Diastereomer Separation by Formation of Inclusion Compounds: 2,6‐Dimethylnaphthalene Complexes of Flumethrin

The separation of the inactive flumethrin isomer from a technical mixture of this insecticide and acaricide was achieved by forming an inclusion complex. The composition of the commercial formulation can thus be enriched in the active diastereomer and dosages can be reduced. X‐ray crystallography reveals that adducts of type 1 are formed. Electron donor–acceptor interactions are probably the controlling factor in the formation of 1.