Fig. 4. (a) Dependence of the changes in activation energy ΔEa for substrate 6 for the favored decarboxylation (ΔEfa, ○) and the disfavored addition (to 8, ΔEda, [black circle]) on the π acidity of anion–π tweezers 13–16 (ELUMO), relative to control 17, at 5 °C, with exponential curve fit (Table 1, entries 10–13). (b) Selective acceleration of a disfavoured reaction: dependence of ΔΔEd–fa, i.e., ΔEda – ΔEfa, for 6 on the π acidity of 13–16 (ELUMO) compared to control 11 ([black circle], ♦, □) or 17 (X) at RT ([black circle], X, □) and 5 °C (♦) for 6 ([black circle], X, ♦) and 7 (□) with 8, with exponential curve fit (compare Table 1).
