Stereochemistry of Insecticidal Organophosphorus Compounds

Shao yong Wu, Akinori Hirashima

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2 Citations (Scopus)


Aryl methyl phosphorochloridothionates (AMPC) were found as two-step phosphorylation reagents. The 4-nitrophenyl and 2,6-dichloro-4-methylphenyl derivatives (MNPC and CMPC) were resolved into optically active enantiomers to synthesize optical isomers of ten kinds of insecticidal 1,3,2-oxazaphospholidine 2-sulfides and two kinds of 1,3,2-benzodioxaphosphorin 2-sulfides, including the commercial insecticide salithion. of all the 4-substituted oxazaphospholidines, (5)c(i?)p isomers showed the highest insecticidal activity, followed by (S)c(S)p>{R)c{R)P>{R)c(S)p and for 5-phenyl oxazaphospholidine, {R)Q(R)p> (R)c(S)p> (S)c(i?)p> (5)c(5)p. (5) Configuration in the 4-substituted oxazaphospholidine and (R)c in the 5-phenyl derivative appear essential for a high insecticidal activity, consistent with land D-configuration of natural amino acids and octopamine, respectively. In the benzodioxaphosphorins, the (5)p configuration was favorable for a high insecticidal activity. The oxidative desulfurization of salithion by MCPBA produced an isomerized product (5-benzyl salithion) with racemization as well as the expected salioxon with retention of configuration. Bis(4-chloro-2-ethylphenyl) phenylphosphonate was metabolically transformed into the corresponding cyclic (predominantly cis) ester in houseflies in vivo. The (-(-)-enantiomer of sulprofos, resolved by acid-catalyzed ethanolysis of the diastereoisomer of proline derivative, was more toxic than (—)-enantiomer to houseflies. The chiral specificity was reversed relative to potency as inhibitor of housefly head AChE activity. Most of phosphorothiolates were activated to more potent inhibitors of electric eel AChE on coincubation with a mouse liver microsomal oxidase system. (—)-Sulprofos oxon sulfone was the exception, undergoing stereoselective detoxification when unwashed microsomes were used. Isofenphos was bio-activated by MFOs in two steps that ultimately gave N-desisopropyl isofenphos oxon, a product with 2300-fold greater inhibitory potency than isofenphos oxon toward housefly head AChE. The isofenphos isomers, resolved on a chiral HPLC column, had the same stereospecificity for MFO-activated anti-AChE activity and toxicity to houseflies, possibly due to enantiomeric differences in AChE inhibitory potency.

Original languageEnglish
Pages (from-to)527-534
Number of pages8
JournalJournal of Pesticide Science
Issue number3
Publication statusPublished - 1988

All Science Journal Classification (ASJC) codes

  • Insect Science
  • Health, Toxicology and Mutagenesis


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