Benzannulated spiroketal natural products: isolation, biological activity, biosynthesis, and total synthesis

The spiroketal moiety is an important privileged scaffold that occurs extensively in natural products, drugs, and bioactive molecules. Naturally occurring spiroketals are numerous, however aryl-fused spiroketals are relatively rare. The only comprehensive review disclosing the isolation, biological activity, and synthesis of benzannulated spiroketal natural products was published nearly a decade ago. This review will serve as an update of the 2009 review and include all known families of benzannulated spiroketals, detailing their isolation and biological activity where relevant. Although not exhaustive, endeavours towards their total synthesis will be discussed.