Synthesis of pyrethroic acids from natural products and from isomeric compounds: Strategy and practice

Synthesis of New Spiro-Cyclopropanes Prepared by Non-Stabilized Diazoalkane Exhibiting an Extremely High Insecticidal Activity

The synthesis of new insecticidal gem-dimethyspiro-cyclopropanes derived from pyrrolidine-2,3-dione have been described, and their biological effect against different insect species has been evaluated. The presented results demonstrate the excellent insecticidal activity of cyclopropane 5c against Aedes aegypti and Musca domestica. Cyclopropane 5c showed the quickest knockdown and the best killing against Aedes aegypti and Musca domestica compared to trans-chrysanthemic acid and pyrethrin. The biological results of the high insecticidal activity were confirmed by the results of docking. This is evident in the binding affinity obtained for cyclopropane 5c, indicating good binding with an important active amino acid residue of the 5FT3 protein.

Direct high-performance liquid chromatographic method for enantioselective and diastereoselective determination of selected pyrethroic acids

This study reports on the direct HPLC stereoisomer separation of selected pyrethroic acids employing commercial cinchona alkaloid derived chiral stationary phases (CSPs). cis/trans-Chrysanthemic acid (cis/trans-CA), cis/trans-chrysanthemum dicarboxylic acid (cis/trans-CDCA), cis/trans-permethrinic acid (cis/trans-PA), and fenvaleric acid (FA) were resolved into the individual stereoisomers, i.e. enantiomers and diastereomers as well. To achieve satisfactory baseline separation an optimisation of the variables of the chromatographic method including chemical structure of the cinchona carbamate CSP, mobile phase composition, and flow rate was required. All four stereoisomers of PA were successfully separated in a single run (alphacis = 1.20, alphatrans = 1.26, critical Rs = 1.65) with an acetonitrile (ACN)-based polar-organic eluent. The complete baseline resolution of all CA stereoisomers succeeded in polar-organic (alphacis = 1.20, alphatrans = 1.35, critical Rs = 3.03) as well as in acetonitrile-based reversed-phase media (alphacis = 1.24, alphatrans = 1.22, critical Rs = 2.73). The latter elution mode was also found to be suitable for the enantio- as well as diastereoselective resolution of CDCA (alphacis = 1.09, alphatrans = 1.50, critical Rs = 1.43), which is to the best of our knowledge the first reported enantiomer separation of this analyte. The enantiomers of FA could be baseline separated employing also reversed-phase mode (alpha = 1.16, Rs = 2.91). These separation methods may be applied for quality control processes in the production of stereoisomerically pure insecticides as well as stereoselective toxicokinetic studies, as CDCA, PA, and FA are suitable biomarkers for monitoring human pyrethroid burden.