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High-resolution ion-mobility measurements have resolved a number of isomers for carbon cluster anions in the drift-time region previously assigned to monocyclic rings. Tight-binding calculations have been performed to generate feasible geometries, which were compared to the experimental data by calculating their mobilities. Structures composed of a short chain of carbon atoms attached to a carbon ring are found to be the most plausible geometries for these new isomers. A number of different bicyclic ring isomers have also been resolved for the first time. [S0031-9007 (98)06131-6] PACS numbers: 61.46. + w, 36.40.Wa

All things converge: A highly convergent synthesis of (−)‐okilactomycin utilizes a Prins‐type Maitland–Japp cyclization for the fragment assembly of two complex intermediates (see scheme). The synthesis also employs a highly diastereoselective Lewis acid promoted Diels–Alder reaction and an olefin ring‐closing metathesis to close a strained 11‐membered macrocycle.

We have developed a route for the stereoselective synthesis of 1-oxa-2,2-(dimesityl)silacyclopentane acetals, intermediates in the synthesis of highly functionalized 1,3-diols. This route involves a diastereoselective conjugate addition reaction of a hydrosilyl anion, a subsequent diastereoselective enolate alkylation, and a fluoride-catalyzed intramolecular hydrosilylation reaction to afford the oxasilacyclopentane acetal. A highly selective nucleophilic substitution reaction, followed by oxidation of the C-Si bond, leads to the desired polyol.

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