Xanthochrysanthones A−C, Novel Lobster‐Shape Cinnamoyltriketone Dimers with Antiviral Activities from Xanthostemon chrysanthus

Abstract Three pairs of enantiomeric cinnamoyltriketone dimers, (+)‐ and (−)‐xanthochrysanthones A−C [(+)‐ and (−)‐ 1 – 3 )], were recognized and obtained from Xanthostemon chrysanthus by employing the building blocks‐based molecular network (BBMN) strategy. Compounds 1 – 3 featured two new types of lobster‐shape carbon skeletons with unprecedented spiro[cyclohexane‐1,2′‐xanthene] or benzo[7,8]oxocino[4,5‐ b ]chromene tetracyclic ring systems. Their structures with absolute configurations were established by comprehensive spectroscopic analyses, X‐ray crystallography, and ECD calculations. Compounds 1 – 3 represent the first example of phloroglucinol derivatives that are biogenetically constructed by a De Mayo reaction followed by Michael addition. Additionally, compounds 1 – 3 exhibited significant antiviral activity against respiratory syncytial virus (RSV). Time‐of‐addition assays indicated that compound 3 specifically acts on the early stages of the virus replication process in RSV.