Camphene Rearrangements

intramolecular rearrangements of compounds of the terpene series. Camphene rearrangements of the first and second types are known. Mutual transformations of terpenes during the camphene rearrangements are analogous to the retrograde pinacol-pinacoline rearrangement in the aliphatic series. Thus, dehydration of borneol in the presence of acids leads not to the expected unsaturated hydrocarbon (bornylene) but rather to its structural isomer (camphene) as a result of a camphene rearrangement of the first type. The industrial synthesis of camphor from alpha-pinene also includes a camphene rearrangement of the first type.

Camphene rearrangements of the first type were discovered by E. Vagner (1899), and H. Meerwein subsequently studied their mechanism. Camphene rearrangements of the second type were discovered in 1927 by S. Nametkin. For this reason, camphene rearrangements of the first type are frequently called Vagner or Vagner-Meerwein rearrangements, and rearrangements of the second type are known as Nametkin rearrangements.