Reactivity and Regiochemical Behavior of the 2,2-Difluorocyclopropylcarbinyl Cation: A New and Improved Mechanistic Probe To Distinguish Radical and Carbocation Intermediates

Acetolysis of 2,2-difluorocyclopropylcarbinyl tosylate ( 5 ) yields products derived from both S N 1 and S N 2 processes. Product identification and kinetic data indicated, as had been predicted computationally, that the cyclopropylcarbinyl−allylcarbinyl cationic rearrangement of 5 occurs simultaneously with its ionization and with regiospecific proximal bond cleavage to give products that formally derive from the 1,1-difluoro-3-butenyl cation with a rate constant that is 8.3 × 10 4 smaller than that of the parent cyclopropylcarbinyl tosylate and 1.8 times larger than isobutyl tosylate at 96.6 °C.