The halofluorination reaction of a variety of alkenes by using tetrabutylammonium bifluoride (TBABF) in the presence of IV-halosuccinimide is described. This process occurs stereospecifically to afford anti addition products, and with unsymmetrical olefins a marked Markovnikov-type regioselectivity is observed. In some cases, formation of a remarkable amount of the corresponding dihalo derivatives was found, but this undesirable side reaction can be avoided by using N-iodosuccinimide (NIS) as halogenating agent. If jV-bromosuccinimide (NBS) or jV-chlorosuccinimide (NCS) is utilized, these dihalo compounds can be easily removed, from the halofluorinated compounds by simple column chromatography on silica gel. A mechanism for this side reaction is postulated.
New sulfur analogs of the sex pheromone of the female processionary mothThaumetopoea pityocampa have been found to be effective inhibitors of the natural pheromone activity both in EAG bioassays and field tests. The structures of these analogs have been derived from replacement of the oxygen atom(s) of the acetate group by sulfur (compounds 3-5) and the olefinic moiety of the enyne function by the isosteric SCH2 group (compounds 6 and 7). The synthesis and biological activity of 3-[(Z)-12-pentadecen-10-ynylthio]-1,1,1-trifluoropropan-2-one (8), a closely related structure to the pheromone is also described.
The synthesis and biological activity of some analogs of (Z)-13-hexadecen-11-ynyl acetate1, the major component of the sex pheromone of the processionary mothThaumetopoea pityocampa is described. The analogs have been formally derived by structural modification of the enyne and acetate functions of the parent compound1. In field tests, trifluoroacetate ester16 and the analog,11, with fluorine substitution at the olefin site, decreased the pheromone action, whereas epoxy derivative,10, from epoxidation of the olefin moiety in1, and propionate ester15 gave synergistic activity. The formate14 had a variable effect according to the composition of the lure. Formal reduction of the enyne to give the acetylene2 was found to retain activity. Alcohols12 and13, resulting from hydrolysis of the enyne1 and acetylene2, respectively, inhibited the action of their parent compounds.
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