Biosynthesis of the C15-acetogenin laurepoxide may involve bromine-induced skeletal rearrangement of a Δ4-oxocene precursor

Abstract

An electrophilic bromine catalyzed skeletal rearrangement of an Δ4-oxocene to an epoxy furan has been described. This skeletal rearrangement suggests a plausible mechanism for the biosynthesis of the C15-acetogenin laurepoxide.

Computationally guided discovery of a reactive, hydrophilic trans-5-oxocene dienophile for bioorthogonal labeling

“…41,42 Here we report the computational design and synthesis of a trans -5-oxocene (“oxoTCO”, 3 ) – a small, hydrophilic, and highly reactive dienophile for use in the bioorthogonal tetrazine ligation reaction. The reaction of 3 (2.2 : 1 d.r.)…”

“…In the course of our synthetic studies on transannulations of cis - and trans -5-oxocenes, we queried whether such com-pounds would engage in rapid bioconjugation reactions 41,42. Here we report the computational design and synthesis of a trans -5-oxocene (“oxoTCO”, 3 ) – a small, hydrophilic, and highly reactive dienophile for use in the bioorthogonal tetrazine ligation reaction.…”

Dual-Reactivity trans-Cyclooctenol Probes for Sulfenylation in Live Cells Enable Temporal Control via Bioorthogonal Quenching

“…32,33 We reasoned that the olefinic strain of transcyclooctene 1 would make it particularly adept to form a thiiranium ion (2), and that the ring system would position a hydroxyl nucleophile for subsequent transannular attack (Fig 1). 32,34 We show that these sulfenic acid modifying trans-cycloocten-5-ol (SAM-TCO) probes function for the rapid, selective, and stable capture of sulfenic acids in live cells. Unique to this approach, bioorthogonal tetrazine ligation can quench SAM-TCO reagents in live cells with temporal control, thereby minimizing concerns about redox changes resulting from cell lysis.…”

Forwards and backwards – synthesis of Laurencia natural products using a biomimetic and retrobiomimetic strategy incorporating structural reassignment of laurefurenynes C–F

“…[20][21][22] Key to correcting many of these structural misassignments have been postulates regarding the biosyntheses of acetogenic Laurencia natural products, many of which have been proposed to proceed through complex oxonium ion intermediates. 15,[23][24][25][26][27][28][29][30][31][32][33] These biogenetic postulates have allowed rational prediction of the likely structures of a number of the natural products 15,21,22,26,34 and in a number of cases the biogenetic arguments have been augmented by DFT calculations of both proton and carbon NMR chemical shis 14,22,34 for a range of candidate structures with ultimately the structure of the natural products being established through total synthesis. 35 Among the acetogenic Laurencia natural products whose structures have been reassigned are laurefucin, 36,37 obtusallenes V, VI and VII, 16,19,26 elatenyne, [12][13][14][15]38 laurendecumenyne B, 15,39,40 aplysiallene, 41,42 a chloroenyne from Laurencia majuscula 13,34,38,43 and laur...…”