Highly efficient nickel-catalyzed 2-methyl-3-butenenitrile isomerization: applications and mechanistic studies employing the TTP ligand family
A series of sterically and electronically fine-tuned, chelating diphosphine ligands were synthesized. The ligands are analogues of Triptyphos (TTP, 1), all based upon a variably 9,10-two-carbon-bridged 9,10-dihydroanthracene scaffold. These new TTP-type ligands were employed in the Ni(0)-catalyzed i...
Saved in:
| Main Authors: | , , , , , , |
|---|---|
| Format: | Article (Journal) |
| Language: | English |
| Published: |
21 April 2011
|
| In: |
Organometallics
Year: 2011, Volume: 30, Issue: 10, Pages: 2790-2809 |
| ISSN: | 1520-6041 |
| DOI: | 10.1021/om200164f |
| Online Access: | Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1021/om200164f
|
| Author Notes: | Michael E. Tauchert, Daniel C.M. Warth, Sebastian M. Braun, Irene Gruber, Alexandra Ziesak, Frank Rominger, and Peter Hofmann |
| Summary: | A series of sterically and electronically fine-tuned, chelating diphosphine ligands were synthesized. The ligands are analogues of Triptyphos (TTP, 1), all based upon a variably 9,10-two-carbon-bridged 9,10-dihydroanthracene scaffold. These new TTP-type ligands were employed in the Ni(0)-catalyzed isomerization of 2-methyl-3-butenenitrile (2M3BN), one of the key steps of industrial adiponitrile production by the DuPont process. The reaction showed a surprising preference for ligands bearing electron-donating substituents, such as methoxy or methyl groups, in the phenyl para position of the Ni-ligating PPh2 units. Octyltriptyphos (3) afforded the highest 2M3BN-isomerization turnover rate yet reported. A series of deuterium-labeling experiments was performed to investigate the possibility of an isomerization mechanism consisting of a cascade of de- and rehydrocyanation steps, which could be excluded. Using the ethano-bridged ligand 4, complex 16a (4-κP:κP′)Ni(η3-C4H7)CN (supposedly an intermediate of the 2M3BN-isomerization reaction) was isolated, and its solid-state structure was determined by X-ray diffraction analysis. The complete catalytic cycle of 2M3BN isomerization with ligand 4, as suggested by the available experimental evidence, was modeled using DFT methods. |
|---|---|
| Item Description: | Gesehen am 26.10.2022 |
| Physical Description: | Online Resource |
| ISSN: | 1520-6041 |
| DOI: | 10.1021/om200164f |