Synthesis and anti-juvenile hormone activity of ethyl 4-(2-(6-methyl-3-pyridyloxy)alkyloxy)benzoates

A series of ethyl 4-[2-(6-methyl-3-pyridyloxy) alkyloxy] benzoates was prepared and tested for activity to induce precocious metamorphosis in larvae of the silkworm, Bombyx mori. Of the compounds tested ethyl 4-[4-methyl-2-(6-methyl-3-pyridyloxy) pentyloxy] benzoate (5) was the most effective when applied to 24 hr-old 3rd instar larvae. There was no significant difference in precocious metamorphosis-inducing activity between 5R(+)- and 5S(-)-enatiomers. The activity of compound 5 could be fully counteracted by methoprene, a juvenile hormone, (JH) agonist, but not by the dietary administration of 20-hydroxyecdysone. When 3rd instar larvae were treated with compound 5, hemolymph JH esterase activity, which is indispensable for the initiation of pupation in normal last instar larvae, was induced during the 4th instar.