Fig. 2.
Proposed mechanism for cytochrome P450-mediated conversion of taxa-4(5),11(12)-diene and taxa-4(20),11(12)-diene to taxa-4(20),11(12)-dien-5α-ol involving hydrogen abstraction at C5 or C20 to provide the common allylic radical, followed by oxygen insertion at the C5α-face. Taxa-4(5),11(12)-diene and taxa-4(20),11(12)-diene isomerization was not observed (Jennewein et al. 2004)