Phenanthrenes automerization

Balaban et a/. have reported the catalytic automerization of [1- C]- or [3- C]-phenanthrene in the presence of a 1 1 mixture of AlCh-NaCl. They found that [l- C]phenanthrene transferred part of the label to C-3, but [3- C]phenanthrene transferred the label to two positions, i.e. mainly C-1 and to a lesser extent C-4, as shown in Scheme 16. Possible reaction mechanisms to account for these observations were also proposed. 

---