Viral infections pose a significant economic burden and societal threat worldwide. The recent COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-Co V -2 ) has starkly highlighted the risks posed by respiratory viruses to vulnerable populations and the urgent need for effective antivirals. Respiratory Syncytial Virus (RSV) is also a poten t respiratory pathogen and is responsible for high levels of acut e lower respiratory tract infections in infants, the elderly an d immunocompromi sed adults. Despite the urgency, the current landscape of antiviral treatments is sparse , underscoring the critical need for further antiviral development. Natural products have a long and successfu l history as privileged starting points in the search for novel therapeutic approaches to counter infectious diseases. On e effective strategy for navigating their vast chemical space is to deconvolute molecular compositions of herbal remedie s described in traditional Chinese medicine (TCM), thus buildin g upon a wealth of knowledge based on centuries of use. For example, the genus Cleistocalyx, belonging to the Myrtac e ae family, comprises various plant species, some of which are use d in Southeast Asia to create medicinal teas. Cleistocal yx operculatus (Roxb.) Merr. and Perry, a tree native to southe r n China, has been traditionally used to treat cold, fever, an d inflammation with extracts from its buds and leaves. Cleistocaltone A (1, Figure ), a polymethylated phloroglucin o l meroterpenoid (PPM) isolated from the buds of C. operculat u s by Ye, Wang, and co-workers in 2019, was demonstrated to possess promising in vitro activity against RSV. In nature, components from diverse classes of natural produc t s frequently merge to form compounds with novel biological activities. Among these classes, phloroglucinol meroterpeno i d s stand out. These compounds consist of a phloroglucin o l segment and a terpene segment. The terpene portion typicall y originates from a geranyl group, which undergoes a series of biosynthetic transformation s involving oxidation an d cyclization. For instance, elodeoidol G (2, Figure ), an antiinflammatory agent isolated by Luo, Kong, and coworke r s, features a terpene moiety proposed to be biosynthesized fro m an oxidized geranyl building block through a series of epoxidations and an acid-catalyzed epoxide opening cascade . Similarly, the cytotoxic compound hyphenrone J (3, Figure ), isolated by Qin, Xu, and coworkers, contains two prenyl grou p s and an oxidized geranyl side chain. Biosynthetically, the phloroglucinol portion of cleistocaltone A (1) is proposed to originate from champanone B (4, Figure ). Addition of geranyl pyrophosphate (GPP, 5) then forms geran yl champanone B 6. Subsequent desaturation of the geran yl terminus and isomerization of the homobenzylic doubl e bon d generates a triene, enabling an intramolecular Diels-Ald e r cycloaddition (IMDA) with the cinnamoyl dienophile.