The stereospecificity at the iron center of the decarbonylation of an ironacetyl complex

Organometallic photochemistry at the end of its first century

“…We have noted above the aryl and alkyl migration from acyl ligands observed by King. In an important set of studies establishing the mechanism of these migration reactions, Wojcicki examined the decarbonylation and alkyl migration in enantiomerically pure (1-Me, 3-PhC 5 H 3 )Fe(CO)(PPh 3 )(C(‚O)Me) and found complete stereoretention in the products, Scheme 4 [22]. Similarly, decarbonylation of enantiomers of CpFe(CO)(PPh 3 )- (C(‚O)R * ) where R * is a chiral group, established that chirality was retained both at the R * and at iron [23].…”

Synthesis and characterization of methyl-phenyl-substituted cyclopentadienyl zirconium complexes

“…The 1 H and 13 C NMR spectra of both complexes are consistent with the behaviour expected for asymmetric molecules; complex 11 shows two singlets ( 1 H) and two signals ( 13 C) due to the non-equivalent Zr-methyls whereas four doublets ( 1 H) corresponding to diastereotopic methylenic protons and two methylenic signals ( 13 C) are observed for the two non-equivalent Zr-benzyl groups. One of the Zr-methyl singlets (11) and two of the Zr-methylene doublets (12) are substantially shifted highfield [d À0.12 (11), d 1.18, d 1.44 (12)] as expected for protons located under the anisotropic effect of the phenyl ring bound to the C b of the cyclopentadienyl ligand.…”

“…Although some stereochemical mechanistic studies on different transition metal complexes with the 1-phenyl-3-methyl-cyclopentadienyl ligand had been reported previously [11,12], this ligand was used [13] to prepare the first group 4 ansa-metallocenes with tetramethylethylene and dimethylsilyl bridges. Similar disubstituted tetrahydroindenyl compounds have been reported [14] recently.…”

Synthesis with Carbon Monoxide and a Petroleum Product

“…This could be explained by the change in the mode of addition of (25) or (26) and to a possible isomerization of the acylcobalt intermediates. Small variations in the reaction conditions may have a large influence on the product distribution.…”

“…Small variations in the reaction conditions may have a large influence on the product distribution. On the other hand, tricarbonylhydridocobalt would be more reactive at lower partial pressures of CO and the primary addition of (26) to the 1-alkene ensues in accord with the Markownikov rule (Scheme 4). 53 Under normal pressure of CO or nitrogen, extensive alkene isomerization and preferential formation of isoaldehyde are observed.…”