| 摘要 |
A process for the preparation of the enantiomeric pairs (1R-3R- alpha S+1S-3S- alpha R) and (1R-3S- alpha S+1S-3R- alpha R) from a mixture of all 8 stereoisomers of the compound alpha R/S-cyano-3-phenoxy-4-fluorobenzyl 3R/S-(2,2-dichlorovinyl)-2,2-dimethyl-1R/S-cyclopropanecarboxylate, comprising dissolving the mixture in a secondary or tertiary alkylamine having 2-6 C atoms per alkyl radical, subjecting the solution to crystallization whereby the enantiomeric pairs (1R-3R- alpha S+1S-3S- alpha R) and (1R-3S- alpha S+1S-3R- alpha R) crystallize out from the solution, and separating the crystallized material. The crystals are enriched in the most active components. |
