The Discreet Structural Diversity of Briarellins: DU8+ Guided Multiple Structure Revisions Yielded Two Unknown Structural Types

Briarellins, a subset of C2–C11 cyclized cembranoids, were proposed to contain a C3–C14 ether or lactone bridge, similar to asbestinins. However, the total synthesis of the proposed structure of briarellin J revealed a misassignment. We revisited briarellins, computationally, with the help of a recently developed hybrid DFT/parametric method, DU8+, and revised the structures of briarellin C14–C3 ε-lactones to new structural types containing either a C14–C11 or C14–C12 lactone bridge. The original structures of briarellin and asbestinin ethers were confirmed.