Osmium(II)-Induced Rearrangement of Allenols for Metallafuran Complexes

作者：Shek, Hau -Lam; Tam, King -Ting; Yiu, Shek-Man; Tse, Man-Kit; Morris, Robert H.; Wong, Chun-Yuen^*

来源：Organometallics, 2022, 41(15): 1931-1941.

DOI：10.1021/acs.organomet.2c00113

• METAL-CATALYZED REACTIONS
• INSERTION REACTIONS
• BOND ACTIVATION
• CHEMISTRY
• OSMIUM
• CYCLIZATION
• VINYLIDENE
• OSMACYCLES
• REACTIVITY
• ALKYNES

Osmafuran complexes in the form of cis-[Os(L boolean AND L)(2)(C boolean AND O)](+) (L boolean AND L = 1,1-bis(diphenylphosphino)methane (dppm) or 2,2'-bipyridine (bpy); C boolean AND O = [C(CH3)C(CH3)CRO](-), coordinating atoms in italics) were prepared from reactions between dichloro-Os(II) complexes cis-[Os(L boolean AND L)(2)Cl-2] and allenols H2C=C=C(CH3)(CH(R)(OH)) in alcoholic solvents. Rearrangement of allenolates H2C=C=C(CH3)(CH(R)(O-)) involving deprotonation of the secondary alcoholic carbon and protonation of the terminal allenic carbon was evident from the X-ray crystal structures of the resulting complexes. Density functional theory (DFT) calculations suggested a rearrangement mechanism involving Os-alkene intermediates cis-[Os(L boolean AND L)(2)(H2C=CH-C(CH3)(=C(R)(O-)))]+ but not Os-hydride intermediates. Overall, these osmafurans are not directly derived from common metal-allene reaction patterns.

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