5,6-, and 6,6-mono-benzannulated spiroketals using a novel cross-metathesis-radical-cyclisation approach is reported. Cross metathesis between two olefin coupling partners resulted in the formation of a heterodimer which upon hydrogenation furnished a saturated alcohol product. Oxidative radical cyclisation then afforded the desired monobenz-annulated spiroketals in good overall yield.
The synthesis of both mono and bisbenzannulated spiroketals using an oxidative radical cyclization approach is investigated. Although unsuccessful in uncovering a novel route toward bisbenzannulated spiroketals, the oxidative radical cyclization does facilitate a new approach to monobenzannulated spiroketals such as those found in berkelic acid and in the chaetoquadrins.