CC‐Verknüpfung von Alkenen mit Isocyanaten an Ni⁰‐Komplexen – eine neue Synthese von Acrylsäureamiden

Abstract

Die Additionsfahigkeit der Ni-C-o-Bindung in 1 gegeniiber CC-Mehrfachbindungssystemen ist ebenfalls schon bei 20°C sehr ausgeprlgt. So wird nach Zugabe von Allen zu einer THF-Losung von 1 durch Insertion der q3-Allylkomplex 4 gebildet [95%; Fp=82"C (Zers.); Ir (KBr): v= 1635 (C=O), 3130 cm-' (N-H)]. 4 laat sich zu N,N-

The First Catalytic Synthesis of an Acrylate from CO2 and an Alkene—A Rational Approach

“…Precipitation by addition of n-hexane (50 mL), filtration, and drying under vacuum yielded compound 2 e as a fine, yellow precipitate (164 mg, 73 % yield). Orange crystal (plate); dimensions: 0.23 0.19 0.07 mm 3 ; crystal system: triclinic; space group: P1 ; Z = 2; a = 9.7498 (11) 8 ]THF (0.6 mL) and placed in an HP NMR tube. The NMR tube was consecutively pressurized with ethylwww.chemeurj.org ene (2 bar) and CO 2 (6 bar) to an overall pressure of 8 bar and then heated to 25 (1 d) (138 mg, 500 mmol), dtbpe (159 mg, 500 mmol), and the internal standard tetrabutylphosphonium tosylate (108 mg, 250 mmol) were dissolved in THF (15 mL) and added to an autoclave (60 mL) by using a charger.…”

“…Hoberg et al and others [5,6,7,8] have revealed metallalactones, in particular nickelalactones ("Hoberg complexes"), [9] to be stable and isolable intermediates of the potential catalytic coupling of ethylene and CO 2 , but it has never been possible to assemble the elementary reactions of the putative catalytic cycle proposed by Walther et al, [10] nor has it been possible to actually close the catalytic cycle itself. Despite the development of a catalytic route to the structurally similar acrylamides from alkenes and isocyanates (isoelectronic to CO 2 ), [11] and an intensive search for other catalytically active metals from the nickel (Pd, Pt) [12,13] and iron triads, [14] the basic obstacles for a catalytic transformation have not been overcome; the prohibitive overall thermodynamic situation for the production of acrylic acid (DG = + + 42.7 kJ mol À1 ), [15] the limitation to a small set of ligands, the unproductively low reaction temperatures (down Keywords: C 1 building blocks · carbon dioxide fixation · carboxylation · homogeneous catalysis · nickel Abstract: For more than three decades the catalytic synthesis of acrylates from the cheap and abundantly available C 1 building block carbon dioxide and alkenes has been an unsolved problem in catalysis research, both in academia and industry. Herein, we describe a homogeneous catalyst based on nickel that permits the catalytic synthesis of the industrially highly relevant acrylate sodium acrylate from CO 2 , ethylene, and a base, as demonstrated, at this stage, by a turnover number of greater than 10 with respect to the metal.…”

“…and others5, 6, 7, 8 have revealed metallalactones, in particular nickelalactones (“Hoberg complexes”),9 to be stable and isolable intermediates of the potential catalytic coupling of ethylene and CO 2 , but it has never been possible to assemble the elementary reactions of the putative catalytic cycle proposed by Walther et al.,10 nor has it been possible to actually close the catalytic cycle itself. Despite the development of a catalytic route to the structurally similar acrylamides from alkenes and isocyanates (isoelectronic to CO 2 ),11 and an intensive search for other catalytically active metals from the nickel (Pd, Pt)12, 13 and iron triads,14 the basic obstacles for a catalytic transformation have not been overcome; the prohibitive overall thermodynamic situation for the production of acrylic acid (Δ G =+42.7 kJ mol −1 ),15 the limitation to a small set of ligands, the unproductively low reaction temperatures (down to −70 °C), and the failure of the Hoberg‐type complexes (and of other metallalactones) to undergo a productive cleavage (believed to occur, for example, through a β ‐hydride elimination) have made this reaction a difficult object to study 16…”

Acetylene and Ethylene: Universal C2 Molecular Units in Cycloaddition Reactions

“…Therefore, the sequential reaction of isocyanates, ethylene, and carbon monoxide under nickel catalysis afforded succinimides in good yields. 13h The process included two steps: firstly formation of nickel complex 220 from the Ni(0) compound, isocyanate, and ethylene, and secondly reaction of 220 with carbon monoxide to give succinimide 221 in 71% yield (Scheme 98 ). 13h…”

“…13h The process included two steps: firstly formation of nickel complex 220 from the Ni(0) compound, isocyanate, and ethylene, and secondly reaction of 220 with carbon monoxide to give succinimide 221 in 71% yield (Scheme 98 ). 13h…”