First synthesis and absolute configuration of phorbasin H, a diterpene carboxylic acid isolated from the sponge Phorbas gukulensis.

The first synthesis of phorbasin H, a diterpene carboxylic acid isolated from the sponge Phorbas gukulensis, was achieved using 1,4-trans-cyclohexanedimethanol and (S)-citronellal as starting materials. The data collected in this synthesis indicated the absolute configuration of the naturally occurring phorbasin H to be S.