Cobalt-Mediated Two-Carbon Ring Expansion of Five-Membered Rings. Electrophilic Carbon−Carbon Bond Activation in the Synthesis of Seven-Membered Rings
作者:Trevor L. Dzwiniel、Jeffrey M. Stryker
DOI:10.1021/ja047852+
日期:2004.8.1
Electrophilic cobalt(III) mediates an unprecedented two-carbon ringexpansion of coordinated five-membered rings, leading to a remarkably general new strategy for the synthesis of seven-membered carbocycles from readily available five-membered ring substrates. The reaction, a metal-mediated [5 + 2] cyclopentenyl/alkyne cycloaddition, proceeds via initial protonation of a cobalt(I) cyclopentadiene complex
endo-hydride abstraction from exo-substituted cyclopentadienecyclopentadienylcobalt; synthesis of monosubstituted cobalticinium salts
作者:N. El Murr
DOI:10.1016/s0022-328x(00)89185-8
日期:1981.3
phenyl-cyclopentadienecyclopentadienylcobalt is very easily obtained when a cobalticinium cation reacts with methyl- or phenyl-lithium. Triphenylmethyl tetrafluoroborate abstracts the endo-hydrogen atom from these two complexes, and this enabled us to prepare the corresponding mono-substituted cobalticinium salts.