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 kin etic data indicated, as had been predicted computationally, that the cyclop ropylcarbinyl-allylcarbinyl cationic rearrangement of 5 occurs simultaneous ly with its ionization and with regiospecific proximal bond cleavage to giv e products that formally derive from the 1,1-difluoro-3-butenyl cation with a rate constant that is 8.3 x 10(4) smaller than that of the parent cyclop ropylcarbinyl tosylate and 1.8 times larger than isobutyl tosylate at 96.6 degrees C.