Oxidative generation of isobenzofurans from phthalans: application to the formal synthesis of (±)-morphine.

ABSTRACT: Treatment of phthalan derivatives with p-chloranil in dodecane in the presence of molecular sieves at 160-200 °C allowed the generation of unstabilized isobenzofurans, which underwent intramolecular Diels-Alder reaction to give endo cycloadducts exclusively. The cycloaddition turned out to be reversible, providing an equilibrium mixture of endo adducts when heating a substrate with a stereocenter on the tether. We also demonstrated the regioselective allylation of an oxygen-bridged cycloadduct upon exposure to EtAlCl₂ in the presence of allyltrimethylsilane, and the conversion to Rice's intermediate completed a formal synthesis of (±)-morphine.

SUBMITTER: Kage M 

PROVIDER: S-EPMC11523798 | biostudies-literature | 2024 Oct

REPOSITORIES: biostudies-literature