Total synthesis of two natural phenanthrenes: confusarin and a regioisomer

The title compounds were synthesized by radical cyclization of the corresponding stilbenes intermediates. The latter ones arose from a Wittig reaction in a stereoselective manner (Z isomer is either the only one or the major one). Confusarin (1) was prepared in 13 steps from gallic acid. Its regioisomer (2) was obtained in five steps from syringaldehyde.