Some Constituents of Lycopodium Inundatum L

Abstract

Three new alkaloids-inundatiiie [V], isoinundatine [VI] and dehydrolycopecurine [VIII- Of the five alkaloids isolated, lycopodine and lycodoline were identified by direct comparison with authentic samples. The three remaining alkaloids have not been reported previously and their structures are assigned below.The molecular weight of inundatine** [V](M+ = 261) is consistent with the formula C,,H,,NO,.The N M R spectrum reveals the presence of a secondary C-methyl group (doublet at 0.93 ppni) and of a labile proton (broad signal at 2.02 ppm which disappears after D,O equilibration). The absence of signals above 4.5 ppm suggests that inundatine does not contain olefinic protons.The appearance in the mass spectrum ( fig. I ) of a peak a t M-17 and the formation of 0-acetylinundatine [XIII] (M' = 303) on acetylation establishes that the labile proton belongs to a hydroxyl group.The fact that the IR(KBr) of inundatine shows a carbonyl stretching vibration at 1695cm-' and that its mass spectrum displays an intense fragmentation peak at mje = M f -28 is consistent with the presence of a ketone group. This is further proved by the formation of a dihydro compound ( M + = 263) on reduction with sodium borohydride. Acetylation of dihydroinundatine gives rise to a diacetyl derivative ( M + = 347).

A Unified Strategy for the Synthesis of 7-Membered-Ring-Containing Lycopodium Alkaloids

“…Additionally, himeradine A ( 1 ) contains in total 7 rings, 10 stereo­centers, 3 potentially basic nitrogens, and a quinolizidine subunit appended to the core via a methylene linker, rendering 1 arguably the most synthetically challenging Lyco­podium alkaloid. Lyco­pecurine ( 3 ) and related alkaloids also contain a strained C4–C10 bond and an analogous core structure to 1 and 2 but differ in that the A ring is rearranged, which is characteristic of members of the lyco­podine class. Lyco­nadins A ( 5 ) and B ( 6 ) are members of the miscellaneous class and possess a unique pentacyclic ring system.…”