A Plausible Mechanism for the Iridium-Catalyzed Hydrogenation of a Bulky N-Aryl Imine in the (S)-Metolachlor Process.
Molecules
; 27(16)2022 Aug 11.
Article
en En
| MEDLINE
| ID: mdl-36014344
ABSTRACT
The hydrogenation of N-(2-ethyl-6-methylphenyl)-1-methoxypropan-2-imine is the largest-scale asymmetric catalytic process for the industrial production of agrochemical (S)-metolachlor. The challenging hydrogenation across the sterically crowded carbon-nitrogen double bond was achieved using a mixture of [IrCl(COD)]2, (R,SFc)-Xyliphos, NBu4I and acetic acid. Acetic acid was critical in achieving excellent productivity and activity. Despite its industrial significance, a mechanism that explains how the sterically hindered bond in the imine is reduced has yet to be proposed. We propose a plausible proton-first, outer-sphere mechanism based on density functional theory calculations that is consistent with the experimentally observed activity and the enantioselectivity of the industrial process. Key findings include transition states involving acetate-assisted dihydrogen splitting, and a hydride transfer from a five-coordinate iridium trihydride directed by a C-HâââIr interaction. This article was submitted to a Special Issue in honor of Professor Henri Kagan.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Iminas
/
Iridio
Idioma:
En
Revista:
Molecules
Asunto de la revista:
BIOLOGIA
Año:
2022
Tipo del documento:
Article
País de afiliación:
Canadá