Exploration of the Paternò–Büchi Reaction as a Potential Route to the Oxetan Ring of Taxol®

Abstract

Two photochemical pathways to paclitaxel-like oxetan rings have been examined. In the first approach, an intramolecular Paternò–BÜchi reaction on a 6,7-enal was attempted without success. The intermolecular variation using a bicyclic alkene in the presence of either benzaldehyde or acetophenone delivered oxetans whose regiochemistry was the same as that found in paclitaxel but opposite in stereochemistry. The crystal structures of a key intermediate diol and a photochemically generated oxetan are reported.