Synthesis and thermal racemization of the 3,4-oxide metabolite of benzo[c] phenanthrene

Abstract

Both the racemic form and the (–)-(3R,4S)-enantiomer of benzo[c] phenanthrene 3,4-oxide have been synthesized in 12 steps from naphthalene. The absolute stereochemistry of the arene oxide enantiomers and related chiral derivatives has been determined by n.m.r. methods. Spontaneous thermal racemization of (–)-benzo[c]phenanthrene 3,4-oxide occurred with a barrier to racemization (ΔG^≠_{29 °C} 24.6 kcal mol^–1)(1 kcal = 4.184 kJ) in accord with predictions based upon PMO calculations.