Synthesis of (2R,8′S,3′E)-δ-tocodienol, a tocoflexol family member designed to have a superior pharmacokinetic profile compared to δ-tocotrienol

A group of side chain partially saturated tocotrienol analogues, namely tocoflexols, have been previously designed in an effort to improve the pharmacokinetic properties of tocotrienols. (2R,8′S,3′E)-δ-Tocodienol (1) was predicted to be a high value tocoflexol for further pharmacological evaluation. We now report here an efficient eight-step synthetic route to compound 1 utilizing naturally-occurring δ-tocotrienol as a starting material (24% total yield). The key step in the synthesis is oxidative olefin cleavage of δ-tocotrienol to afford the chroman core of 1 with retention of chirality at the C-2 stereocenter.