Structures of two bacteriohopanoids with acyclic pentol side-chains from the cyanobacterium Nostoc PCC 6720

Two bacteriohopanepentols 2 and 3 have been isolated from the cyanobacterium Nostoc PCC 6720. Their structures were elucidated by 1H, 13C-NMR and mass spectrometry. The absolute configurations of the acyclic 1,2- and 1,2-/1,3-mixed pentol side-chains were determined by bichromophoric exciton coupled dichroism on microgram scale. An improved first step anthroylation in the two-step derivatization is also described.