Electrophilic Aromatic Substitutions of Aryltrifluoroborates with Retention of the BF<sub>3</sub><sup>–</sup> Group: Quantification of the Activating and Directing Effects of the Trifluoroborate Group
contrast to common belief, substitutions at CH positions are often faster than ipso-substitutions of the BF3K group, because BF3K activates the position attached to boron by a factor of 10(3)-10(4) while adjacent CH positions are activated by factors of 10(5)-10(6). Several reactions that have previously been interpreted as ipso-substitutions actually proceed via initial substitution at a vicinal or remote