Structure Confirmation of the Four trans Isomers of Ceralure, a Medfly Attractant, by NMR

A series of one- and two-dimensional NMR experiments were used to confirm structures of the four racemic trans isomers of ceralure, ethyl 4-(or 5)-iodo-trans-2-methylcyclohexane-1-carboxylate, a synthetic attractant for the male Mediterranean fruit fly, Ceratitis capitata (Wiedemann). Proton and carbon assignments were made on the basis NMR data obtained from 2D chemical shift correlation maps, attached proton tests, and 2D- 1 H homonuclear correlation spectroscopy. Assignments of configuration and conformation, based on NMR, for the four trans isomers of ceralure (A, B 1 , B 2 , and C) were consistent with assignments previously derived from a comparison of the gas chromatographic elution behavior of the trans isomers of ceralure and the trans isomer of trimedlure, 1,1-dimethylethyl 4-(or 5)-chloro-trans-2-methylcyclohexane-1-carboxylate