Structures and absolute stereochemistry of five new secospatanes and a spatane isolated from the brown alga Dilophus okamurai Dawson

Abstract

Five new secospatane diterpenoids, secospatacetal A, B, C, D, and E have been isolated from the brown alga Dilophus okamurai DAWSON, and their structures as well as absolute configurations have been elucidated by means of NMR spectroscopy and chemical transformations. Also, the structure of a known spatane diterpene has been revised.