 9a–h were determined photometrically in DMSO. With Equation (1), logk2 = s (N + E), and the known nucleophilicity parameters N and s for the carbanions 9a–h, it was possible to calculate the electrophilicity parameters E for these quinone methides. With E parameters between –12 and –17, these readily accessible quinone methides are recommended as reference electrophiles for the construction of nucleophilicity scales. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
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