Isosterism electronic parameters

For example, substitution of the vinyl sulfone 13 by primary, secondary, and teriary amines (equation 3) obeys a single equation (equation 4) (56), where 2a is the sum of the inductive effects of the amine substituents, and En is an isosteric parameter where the steric effect of an amine R1R2NH is taken as similar to Es of CHR 2. Twenty-two amines obeyed the equation with p = —4.8 and 8 = 1.70 where p and 8 are the sensitivity parameters to the inductive and steric effects, respectively. As a demonstration of the electronic effects, fccyciohexyUmin Aniline 10 in sPite of their similar size, whereas steric effects are reflected in the Et2NH i-Pr2NH °f approximately 3000 in spite of the similar basicities. Similar LFERs were observed in other reactions (Table IX) (29). 

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