Synthesis and isolation of highly reactive .eta.3-allyl alkyne complexes of iridium via the inner-sphere .eta.3-allyl triflate complex (C5Me5)Ir(.eta.3-C3H5)OTf. Facile conversion to alkyne metallacyclobutane complexes by nucleophilic addition

Labile Hydrido Complexes of Iridium(III): Synthesis, Dynamic Behavior in Solution, and Reactivity toward Alkenes

“…On warming to room temperature, compound 18 eliminates propane; however, the expected iridium(I) species resulting from this abstraction cannot be observed. Instead, a mixture of allylic C−H activation 3a,5a, products is formed, namely, the allylhydrido derivatives [IrH(η 3 -C 3 H 5 )(P i Pr 3 )(NCCH 3 ) 2 ]BF 4 ( 19 ) and [IrH(η 3 -C 3 H 5 )(η 2 -C 3 H 6 )(P i Pr 3 )(NCCH 3 )]BF 4 ( 20 ), respectively. Both complexes 19 and 20 have been isolated and fully characterized by analytic and spectroscopic methods.…”

“…The organometallic chemistry of iridium(III) is dominated by compounds containing six-electron donor ligands such as cyclopentadienyl, indenyl, trispyrazolyl, or triphosphines and by complexes coordinating various monodentate phosphine ligands, generally two or more − However, despite this remarkable ability of substrate activation, the subsequent conversion of the activated substrates into functionalized organic products has been achieved in just a few cases, and the incorporation of such activation steps into catalytic cycles remains to be solved . This problem has been extensively discussed 2,4 and attributed to the inability of the products obtained in the activation step to generate new coordination vacancies, thus preventing further reaction with other substrates.…”

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.…”

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

“…The unsubstituted allyl triflate complex 2a is prepared in high yield by treatment of allyl alcohol with (C 5 Me 5 )Co(ethylene) 2 ( 1 ) and triflic acid. The red-brown inner-sphere triflate complex 2a thus formed can be used in situ or isolated in 85−90% yield. , Substituted η 3 -allyl derivatives are best prepared from the 1,3-diene by thermal exchange followed by protonation, without isolation of the intermediate diene complex (eq 1). Thus, η 3 -crotyl and η 3 -1,2-dimethylallyl triflate complexes 2b and 2c − are formed in near-quantitative yield and can be isolated in crystalline form in yields in excess of 80%.…”