Enantioselective Synthesis of Organosulfur Compounds via [2,3] Rearrangements of Ylides Derived from Di(allyl) and Di(propargyl) Sulfide Complexes. Control of Carbon Configuration by an Easily Resolved and Recycled Chiral Transition Metal Auxiliary

Cagle, Phillip C.; Meyer, Oliver; Weickhardt, Konrad; Arif, Atta M.; Gladysz, J. A.

doi:10.1021/ja00152a014

Abstract The bonding in beryllocene, [BeCp₂], took decades to establish, owing to its unexpected mixed hapticity structure (i.e., [Be(η⁵‐Cp)(η¹‐Cp)]). Beryllium complexes containing the indenyl ligand, which is a close relative of the cyclopentadienyl anion, but which is also known to exhibit its own bonding peculiarities (e.g., facile η⁵⇄ η³shifts), have remained unknown. Standard metathetical approaches to their synthesis (e.g., with K[Ind′] + BeX₂in an ether solvent) give rise to intractable oils from which nothing identifiable can be isolated. In contrast, mechanochemical preparation, involving the solvent‐free grinding of BeBr₂and potassium indenides, leads to the production of discrete (indenyl)beryllium complexes, including [Be(C₉H₇)₂] (1) and [Be{1,3‐(SiMe₃)₂C₉H₅}Br] (2). The former displays η⁵/η¹‐coordinated ligands in the solid state, but DFT calculations indicate that an η⁵/η⁵‐conformation is less than 5 kcal mol⁻¹higher in energy.

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