151268-44-9Relevant academic research and scientific papers
1,3-dipolar cycloaddition to the Fe-O=C fragment (see abstract)
Siebenlist, Ron,Frühauf, Hans-Werner,Vrieze, Kees,Smeets, Wilberth J.J.,Spek, Anthony L.
, p. 5628 - 5641 (2008/10/08)
1,3-dipolar cycloaddition to the Fe-O=C fragment was investigated. First X-ray crystal structure of the initial bicyclo[2.2.1] adduct was also reported. The cycloaddition reaction of complexes with DMAD in the presence of PR3 (k: R = OMe; l: R = Ph) resulted without detectable intermediates in the formation of the Fe(CO)2PR3(butenolide) complexes.
1,3-Dipolar cycloaddition reactions to the C=X-M fragment. 9. Synthesis and characterization of mononuclear imino ketone complexes Fe(CO)3(t-Bu-N=C(H)-C(R)=O) and their use in chemoselective cycloaddition reactions with dimethyl acetylenedicarboxylate resulting in the formation of Fe(CO)3(butenolide) complexes
Van Wijnkoop, Maarten,Siebenlist, Ron,De Lange, Paul P. M.,Frühauf, Hans-Werner,Vrieze, Kees,Smeets, Wilberth J. J.,Spek, Anthony L.
, p. 4172 - 4181 (2008/10/08)
Reaction of Fe2(CO)9 at room temperature in THF with the α-imino ketones t-Bu-N=C-(H)-C(R)=O (R = Ph, Me) results in initial formation of mononuclear Fe(CO)3(t-Bu-N=C-(H)-C(R)=O (9) in moderate (9b: R = Me) to high (9a: R = Ph) yield. The σ-O, σ-N chelate coordination behavior of the heterodiene ligand in complexes 9 was confirmed by the spectroscopic data (IR, 1H and 13C NMR). With respect to their spectroscopic properties and chemical behavior the Fe(CO)3(α-imino ketone) complexes closely resemble the related Fe(CO)3(R-DAB) complexes. Under the conditions of their formation, complexes 9 undergo subsequent reactions with Fe(CO)n fragments or free ligand, giving rise to the formation of the stable dinuclear complexes Fe2(CO)6(t-Bu-N=C(H)-C(R)=O) (R = Ph, Me) and Fe2(CO)4(L-L) (10) (R = Me). Reaction of the mononuclear Fe(CO)3(t-Bu-N=C(H)-C(R)=O) complexes (9) with dimethyl acetylenedicarboxylate at -78°C under an atmosphere of CO results in the formation of the Fe(CO)3(butenolide) complexes (13a,b), which have been characterized both spectroscopically (IR, 1H and 13C NMR) and by elemental analysis. The solid state structure of complex 13b was determined by single-crystal X-ray diffraction. Crystals of 13b, C17H19NO9Fe, are triclinic, space group P1, with cell constants a = 8.627(1) A?, b = 9.597(2) A?, c = 11.557(1) A?, α = 81.60(1)°, β = 88.75(1)°, γ = 83.19(2)°, V = 939.8(2) A?3, Z = 2, R = 0.0405 (Rw = 0.0669) for 4165 unique reflections with I > 2.5σ(I). The coordination geometry around the central iron atom in 13b is distorted trigonal bipyramidal, with the intact σ-donating imine nitrogen and the η2-coordinated endocyclic C=C bond of the newly formed butenolide ligand occupying axial and equatorial positions, respectively. The proposed initial step in the formation of 13 is a chemoselective 1,3-dipolar cycloaddition of DMADC to the Fe-O=C fragment, yielding a bicyclo[2.2.1] intermediate 11. As opposed to the similar reactions of related M(CO)3(R-DAB) complexes, no intermediates can be observed in the present case, because the subsequent CO insertion into the Fe-O bond and the product forming reductive elimination of the newly formed Fe-C bonds are too fast even at very low temperatures.
