The Chiral Switch of (S)-Metolachlor: A Personal Account of an Industrial Odyssey in Asymmetric Catalysis

✍ Scribed by Hans-Ulrich Blaser

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 321 KB
• Volume: 344
• Category: Article
• ISSN: 1615-4150
• DOI: 10.1002/1615-4169(200201)344:1<17::aid-adsc17>3.0.co;2-8

✦ Synopsis

This account chronicles the various development phases of the Ir-catalyzed enantioselective hydrogenation for the production of (S)-metolachlor, the active ingredient of Dual Magnum ¾ (one of the most important grass herbicides for use in maize). The final process is today×s largest application of asymmetric catalysis and the Irxyliphos catalyst achieves unprecedented ton×s of 2,000,000 and tof values around 600,000 h À1 . The development started in 1982 and ended when the first production batch was run in November 1996. On the one hand, the paper recounts the various breakthroughs and set-backs and how the final catalytic system slowly evolved, and discusses on the other hand the strategies and approaches used for attaining the elusive goal. The various actions and decision points are analyzed and commented, and the roles and the seminal contributions of three key team members, Felix Spindler, Benoit Pugin, and Hans-Peter Jalett are presented.