65731-84-2Relevant articles and documents
Stereoselective Degradation of alpha-Cypermethrin and Its Enantiomers in Rat Liver Microsomes
Yan, Jin,Zhang, Ping,Wang, Xinru,Xu, Meiqi,Wang, Yao,Zhou, Zhiqiang,Zhu, Wentao
, p. 58 - 64 (2016)
Alpha-cypermethrin (α-CP), [(RS)-a-cyano-3-phenoxy benzyl (1RS)-cis-3-(2, 2-dichlorovinyl)-2, 2-dimethylcyclopropanecarboxylate], comprises a diastereoisomer pair of cypermethrin, which are (+)-(1R-cis-αS)-CP (insecticidal) and (-)-(1S-cis-αR)-CP (inactive). In this experiment, the stereoselective degradation of α-CP was investigated in rat liver microsomes by high-performance liquid chromatography (HPLC) with a cellulose-tris- (3, 5-dimethylphenylcarbamate)-based chiral stationary phase. The results revealed that the degradation of (-)-(1S-cis-αR)-CP was much faster than (+)-(1R-cis-αS)-CP both in enantiomer monomers and rac-α-CP. As for the enzyme kinetic parameters, there were some variances between rac-α-CP and the enantiomer monomers. In rac-α-CP, the Vmax and CLint of (+)-(1R-cis-αS)-CP (5105.22 ± 326.26 nM/min/mg protein and 189.64 mL/min/mg protein) were about one-half of those of (-)-(1S-cis-αR)-CP (9308.57 ± 772.24 nM/min/mg protein and 352.19 mL/min/mg protein), while the Km of the two α-CP enantiomers were similar. However, in the enantiomer monomers of α-CP, the Vmax and Km of (+)-(1R-cis-αS) -CP were 2-fold and 5-fold of (-)-(1S-cis-αR)-CP, respectively, which showed a significant difference with rac-α-CP. The CLint of (+)-(1R-cis-αS)-CP (140.97 mL/min/mg protein) was still about one-half of (-)-(1S-cis-αR)-CP (325.72 mL/min/mg protein) in enantiomer monomers. The interaction of enantiomers of α-CP in rat liver microsomes was researched and the results showed that there were different interactions between the IC50 of (-)- to (+)-(1R-cis-αS)-CP and (+)- to (-)-(1S-cis-αR)-CP(IC50(-)/(+) / IC50(+)/(-) =0.61).
Abiotic enantiomerization of permethrin and cypermethrin: Effects of organic solvents
Qin, Sujie,Gan, Jianying
, p. 5734 - 5739 (2008/03/11)
All synthetic pyrethroids are chiral compounds, and isomerization has been frequently observed from exposure to certain solvents. However, so far, pyrethroid isomerization caused by solvents has not been characterized at the enantiomer level. In this study, we evaluated the occurrence of enantiomerization of two commonly used pyrethroids, permethrin and cypermethrin, in various organic solvents and solvent-water systems. The four stereoisomers of permethrin were stable under all test conditions. Rapid enantiomerization of cypermethrin was observed in isopropanol and methanol but not in n-hexane, acetone, or methylene chloride. After 4 days at room temperature, 18-39% conversions occurred for the different cypermethrin stereoisomers in isopropanol and methanol, and the enantiomerization invariably took place at the α-carbon position. The extent of enantiomerization was affected by temperature dependence and was also influenced by water as a cosolvent. In solvent-water mixtures, cypermethrin underwent gradual enantiomerization in acetone-water and rapid enantiomerization in isopropanol-water or methanol-water. The extent of enantiomerization varied among the solvents and as a function of the solvent-to-water ratio. Results from this study suggest that exposure to certain solvents and water may cause artifacts in chiral analysis and that for isomer-enriched pyrethroid products, such abiotic enantiomerization may render the products less effective because the conversion leads to the formation of inactive stereoisomers.
Stereospecific Total Synthesis of the Potent Synthetic Pyrethroid NRDC 182
Hatch, Charles E.,Baum, Jonathan S.,Takashima, Toshiyuki,Kondo, Kiyosi
, p. 3281 - 3285 (2007/10/02)
A highly stereospecific synthesis of (1R,3R)-cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid was devised which allowed for a total synthesis of the potent synthetic pyrethroid insecticide (S)-cyano-(3-phenoxyphenyl)methyl (1R,3R)-cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropancarboxylate (NRDC 182).Asymmetric reduction of 1,1,1-trichloromesityl oxide with an LAH-ephedrine complex produced (2R)-1,1,1-trichloro-2-hydroxy-4-methylpent-3-ene which was transformed to a diazoacetate ester via the corresponding diazoacetoacetate.Copper-catalyzed thermal decomposition of the diazoacetate resulted in internal carbenoid cyclization onto the olefin in nearly quantitative stereoselectivity.The resultant bicyclic lactone was ring opened via a Boord-type reaction to give the requisite cyclopropane acid which was esterified with racemic 3-phenoxybenzaldehyde cyanohydrin followed by recrystallization and epimerization of the mother liquor to produce NRDC 182.