2:1-Cocyclization of but-2-yne with the ?-allyl ligand in cationic ?-allyl complexes of ruthenium, osmium, and rhodium

Demethylation of Coordinated Hexamethylbenzene. Carbon−Carbon Bond Activation during Ruthenium-Mediated [3 + 2] Allyl Alkyne Cycloaddition Reactions

“…Metal-mediated “oxidative” allyl/alkyne [3 + 2] cycloaddition reactions have been previously reported for half-sandwich η 5 -cyclopentadienyl, η 5 -pentamethylcyclopentadienyl, , and η 6 -arene 8 complexes of the late transition metals (Figure ). The reaction represents an unexploited convergent synthesis of differentially substituted cyclopentadienyl ligands within the coordination sphere of a metal and is potentially attractive for the development of catalyst libraries and derivatizing alkyne-rich materials and polymers.…”

Oxodienyl/Alkyne Coupling Reactions in Half-Open Ruthenocenes(II) and Related Species of Ru(IV)

“…There is widespread interest in organoruthenium reactions with alkynes, especially terminal and internal alkynes, which involve hydrogen, alkyl, aryl, or alkoxy-carbonyl substituents, because such systems could induce insertion reactions in a variety of chloro- or hydrido-ruthenium(II) − and -(IV) 4 complexes. Convenient precursors of substituted cyclopentadienones from reactions of compounds with labile coordinated ligands [Cp‘Ru(CO)(MeCN) 2 ] [Cp‘ = Cp, Cp*] with various alkynes and a variety of examples of the ruthenium-alkyne chemistry have been reported.…”

Cobalt-Mediated Intermolecular Allyl/Alkyne [3 + 2 + 2] Cycloaddition Reactions. A Practical Metal Template for Convergent Synthesis of Functionalized Seven-Membered Rings

“…η 3 -Allyl alkyne coupling reactions proceed via vinyl olefin intermediates and typically provide open-chain η 5 -pentadienyl complexes (path a) or η 5 -cyclopentadienyl complexes (path b) from reaction with a single alkyne (Scheme ). Incorporation of two alkynes has also been reported, leading to the formation of η 1 ,η 4 -methanocyclohexadiene complexes (path c) . By controlling the regiochemistry of the migratory insertion that determines ring size in the double alkyne reactions, we recently established the first allyl/alkyne cycloaddition reactions to yield seven-membered-ring systems with high selectivity (path d). , To exploit the synthetic potential of that iridium-mediated reactivity pattern, less expensive and more reactive organometallic systems were sought for the development of organic methodology.…”