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A remarkable bioinspired EDDA-mediated method for the selective construction of biologically interesting and highly strained bridged methanodibenzo[b,f][1,5]dioxocin flavonoid scaffold was uncovered by starting from a variety of readily available acylphloroglucinol and 2-hydroxycinnamaldehyde substrates. This method merges a fascinating olefin isomerization/hemiacetallization/dehydration/[3 + 3]-type cycloaddition cascade reaction driven by an in situ generated chromenylium intermediate and provides a convenient and viable synthetic strategy for the efficient access of such flavonoid analogues.

Cytorhizins A–D, four novel polyketide heterodimers, were isolated from the endophytic fungus Cytospora rhizophorae A761. These new compounds shared an unprecedented 6/6/5/6/8 or 6/6/5/6/7 pentacyclic ring system and fused as a fascinating cagelike skeleton, embodying by a polyoxygenated isopentyl unit and a highly structure-combined benzophenone scaffold. Their structures were elucidated by extensive spectroscopic analyses and X-ray diffraction techniques. Moreover, compounds 1–4 were evaluated for in vitro cytotoxicity and antimicrobial activity.