Synthetic Approach toward Diverse Oxa-Cages via Olefin Metathesis

This article demonstrates a late-stage modification of the cage propellanes that are transformed into intricate oxa-cycles via ring-rearrangement metathesis (RRM) and regioselective ring-closing metathesis (RCM) as crucial steps. In addition, we also report the extended pentacycloundecane (PCUD)-based oxa-cages involving the domino cycloetherification followed by olefin metathesis. These oxa-cages involve a domino sequence in which the PCUD core unit remains intact. [Ru]-based Grubbs catalysts are used to execute the metathesis step to assemble these higher-order oxa-cage systems. Spectroscopic data assigned structures of various products and were further supported by single-crystal X-ray diffraction analysis. The synthetic approach to these cage polycycles involves high complexity generating processes such as Diels-Alder reaction, [2 + 2] photocycloaddition, and RRM as well as RCM.