Isolation and Synthesis of Novel Meroterpenoids from Rhodomyrtus tomentosa: Investigation of a Reactive Enetrione Intermediate

Abstract

Rhodomyrtusials A–C, the first examples of triketone‐sesquiterpene meroterpenoids featuring a unique 6/5/5/9/4 fused pentacyclic ring system were isolated from Rhodomyrtus tomentosa, along with several biogenetically‐related dihydropyran isomers. Two bis‐furans and one dihydropyran isomer showed acetylcholinesterase (AChE) inhibitory activity. Structures of the isolates were unambiguously established by a combination of spectroscopic data, ECD analysis, and total synthesis. Bioinspired total syntheses of six isolates were achieved in six steps utilizing a reactive enetrione intermediate generated in situ from a readily available hydroxy‐endoperoxide precursor.

Convergent biomimetic semisynthesis of disesquiterpenoid rumphellolide J

“…Although rumphellaoic acid A (5) displayed anti-inflammatory activity by inhibiting the release of elastase by human neutrophils and 4β,8β-epoxycaryophyllan-5-ol (6) enhanced the generation of superoxide anions, rumphellolide J (7) was not tested in any bioactivity assays. 2 The proposed biogenetic pathways indicate that all aforementioned isolated compounds might have originated from β-caryophyllene (1) and/or its oxide (4) as their relative configuration match with the parent compounds (Scheme 1).…”

Acylphloroglucinols with acetylcholinesterase inhibitory effects from the fruits of Eucalyptus robusta

“…(Table 4). Taking their structural characteristics and AChE inhibitory data into consideration, the observable structure-activity relationships can be summarized as follows (i) both FPMs featuring with a dihydropyran ring and acylphloroglucinol monomer were inactive; (ii) acylphloroglucinol dimers that be connected via an isopentyl moiety showed stronger AChE inhibitory effects than Rhodomyrtus tomentosa [35], the current findings indicated that FPM and acylphloroglucinol heterodimers [10] connected only by an isopentyl unit are more likely to be AChE inhibitors.…”

Polymethylated Phloroglucinol Meroterpenoids from Rhodomyrtus tomentosa and Their Antibacterial and Acetylcholinesterase Inhibitory Effects

“…These natural products have also attracted considerable interests from our research group. [7][8][9] As part of our continuing efforts to search for structurally intriguing and bioactive molecules from Myrtaceae family, three new polymethylated phloroglucinol meroterpenoids (PPMs), named rhotomentodiones CÀ E (Figure 1), were obtained from the twigs and leaves of Rhodomyrtus tomentosa. All these isolates were evaluated for their antibacterial and AChE inhibitory activities.…”