Synthetic explorations of the briarane jungle: progress in developing a synthetic route to a common family of diterpenoid natural products

Abstract

The briarane diterpenoids are a large family of marine natural products that have been primarily isolated from gorgonian octocorals around the world. Structurally, the family is characterized by a trans-fused bicyclo[8.4.0]tetradecane ring system containing a central, stereogenic, all-carbon quaternary carbon (C1) flanked by three additional stereocentres (C2, C10, C14). Many family members have demonstrated biological activity in numerous areas, including: cytotoxicity, anti-inflammatory, antiviral, antifungal, immunomodulatory and insect control. Despite their interesting structural properties and bioactivity, the briaranes have been largely overlooked by the synthetic community. However, in recent years, several research groups have reported progress toward developing a synthetic route to these natural products. Most of these efforts have focused on the stereoselective construction of the central C1–C2–C10–C14 stereotetrad. This review will discuss the various synthetic efforts aimed at the briarane diterpenoids along with the challenges that remain.

Marine Natural Products: The Important Resource of Biological Insecticide

“…Analysis of Bornean soft coral from Borneo Island by Takahiro gave a new norditerpene, chabrolene ( 35 ), which could also be the repellent agent towards maize weevil Sitophilus zeamais [82] . The briarane diterpenoids from gorgonian octocorals is a special category marine nature products with variety of bioactivity including insecticidal activity and led to extensive research [83] . Saksit et al .…”

Metabolic Profiling of the Soft Coral Erythropodium caribaeorum (Alcyonacea: Anthothelidae) from the Colombian Caribbean Reveals Different Chemotypes

“…Briarane-type diterpenoids represent one of the most common natural product families to be isolated from gorgonian octocorals, with over 700 briarane diterpenoids characterized [28]. The biosynthetic origin of this skeleton was proposed as the result of cyclization between C3 and C8 of a cembrane skeleton, another widely distributed diterpene scaffold in marine gorgonian species, followed by further oxidative processing [29]. These oxidative processes are the responsible of the high diversity of briarane diterpenoids, due to the expression of several CYP450 enzyme-isoforms [30].…”

Marine diterpenoid targets STING palmitoylation in mammalian cells

“…Yet for many briarane-type diterpenoids, in-depth studies of their biological activities are severely hampered by the lack of material and challenging chemical syntheses. No total synthesis of a briarane-type diterpenoid has been completed to date 16 – 18 . In addition, no direct cellular target of this class of natural products has been reported.…”