Absolute configuration of Cecropia juvenile hormone

The absolute configuration of the predominant Cecropia hormone, methyl 12,14-dihomojuvenate, has been determined to be methyl (E,E)-(10R,11S)-(+)-10,11-epoxy-7-ethyl-3,11-dimethyl-2, 6-tridecadienoate (I). The less abundant hormone, methyl 12-homojuvenate, can be presumed by analogy to have the corresponding 3,7,11-trimethyldienoate structure (II). The assignment has been established with microamounts of substance by applying Horeau's method to the glycol derivative (III) of the hormone.The course of the perchloric acid-catalyzed epoxide ring opening of I was checked by conducting the conversion in (18)O-labeled water. It has been ascertained that the configuration at the secondary hydroxyl group of the resulting III remained unchanged. On the other hand, the hydration proceeded with a surprisingly high rate of cis opening.