Isolation and structure determination of the cembranoid eunicin from a new genus of octocoral, Pseudoplexaura.

The known cembranoid diterpene eunicin (1) was isolated from a new genus of octocoral, Pseudoplexaura, collected in the Caribbean. The complete assignment of the 13C and 1H NMR spectra, including differentiation of pro-R and pro-S hydrogens and elucidation of all J values, was accomplished with the aid of TOCSY, HSQC, and HMBC data, and a consideration of three low-energy conformations using SYBYL.