Three new vinyl acetylenes from the marine red alga laurencia

Asymmetric Total Synthesis and Structure Confirmation of (+)-(3E)-Isolaurefucin Methyl Ether

“…3 The relative configuration of (+)-(3E)-isolaurefucin methyl ether (2a) was established by extensive spectroscopic studies. The remarkable similarity of 1 H and 13 C NMR data of (+)-(3E)-isolaurefucin methyl ether (2a) with those of (+)-(3E)-chlorofucin (2b) 4 and (+)-(3E)-bromorofucin (2c) 5 was instrumental in making the structural assignment. The absolute configuration of the marine natural product was tentatively assigned based on the co-occurrence with (+)-(3E)-chlorofucin (2b) in this collection of D. plumariodes, the absolute configuration of which was previously determined by X-ray crystallography.…”

“…The absolute configuration of the marine natural product was tentatively assigned based on the co-occurrence with (+)-(3E)-chlorofucin (2b) in this collection of D. plumariodes, the absolute configuration of which was previously determined by X-ray crystallography. 4 It is of note that (+) . 3 The freeze-dried sample was reported to have been exhaustively extracted with dichloromethane and methanol.…”

Halogenated Organic Molecules of Rhodomelaceae Origin: Chemistry and Biology

“…These ACGs are all brominated, usually at C 12 , with three members, the 6,13-epoxy ACGs 526−528, having additional chlorine substitution at C 7 . 257, 299,331,332 Each of these ACGs (526−534) features an ethyl unit at one terminus, except for the 5,12-epoxy ACG derivative 535, which has a bromopropyl unit. 108 As for the other terminus, the 6,13-epoxy (526−528) and 5,12-epoxy (535) ACGs possess either a cis-or trans-enyne group, while the 4,7:6,13-bisepoxy ACGs (529−534) possess a bromoallenic moiety.…”

“…Microcladallenes A−C (519−521, Figure 42) identified from L. microcladia (off the French coast at Cape Ferrat) 329 and marilzabicycloallenes A−D (522−525, Figure 42) isolated from a newly described species L. marilzae (Canary Islands, Spain), 330 are the only representatives of the sixth and seventh subclasses of ACG derivatives to be reported so far. Each of these compounds contains a bromoallenic unit at one terminus and an ethyl-(519 and 521), or olefinic (520) Figure 43 and Supporting Information Table S13), was isolated independently by two research groups from L. obtusa with samples collected from Positano, Italy 299 and from Gokceada in the Aegean Sea. 331 So far, 10 nine-membered cyclic ether ACG derivatives including those containing 6,13-epoxy (526−528), 257,299,331,332 4,7:6,13-bisepoxy (529−534), 108,116,269,327,333−335 and 5,12-epoxy (535) 108 ring systems, were reported from the Rhodomelaceae.…”

Synthesis of (+)‐Obtusenyne

“…[7] To test the scope of this Claisen rearrangement/methylenation methodology in the synthesis of other marine-ether natural products we selected (+)-obtusenyne as our synthetic target. [8] (+)-Obtusenyne ((+)-1) was independently isolated from L. obtusa by Imre [9] and Fenical and Clardy [10] and their respective co-workers. The structure and absolute configuration of (+)-1 were assigned by a combination of spectroscopic analysis and X-ray crystallography.…”