| 摘要 |
PURPOSE: A process for preparing ivermectin which permits simple removal both of the rhodium employed and of the organic components of the catalyst system from the product solution which is obtained after the hydrogenation to give an active compound which can be processed with low loss of material to give a form suitable for use, is provided. CONSTITUTION: A process for preparing ivermectin, characterized in that mixtures of avermectin B1a and B1b are reacted by selective hydrogenation with a catalyst in a reaction solvent wherein the catalyst is selected from the group consisting of rhodium salts and rhodium-phosphine complexes wherein said catalyst is optionally derivatized with hydrazine or a hydrazine salt and the phosphine is defined by formula (I) in which R, R' and R" independently of one another each represent hydrogen, alkyl or optionally alkyl-, alkoxy-, halogen- or halogenalkyl-substituted arylalkyl, A, A' and A" independently of one another each represent optionally alkyl- or alkoxy- and/or optionally halogen- or halogenoalkyl-substituted divalent aromatic radicals, m1, m2 and m3 are identical or different and are each 0 or 1, the sum of the carbon atoms present in the alkyl and alkoxy groups being at least 12, to give ivermectin, and the catalyst system is subsequently removed from the resulting recation mixture by extraction with a lipophilic solvent wherein the extraction step is optionally performed after the removal of the reaction solvent.
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