Palhicerines A-F, Lycopodium alkaloids from the club moss Palhinhaea cernua.

Four fawcettimine-type (palhicerines A-D, resp.) and two lycopodine-type (palhicerines E and F) Lycopodium alkaloids together with twenty known ones were isolated from the whole plant of Palhinhaea cernua. The structures and absolute configurations of the palhicerines A-F were determined by extensive spectroscopic methods, single-crystal X-ray diffraction analyses, chemical transformation, and electronic circular dichroism (ECD) calculations or induced electronic circular dichroism (IECD) spectra. Among the isolates, the new C/D-ring of the palhicerines A-C (trans-fused fawcettimine-type alkaloids) are rare, and each possesses a β-oriented C-16 methyl group and a distinctive tertiary methoxy group at C-13. Chemotaxonomy for differentiating species in the genus Palhinhaea is briefly discussed.