1‐Oxoniaadamantane

Abstract

Keywords: Tertiary cage oxonium ions / 1-Oxoniaadamantane / Bridgehead oxonium ions / HeteroadamantanesThe missing member of the heteroadamantane series, 1-oxoniaadamantane (4a), was prepared by the ionization of suitable bicyclic precursors under strongly acidic conditions. The ion 4a was characterized by 1 H and 13 C NMR spectroscopy. The X-ray crystal structure of ion 4a was also ob-

Synthesis, Characterization, and Reactivity of Complex Tricyclic Oxonium Ions, Proposed Intermediates in Natural Product Biosynthesis

“…26 The (Z)-halofucins were synthesized from the bromochlorides 34 and 35, and the dibromides 38 and 39 using a Stork-Zhao olefination 60 to give mixtures of the inseparable vinyl iodides 42 and 43, and 44 and 45 followed by Sonogashira cross coupling and deprotection. Figure 2c shows clearly that the resonances for C-7 (blue), C-10 (green), C-13 (purple) carbon atoms move to significantly higher chemical shift on treatment of ent-(E)-29 with a silver(I) salt, in keeping with the large 13 C NMR chemical shift changes observed on oxonium ion formation in other tricyclic systems, [62][63] whereas the resonance for C-9 (red) moves to slightly lower chemical shift. In a similar manner, Figure 2d In particular, the 1 H-13 C HMBC spectrum demonstrates the formation of trivalent oxygen.…”

“…The off-diagonal entries, which correspond to comparison between structures of different configurations, gave larger mean absolute deviations (MADs) as well as larger deviations of individual 13 C and/or 1 H NMR chemical shifts. Furthermore, the chemical shifts of the carbon and proton atoms adjacent to the trivalent oxygen were in keeping with simpler tricyclic oxonium ions. , …”

“…Furthermore, the chemical shifts of the carbon and proton atoms adjacent to the trivalent oxygen were in keeping with simpler tricyclic oxonium ions. [62][63]…”

Gebändigt: das hoch reaktive Oxoniumion

“…4 Über neue Oxoniumionen wird recht regelmäßig berichtet, allerdings sind Halbkäfigverbindungen wie 1 – 3 und Käfigverbindungen, z. B. das kürzlich von Olah et al 5. beschriebene Oxaadamantan 4 , relativ selten.…”

Taming the Highly Reactive Oxonium Ion

“…Imagine then, my surprise and that of my students upon reading the recent communication by Mascal and co-workers disclosing the preparation of "extraordinary" oxonium ions (Figure 1), namely tricyclic oxatriquinane 1, oxatriquinene 2, and oxatriquinacene 3. [3,4] New oxonium ions are reported on a somewhat regular basis, though admittedly half-cage compounds such as 1-3, as well as cage compounds like oxaadamantane 4 recently reported by Olah et al, [5] are quite rare. In fact, the only previously well-characterized bicyclic or tricyclic oxonium ion is 5, described by Klages and Jung in 1965.…”