Ethyl 4-[(1-substituted indol-2-yl)methoxy]benzoates and indoline derivatives: Anti-juvenile hormone and juvenile hormone activities

A number of ethyl 4-[(1-substituted indol-2-yl)methoxy]benzoates and indoline derivatives were prepared as rigid congeners of ethyl 4-(2-benzylhexyloxy)benzoate (KF-13), an anti-juvenile hormone (anti-JH) agent, and tested for both anti-JH and JH activities in silkworm larvae. In contrast to KF-13, the precocious metamorphosis-inducing activity of which decreased by increasing the applied doses, 1-n-propyl, 1-n-butyl (1c) and 1-benzyl (1d) derivatives were found to induce higher percentages of precocious metamorphosis at high doses. Compounds 1c and 1d also exhibited JH activity when topically applied to allatectomized 4th instar larvae. Ethyl 4-[(S)-(1-n-butylindolin-2-yl)methoxy]benzoate, which showed precocious metamorphosis-inducing activity at high doses, had no JH activity.