Two New Halogenated Briarane Diterpenes from the Papuan Gorgonian Coral <i>Junceella fragilis</i>

Abstract

Abstract Two new halogenated briarane diterpenes, (−)-2-deacetyljunceellin (1) and (−)-3-deacetyljunceellin (2), and five known diterpenoids, junceellin, praelolide, junceellolide A, B, and D were isolated from the Papuan gorgonian coral Junceella fragilis. The structures of the new metabolites were determined by extensive 2D NMR experiments and by chemical conversion. The absolute configuration of 2 was determined through the 1H NMR study of the corresponding ester with a newly developed chiral auxiliary 3a.