EFFORTS TOWARDS THE SYNTHESIS OF COMPONENTS OF THE SEX PHEROMONES OF Pectinophora gossypiella AND Sitotroga cerealella

Resumen

Pectinophora gossypiella and Sitotroga cerealella are pests occurring in economically important crops. The first occurs in cotton crop and the second in stored grains such as rice, wheat, corn and sorghum. Both are known for the damage they can cause and for their chemical control to be difficult in the larval phase, because they remain inside the cotton apples or grains, reducing contact with the applied products, whether chemical or biological insecticides. Alternatively, the use of pheromones for both monitoring and sexual confusion of these pests has shown good results with significant reduction in crop damage, thus becoming an important component within Integrated Pest Management (IPM). The pheromones of P. gossypiella, (Z,E)-7,11-hexadecadienyl acetate and (Z,Z) -7,11-hexadecadienyl acetate, and S. cerealella, (Z,Z)-7,11-hexadecadienyl acetate have been shown to be effective in controlling and monitoring these pests. The present work aims to synthesize the common intermediate to the routes of preparation of the pheromonal components of the two aforementioned pests: 2-(7-octinyloxy) tetrahydropyran. Its preparation began with 1,6-hexanediol monobromation, which was then protected with DHP. The protected bromoalcohol, 2-(6-bromoexyloxy)tetrahydropyran, was then alkylated with lithium acetylide in DMSO. 2-(7-Octinyloxy) tetrahydropyran was obtained in 43% yield. This terminal alkyne will be coupled with intermediates (E)-1-bromooct-3-ene for the preparation of the Z,E isomer, and 1-bromooct-3-in for the preparation of the Z,Z isomer. After coupling, hydroxyl deprotection with p-TsOH in methanol will then be performed, followed by Z-selective reduction with Lindlar catalyst in methanol and finally acetylation with acetic anhydride in pyridine.