Iridium ferrocenyl diphosphine

The use of catalytic methods for the technical preparation of agrochemicals is illustrated by the case history of the herbicide metolachlor (trade name DUAL ), the most important herbicide for maize. The key step for the technical synthesis of the racemic conqx>und is a reductive alkylation catalyzed by a Pt/C catalyst in presence of sul ric acid. The commercial production of the biologically active S-enantiomers was made possible by the development of a new Iridium ferrocenyl-diphosphine catalyst system. Inqxirtant aspects of the development of the two catalyst systems as well as important prerequisites for the use of catalysts for the production of agrochemicals are discussed. 

Nowadays enantioselective synthesis of the herbicide (5)-metolachlor (Dual Magnum) is, to our knowledge, one of the most successful commercial applications of asymmetric C=N bond hydrogenation. Developed by Blaser and Spindler as a key step in the technical synthesis of (5)-metolachlor, the enantioselective hydrogenation of an imine intermediate 193 proceeds in the presence of an iridium ferrocenyl-diphosphine catalyst bearing a Solvias Josiphos-type chiral ligand (/ )-Xyliphos to give... 

Blaser H-U, Buser H-P, Jalett H-P, Pugin B, Spindler F. Iridium ferrocenyl diphosphine catalyzed enantioselective reductive alkylation of a hindered aniline. Synlett 1999 (1 Suppl) 867-868. 

Many chiral ferrocenyl diphosphines (Fig. 45) are effective for the rhodium-, iridium-, or ruthenium-catalyzed hydrogenation of dehydroamino acids and related compounds, as well as imines (145,166-172). 

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