Kadethrin is used to control household pests, particularly houseflies,
mosquitoes and cockroaches. It is normally used in combination
with other pyrethroid insecticides and synergists.
Kadethrin is unstable to heat and it is rapidly decomposed by light. It
is hydrolysed in aqueous alkaline solution to (E)-(1R)-cis-2,2-dimethyl-3-
(2-oxothiolan-3-ylidenemethyl)cyclopropanecarboxylic acid (2), 5-benzyl-
3-furylmethanol (3) and its thiolactone ring-opened derivative (5)
(Scheme 1).
Products of photodecomposition have been reported by Ohsawa and
Casida (1979). Photo-hydrolysis of kadethrin occurs on sunlight irradiation
affording 2 and 5 and 5-benzyl-3-furancarboxylic acid (4), presumably
via the alcohol (3). cis-trans Isomerisation of the cyclopropane ring
and E-Z interconversion about the double bond was also noted. Thus,
from the lRcisE isomer (kadethrin), all of the possible isomers were found
to varying degrees (ie. 1RScis-trans-E-Z mixtures).
Photo-hydrolysis products (e.g. 2 and 5) were also found aS isomers.
The facility of the isomerisation process was considered to be due to
resonance stabilisation of a triplet diradical, one form of which (6) is
shown in Scheme 1. Kadethrin also yielded a lactone (7) derived from the
cyclopropane ring. Photo-oxidation of the alcohol moiety analogous to that reported for resmethrin was also found. The hydroxylactone (8) and
the benzyloxylactone (9) were reported (but the hydroxycyclopetenolone
[resmethrin, 61) was absent.
