INSECTICIDAL 1,3-DITHIANES AND 1,3-DITHIANE 1,1-DIOXIDES

Replacement of the tert-butyl substituent of insecticidal cis- and trans-5-tert-butyl-2-(4-substituted-phenyl)-1,3-dithianes with cyclobutyl or 1-methylcyclopropyl groups affords compounds with equal or increased toxicity to houseflies. The 1,3-dithiane 1-oxides derived by m-chloroperoxybenzoic acid oxidation of the trans-dithianes are much less effective; unsynergized, their insecticidal activity is weak due to facile metabolic detoxification. The 1,3-dithiane 1-oxides similarly derived from the cis-dithianes generally exhibit a modest but significantly higher level of toxicity. Selective oxidation of the 1,3-dithiane 1-oxides with potassium permanganate afforded the corresponding 1,3-dithiane 1,1-dioxides, which alone and synergized with piperonyl butoxide are up to 11- and 37-fold more potent, respectively, than their parent dithianes. Housefly LD50s for trans-2(e)-(4-ethynylphenyl)-5(e)-(1-methylcyclopropyl)-1,3-dithiane 1,1-dioxide are 0.36 and 0.0095-mu-g/g alone and with piperonyl butoxide, respectively. It is the most insecticidal analogue in the dithiane series and is equal in potency to (1R)-cis-permethrin and to the most potent trioxabicyclooctane insecticides.