Synthesis Of Avermectin B1a Derivatives And Their Bioactivity

The avermectins are a unique collection of naturally occurring macrocyclic lactones and they owned broad spectrum of anthelmintic and insecticidal activities. Their remarkable biological activity and complex molecular architecture stimulated significant interest in the scientific community. An enormous amount of research has been carried out on these molecules, and many modified derivatives have high bioactivities and have been commercially used.We have studied the protection of hydroxyl group at C-5 position using ally! chloroformate at the presence of the C-7 and C-4"-hydrooxyl groups and its deprotection. Studied the oxidation of the hydroxyl groups at C-4" and C-5 of avermectin Bla and synthesized five intermediate compounds> six derivatives of 5-deoxyavermectin Bla from 5-oxo-avermectin Bla by oxidation of the hydroxyl group at C-5-. two derivatives of 4"-deoxyavermectin Bla from 4-oxo-avermectin Bla by oxidation of the hydroxyl group at C-4".All the compounds' structures have been confirmed by IR 1H-NMR 13C-NMR and most of them also have been confirmed by MS. The substituted benzyloxyimino groups were introduced into avermectin B1a and the related methods of synthesis were studied. The spectra of the compounds were discussed and achieved an assignment of carbon resonance lines of all the compounds.The activities of the synthesized 5-deoxy-5-benzyloxyiminoavermectinBla derivatives were studied against Helicoverpa armigera and Spodoptera exigua. All compounds tested exhibited some insecticidal activities but lower than parent avermectin Bla...