Résumé

Competition expts. have been performed to det. the rates, relative to benzene, with which anisole, the three dimethoxybenzenes and the three trimethoxybenzenes are deprotonated by sec-butyllithium. Only the first substituent (anisole relative to benzene) has a strong effect (krelf 2800); the second one accelerates moderately at best (1,3-dimethoxybenzene relative to anisole: krelf 12). Methoxy groups being located para with respect to the metalation site or occupying a vicinal position to another methoxy substituent diminish the reactivity by up to two powers of ten (relative to anisole). These surprising findings are without precedence. [on SciFinder (R)]

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