The Structure of Palominol by Interpretation of Two-Dimensional nmr Shift Correlation Experiments: Isolation and Structure Determination of Isopalominol

Abstract

The dolabellane diterpenoid palominol [1] was reisolated from the Caribbean gorgonian Eunicea laciniata and subjected to a total structural assignment through the application of several 2D nmr techniques that included COSY, ROESY, INADEQUATE, HMQC, and proton-detected long-range heteronuclear chemical shift correlation (HMBC). The revised structure of palominol proposed by Shin and Fenical was rigorously confirmed by these methods. The unequivocal assignments of the 1H- and 13C-nmr spectra of palominol are reported. A new diterpenoid, isopalominol [5], also of the dolabellane class, has been isolated from the same specimen of Eu. laciniata and its structure defined by combined spectral and chemical methods.