Abstract
The first successful demonstration of the amination of an olefin by a transition-metal-catalyzed N-H activation mechanism was accomplished in a stepwise manner with an Ir(I) catalyst and the substrates aniline and norbornylene. The initial N-H oxidative addition step envisioned in such a mechanism was demonstrated for the complexes Ir(PMe3)4PF6, Ir(PMe3)3(C8H14)Cl, and Ir(PEt3)3Cl, all of which gave rise to stable cis anilido hydride complexes when reacted with aniline. The second step olefin insertion, was accomplished from the reaction of Ir(PEt3)2(C2H4)2Cl (1) with aniline and norbornylene. The resulting insertion product, Ir(PEt3)2(NHPhC7H10)(H)Cl (6), was characterized by NMR spectroscopy and single-crystal X-ray diffraction and was found to have an azoiridacyclobutane type structure. The relevant crystal data for 6 are a = 10.702 (3) Å, b = 13.176 (21) Å, c = 19.498 (5) Å, β = 98.61 (2); P21/c, T = -70°C, dc = 1.591 g/cm3, μ = 51.21 cm-1; 3029 reflections, R = 0.039 and Rw = 0.036. Decomposition studies of 6 established two competing reaction pathways. C-N and Ir-C bond breaking, the microscopic reverse of the formation of 6, gave norbornylene and a reactive Ir intermediate. The competing pathway of C-H reductive elimination occurs by prior ligand dissociation and yields the amination product, exo-2-(phenylamino)norbornane (7). Labeling studies indicated an overall cis addition of the N-H group across the exo face of norbornylene. The individual steps for this reaction were elaborated into a catalytic cycle for the addition of aniline to norbornylene and a mechanism based on these individual steps proposed.
| Original language | English |
|---|---|
| Pages (from-to) | 6738-6744 |
| Number of pages | 7 |
| Journal | Journal of the American Chemical Society |
| Volume | 110 |
| Issue number | 20 |
| Publication status | Published - 1988 |
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Rational design in homogeneous catalysis. Ir(I)-catalyzed addition of aniline to norbornylene via N-H activation. / Milstein, David; Calabrese, Joseph C.; Milstein, David.
In: Journal of the American Chemical Society, Vol. 110, No. 20, 1988, p. 6738-6744.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Rational design in homogeneous catalysis. Ir(I)-catalyzed addition of aniline to norbornylene via N-H activation
AU - Milstein, David
AU - Calabrese, Joseph C.
AU - Milstein, David
PY - 1988
Y1 - 1988
N2 - The first successful demonstration of the amination of an olefin by a transition-metal-catalyzed N-H activation mechanism was accomplished in a stepwise manner with an Ir(I) catalyst and the substrates aniline and norbornylene. The initial N-H oxidative addition step envisioned in such a mechanism was demonstrated for the complexes Ir(PMe3)4PF6, Ir(PMe3)3(C8H14)Cl, and Ir(PEt3)3Cl, all of which gave rise to stable cis anilido hydride complexes when reacted with aniline. The second step olefin insertion, was accomplished from the reaction of Ir(PEt3)2(C2H4)2Cl (1) with aniline and norbornylene. The resulting insertion product, Ir(PEt3)2(NHPhC7H10)(H)Cl (6), was characterized by NMR spectroscopy and single-crystal X-ray diffraction and was found to have an azoiridacyclobutane type structure. The relevant crystal data for 6 are a = 10.702 (3) Å, b = 13.176 (21) Å, c = 19.498 (5) Å, β = 98.61 (2); P21/c, T = -70°C, dc = 1.591 g/cm3, μ = 51.21 cm-1; 3029 reflections, R = 0.039 and Rw = 0.036. Decomposition studies of 6 established two competing reaction pathways. C-N and Ir-C bond breaking, the microscopic reverse of the formation of 6, gave norbornylene and a reactive Ir intermediate. The competing pathway of C-H reductive elimination occurs by prior ligand dissociation and yields the amination product, exo-2-(phenylamino)norbornane (7). Labeling studies indicated an overall cis addition of the N-H group across the exo face of norbornylene. The individual steps for this reaction were elaborated into a catalytic cycle for the addition of aniline to norbornylene and a mechanism based on these individual steps proposed.
AB - The first successful demonstration of the amination of an olefin by a transition-metal-catalyzed N-H activation mechanism was accomplished in a stepwise manner with an Ir(I) catalyst and the substrates aniline and norbornylene. The initial N-H oxidative addition step envisioned in such a mechanism was demonstrated for the complexes Ir(PMe3)4PF6, Ir(PMe3)3(C8H14)Cl, and Ir(PEt3)3Cl, all of which gave rise to stable cis anilido hydride complexes when reacted with aniline. The second step olefin insertion, was accomplished from the reaction of Ir(PEt3)2(C2H4)2Cl (1) with aniline and norbornylene. The resulting insertion product, Ir(PEt3)2(NHPhC7H10)(H)Cl (6), was characterized by NMR spectroscopy and single-crystal X-ray diffraction and was found to have an azoiridacyclobutane type structure. The relevant crystal data for 6 are a = 10.702 (3) Å, b = 13.176 (21) Å, c = 19.498 (5) Å, β = 98.61 (2); P21/c, T = -70°C, dc = 1.591 g/cm3, μ = 51.21 cm-1; 3029 reflections, R = 0.039 and Rw = 0.036. Decomposition studies of 6 established two competing reaction pathways. C-N and Ir-C bond breaking, the microscopic reverse of the formation of 6, gave norbornylene and a reactive Ir intermediate. The competing pathway of C-H reductive elimination occurs by prior ligand dissociation and yields the amination product, exo-2-(phenylamino)norbornane (7). Labeling studies indicated an overall cis addition of the N-H group across the exo face of norbornylene. The individual steps for this reaction were elaborated into a catalytic cycle for the addition of aniline to norbornylene and a mechanism based on these individual steps proposed.
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M3 - Article
VL - 110
SP - 6738
EP - 6744
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 20
ER -