STRUCTURE-ACTIVITY-RELATIONSHIPS OF PYRIDYLCARBAMATES ACTIVE AGAINST BOTH BENZIMIDAZOLE-SENSITIVE AND BENZIMIDAZOLE-RESISTANT ISOLATES OF BOTRYTIS-CINEREA
T. Akagi et al., STRUCTURE-ACTIVITY-RELATIONSHIPS OF PYRIDYLCARBAMATES ACTIVE AGAINST BOTH BENZIMIDAZOLE-SENSITIVE AND BENZIMIDAZOLE-RESISTANT ISOLATES OF BOTRYTIS-CINEREA, Pesticide science, 44(1), 1995, pp. 39-48
A series of pyridylcarbamates showed high potency against cucumber gra
y mould (Botrytis cinerea Pers.). The most potent compound, propargyl-
N-(6-ethyl-5-iodo-2-pyridyl)carbamate was effective against an isolate
sensitive to benzimidazole and dicarboximide fungicides as well as ag
ainst an isolate resistant to both types of compound. QSAR analyses an
d molecular modelling studies were carried out to investigate the stru
ctural requirements for highly active compounds and the structural fea
ture of the binding site of each strain. Significantly different QSAR
equations were obtained only for substituents at the 6-position of the
pyridine ring. An ethyl-sized pocket or an ethyl terminal recognition
was suggested in the case of the sensitive or resistant isolate respe
ctively. These results could explain the phenomenon of negatively corr
elated cross-resistance between benzimidazoles and N-phenylcarbamate f
ungicides. Substituent effects at the 5- or 2-position were governed b
y steric factors. Substituent effects at the 3-position were explained
by steric hindrance or by conformational effects. The propargyl-subst
ituted compound above was the most desirable one from the viewpoint of
QSAR.