Heinz Hoberg
Max Planck Society
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Featured researches published by Heinz Hoberg.
Journal of Organometallic Chemistry | 1984
Heinz Hoberg; Dietmar Schaefer; Georg Dr. Burkhart; Carl Krüger; Maria João Romão
Abstract CO 2 and alkynes or alkenes undergo a 1/1 coupling in the presence of (Lig)Ni 0 complexes to give five-membered cyclic nickela complexes of types V and XVII. The influence of temperature and of the ligands upon the regioselectivity of the CC coupling in the case of monosubstituted olefins is reported, and the significance of these ring systems in preparative chemistry is emphasized. Oxanickelacyclopentenones (V) react with alkynes to form oxanickelacycloheptadienones (XIII). The structure of one of the compounds of this class has been determined by X-ray crystallography. Special features of these novel compounds, which can be readily prepared from CO 2 , are discussed together with the probable reaction mechanisms.
Journal of Organometallic Chemistry | 1983
Heinz Hoberg; Dietmar Schaefer
Abstract The nickel(0)-induced coupling of CO 2 with ethylene or with mono- or di-substituted alkenes is described. The regioselectivity of this reaction has been determined.
Journal of Organometallic Chemistry | 1983
Heinz Hoberg; Benno W. Oster
Abstract Diphenylacetylene and phenylisocyanate react with TMEDA/Ni 0 to give an azanickela-5-ring (IVa) which yields the azanickela-7-ring (IIb) with an activated alkyne. It is shown that both IVa and IIb are intermediates in the nickel-catalysed 2-pyridone synthesis. Pyrimidinediones are formed from diphenylacetylene and alkylisocyanates with TMEDA/Ni 0 .
Journal of Organometallic Chemistry | 1984
Heinz Hoberg; Dietmar Schaefer; Benno W. Oster
Abstract (Lig)Ni 0 systems react with 1,3-dienes in the presence of CO 2 to give nickela carboxylates. The influence of ligands and temperature on the regioselectivity of the CC bond formation is elucidated. In some cases the nickela carboxylates undergo reductive elimination under the influence of maleic anhydride, and the coupled diene/CO 2 moiety rearranges to give the diene carboxylic acid. A possible reaction sequence is discussed.
Journal of Organometallic Chemistry | 1984
Heinz Hoberg; Benno W. Oster
Abstract 1,2-Dienes react with CO 2 at nickel(O) under the influence of basic chelate ligands to form nickela carboxylates. The structures of these five-membered complexes have been determined by spectroscopic and chemical methods. The regioselectivity of the CC bond formation is discussed.
Journal of Organometallic Chemistry | 1982
Heinz Hoberg; Benno W. Oster
Abstract Azanickelacyclopenten derivatives, which can easily be prepared from alkynes, isocyanates and nickel(0) compounds, are shown to be intermediates in the nickel-catalysed synthesis of 2-pyridones.
Journal of Organometallic Chemistry | 1982
Heinz Hoberg; Dietmar Schaefer
Abstract The oxanickelacyclopentenone (I), formed from 2-butyne, CO 2 and nickel(0), reacts with activated alkynes by insertion to give oxanickelacycloheptadienones (II). It is suggested that these novel nickela complexes are intermediates in the nickel-catalysed synthesis of 2-pyrones from alkynes and CO 2 .
Journal of Organometallic Chemistry | 1977
Carl Krüger; Janine C. Sekutowski; Heinz Hoberg; Reinhild Krause‐Göing
The molecular conformations of a (pentaphenyl)aluminacyclopentadiene ligand (I) and its complex with 1,5-cycloactadienenickel (II) have been determined from single crystal X-ray data collected at room temperature with counter methods. The free ligand crystallizes in the monoclinic space group Cc with 4 molecules in a unit cell of dimensions a 10.5598(5), b 22.7089(12), c 13.3417(4) A, β 98.064(3)°; its (COD)Ni complex Crystallizes in the monoclinic space group P 2 1 / n with 4 molecules in a unit cell of the dimensions a 11.9948(8), b 16.9758 (13), c 18.7721(14) A. β 97.958(3)°. Both structures have been refined anisotropically to R values of 0.0577 and 0.0493, respectively. Upon complexation of I to the nickel atom the planarity of the ring system is distorted, with the aluminum being bent away from the nickel. A direct metal—metal interaction in II (NiAl: 2.748(1) A) cannot be ruled out.
Journal of Organometallic Chemistry | 1982
Heinz Hoberg; Dietmar Schaefer; Georg Dr. Burkhart
Abstract Oxanickelacyclopentene derivatives (I), which can easily be prepared from carbon dioxide, alkynes and nickel(0) compounds, are shovel to be versatile synthones. Some representative examples are given.
Journal of Organometallic Chemistry | 1991
Heinz Hoberg; Alfredo Ballesteros; Andrei Sigan; C. Jegat; Dieter Bärhausen; Armin Milchereit
Abstract Nickela-compounds with a five-membered ring, 4 , are formed on Ni 0 from CO 2 and alkenes in the presence of the heterodifunctional ligand (cyclo-C 6 H 11 ) 2 PCH 2 CH 2 -2-pyridyl ( 2 ). A ring contraction occurs on addition of a promoteor, such as BeCl 2 , or on heating. The greater reactivity of the nickela-complex with a four-membered ring, 6 , can be used in the former reactions with CO 2 , CO or CH 2 CH 2 . Such a sequence of reactions can be employed for the catalytic reaction of ethene with acrylic anilide on a (C 6 H 11 ) 3 P/Ni 0 system.