Classification of Diverse Novel Phloroglucinols

Phloroglucinol derivatives are a major class of secondary metabolites with fascinating chemical structures and intriguing biological activities. A large number of differently substituted and structurally diverse phloroglucinol derivatives have been isolated from the land plants, meanwhile, a few phloroglucinols with unique skeletons are also reported. The polycyclic polyprenylated acylphloroglucinols (PPAPs) feature a highly oxygenated and densely substituted bicyclo[3.3.1]nonane-2,4,9-trione or bicyclo[3.2.1]octane-2,4,8-trione core decorated with C5H9 or C10H17 (prenyl, geranyl, etc.) side chains (the latter in several isomeric forms). The variability of phloroglucinols usually resulted in the construction of highly functionalized polycyclic scaffolds with complex structures.