Synthesis and insecticidal activity of bicyclic phosphorothionates and related monocyclic phosphorothionates [for plant protection]

Some thiono-type bicyclic phosphorus esters (BPs) were synthesized and bioassayed for insecticidal activity against susceptible (SRS) houseflies. n-Propyl was most favorable as a substituent at position 4 for insecticidal activity. The introduction of substituents at position 3 did not improve the activity. Some functionized monocyclic phosphorothionates (MPs) were also synthesized as proBP candidates. Although some MPs were cyclized to the corresponding BPs by oxidation or by action of a base, they did not show insecticidal activity. Some other MPs with a chloro-functionized 5-substituent had an insecticidal activity but their cyclization to the corresponding BPs was not yet proved.