Information on the mechanism of the cytochrome-P-450-catalyzed allylic oxidation is limited to two fundamental studies by Groves and Suhramanian [I] and Nelson and coworkers [ 2 ] . In the cases investigated, cyclic substrates were oxidized by microsomal P-450 to yield considerable amounts of stereochemically scrambled products, indicating that the ally1 radical, presumably formed as an intermediate, is unexpectedly prone to allylic rearrangement faster than being trapped by the hydroxyl radical delivered from the porphyrin-Fe. Since it is not evident, whether this is a general behaviour of cytochrome P-450, related to the P-450 source, or due to the cyclic nature of the substrates, it is of general interest to investigate other systems.
Recently, we have shown that the allylic hydroxylation of geraniol (1) catalyzed by microsomal cytochrome P-450,,,. from the subtropical plant Catharanthus roseus (L.) G. DON proceeds regiospecifically in favor of the Me group (E)-configurated with respect to the chain at C(6) of 1 (Scheme I ) to yield 8-hydroxygeraniol as the only product (3545%).
Scheme 1 >>