Photochemische addition konjugierter diene an tricarbonyl-η-1,3,5-cycloheptatrien-chrom(0)

Metal-Assisted Cycloaddition Reactions in Organotransition Metal Chemistry

“…In a series of papers, Kreiter et al [729][730][731][732][733][734][735] or if the reaction is run in a donor solvent (THF). 734 The authors indicate 731 that the reaction cannot be extended to other η 6 -cyclopolyene complexes such as (η 6 -1,3,5-cyclooctatriene)Cr(CO) 3 or (η 6 -1,3,5,7-cyclooctatetraene)Cr(CO) 3 and that the molybdenum and tungsten homologues of 448 do not give comparable reactions.…”

“…In a series of papers, Kreiter et al. − have reported on the photochemically induced [6+4] cycloaddition of conjugated dienes 461 to (η 6 -cycloheptatriene)- ( 448 ), (η 6 -heptafulvene)- and (η 6 -heptafulvalene)tricarbonylchromium moieties. [An overview is given in ref .]…”

Metal-Mediated Cycloaddition Reactions of the η5-Cyclohexadienyl Ligand. Synthesis and Reactions of [5 + 2] Single and [5 + 2],homo[5 + 2] Double Cyclohexadienyl−Alkyne Adducts of Manganese

“…Transition metal-mediated cycloaddition reactions continue to attract interest because they allow the efficient and stereoselective synthesis of a variety of ring systems . In particular, medium-size carbo- and heterocyclic rings can be accessed via transition metal-mediated higher-order cycloadditions, , and Rigby and co-workers have shown that the [6 + 2] and [6 + 4] processes, originally discovered in the 1970s, , can be extended to a range of trienophiles − as well as to the syntheses of natural products. , We 16,17 and others 18 have reported the [6 + 2] addition of alkynes to the [(η 6 -triene)Cr(CO) 3 ] manifold (Scheme ), and more recently we and Kreiter and co-workers have extended this protocol to η 5 -dienyl ligands using tricarbonyl(η 5 -cyclohexadienyl)manganese(I). In these latter studies, sequential [5 + 2], homo [5 + 2] double alkyne additions to the dienyl ligand gave tricyclo[5.2.1.0 4,9 ]deca-2,5-dien-10-yl derivatives, further studies on which are described herein.…”

Chromium(0)-Promoted Multicomponent Cycloaddition of Tethered Diynes with Cyclic Trienes: Application to the Total Synthesis of 9-epi-Pentalenic Acid

“…Chromium(0)-promoted higher order cycloadditions, such as [6π+2π] and [6π+4π] combinations, have also received considerable attention in recent years due to their stereocomplementarity and periselectivity advantages over the corresponding metal-free cycloaddition processes . An intriguing and potentially significant extension of this chromium(0)-mediated ring assembly has been realized with the recent discovery of a novel and efficient three-component, one-pot cycloaddition process, characterized by the Cr(0)-mediated combination of 2 equiv of an alkyne with a cyclic triene 4 to afford an unusual tetracyclic ring system (Scheme ).…”