Briarane diterpenoids are characterized by a bicycle [8.4.0] ring system fused by a γ-lactone group, with high oxidization and esterication by all kinds of acyls, that is, acetyl, isovalerate, etc. These compounds exhibit a variety of biological activities such as cytotoxicity, anti-inammatory activity, antivirus activity, insecticidal activity, immunomodulation, and antifouling activity. Because of their unique structures and interesting biological activities, signicant efforts have gone into the discovery of new briarane diterpenoids. These efforts have culminated in the discovery of more than 600 briarane family members (Sung et al. 2005, 2011; Sung, Sheu, and Xu 2002; Sung, Sheu, et al. 2008) since the rst briarane-type diterpenoid, briarane A, was isolated from the West Indian gorgonian Briareum asbestinum by Burks et al. in 1977 (Burks et al. 1977). Most of these briaranes possess a chlorine atom, an epoxy group, and a double bond as substituents.