Conformational and electronic study of sex pheromone of the pine processionary moth and some related derivative compounds with modification in the polar group

we report a conformational and electronic study of the sex pheromone of the pine processionary moth, thaumetopoea pytiocampa, the (z)-13-hexadecen-11-ynyl acetate (1) as well as the electronic properties of a few analogues, which were obtained by substitutions on the methyl group at the acetate function of the molecule (-oco-r with r= -ch3 (1); -ch2f (2); -cf3 (3); -ch2ch3 (4); -h (5); -ch2cl (6) and -ccl3 (7) ). analogue derivative (8) is also included, where -oco is substituted by -sco. an exploratory study of the conformational energy surface at compound 1 was carried out varying the torsion angles around c1-o, ( j1); o-c(=o), ( j2) and c9-c10, ( j3) bonds, using semiempirical methods. the structural and electronic parameters as atomic charges and orbital energies were calculated. total electronic charge density maps were also determined for the pheromone molecule and their analogue derivatives. the results obtained at semiempirical level of theory with am1 hamiltonian were related to the stereoelectronic requirements necessary to produce the activity on biological receptor, by comparative electroantennogram responses, eag.