THEORETICAL-STUDY ON THE CONFORMATIONS OF 3-TIGLOYL-AZADIRACHTOL AND AZADIRACHTIN DERIVATIVES

Conformational and electronic studies of 3-tigloyl-azadiractol and oth er azadirachtin derivatives were carried out using molecular mechanics and AM1 calculations. A comparative analysis of the conformational ch aracteristics of 3-tigloyl-azadir-achtol, azadirachtin and its structu rally related derivatives was also performed. Our results indicate tha t the lack of antifeedant activity of 7-ketoazadirachtin and other ina ctive compounds can be explained on the basis of their different confo rmational behaviour. The conformationally restricted azadirachtin anal ogues provide us with crucial information about the optimal conformati onal requirement necessary to stimulate an antifeedant response.