Synthesis of tricarbonyl(vinylallene)iron(0) complexes from tricarbonyl(vinylketene)iron(0) complexes and their oxidation to 5,5-disubstituted furan-2(5H)-ones

Saberi, Stephen P.; Thomas, Susan E.

doi:10.1039/p19920000259

Cited by 26 publications

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“…Conjugated dienes which are extended with a cumulated double bond, such as vinylketenes ( 1 ; X = O), also furnish η 4 -complexes with interesting structures 7 and reactivities . Although vinylallenes ( 2 ; X = C) are further examples of such cumulated-diene systems, their complexes have been rare; key examples have been limited to η 4 -iron carbonyl complexes prepared directly from a vinylallene and a phenylallene or indirectly via η 4 -vinylketene complexes …”

Section: Introductionmentioning

confidence: 99%

Coordination Modes and Catalytic Carbonylative [4 + 1] Cycloaddition of Vinylallenes

1999

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(Vinylallene)rhodium complexes with three kinds of coordination modes, that is, η 2-coordination of the terminal π-bond of the allenyl group, η 4-coordination of the conjugated diene skeleton, and planar σ 2-coordination, were synthesized by ligand substitution of RhCl(PPh3)3 with vinylallenes of specific substitution patterns. Their structures were determined by X-ray crystallography. Coordination preferences can be explained in terms of spatial interactions between the vinylallene substituents and the phosphine ligands as well as effective delocalization of the π-electrons of the endo- and exocyclic double bonds. The structural studies were extended to the development of the rhodium-catalyzed carbonylative [4 + 1] cycloaddition reaction of vinylallenes, affording five-membered carbocycles. With a nonsymmetrical vinylallene, face-selective η 4-coordination from the less hindered side of the allenyl group was observed. The achievement of [4 + 1] carbonylation can be attributed to (i) the substantial facility of substituted vinylallenes for η 4-coordination and (ii) the significant contribution of a metallacyclo-3-pentene resonance form to the intermediate complex. A platinum(0) complex also catalyzed the [4 + 1] cycloaddition of vinylallenes as efficiently as rhodium.

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