Discovery of a novel one-step RuO4-catalysed tandem oxidative polycyclization/double spiroketalization process. Access to a new type of polyether bis-spiroketal compound displaying antitumour activity

Four novel C₃₀ polyether bis-spiroketals, displaying selective inhibition of the BT474 breast-derived cancer cell line, have been obtained from squalene through an unprecedented one-step, RuO₄-catalysed, cascade process characterised by a tandem oxidative pentacyclization/double oxidative spiroketalization sequence. Preliminary studies indicate that the Ru-mediated spiroketalization steps proceed with retention of configuration at the forming spirocentres. A similarity with the oxidative behaviour of PCC has been disclosed.