CC Bond Formation of Alkenes with Isocyanates on Ni⁰ Complexes—a New Synthesis of Acrylamides

Abstract

The first metal‐induced synthesis of an acrylic acid derivative 4 from a non‐activated alkene 1 and an isocyanate 2 takes place via CC coupling to give an azanickelacyclopentanone 3. 4 is immediately formed upon heating 3.

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

“…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…”

Nickel-catalyzed coupling reactions of alkenes

“…Our attention was drawn to pioneering studies by Hoberg, who reported the stoichiometric and catalytic coupling reactions of phenyl isocyanate and ethylene on nickel(0) with trialkyl phosphine ligands, yielding N-phenylacrylamide [24][25]. A variety of other olefins, both activated and unactivated, have been reported to react with phenyl isocyanate with nickel(0) and phosphine ligands; the major product is the trans-disubstituted α,β-unsaturated amide [26].…”

Insertion of CO2-like molecules into the platinum–nitrogen bond of [Pt(PPh3)2(PhNO)]: the X-ray structures of [Pt{ON(Ph)C(NPh)S}(PPh3)2] and [Pt{ON(Ph)C(O)NPh}(PPh3)2]

“…[orthorhombic, space group Pbca, with a = 25.303 (8), b = 19.462 (6), c = 17.451 (5) A, and Z = 8; R = 0.075 for 2 001 reflections with I 2 3o(/)], while having confirmed that a C-N bond is formed within the co-ordination sphere of the metal, has shown that the entering molecule is bonded to platinum via nitrogen and not oxygen, as previously suggested. The difference in reactivity of PhN=C=S and PhN=C=O with complex (1) is discussed.…”