Conformational flexibility of antifungal atropisomeric strobilurin analogues: a quantum mechanical investigation

Quantum mechanical calculations were performed on novel N-phenyl-triazolone inhibitors of the mitochondrial bc1 complex. Both conformational flexibility and rotational barrier were examined. For all of the triazolones investigated, there is generally a large inter-ring torsion angle. The rotational barrier varies considerably among these analogues. For example, when a 6-methyl group is substituted on the phenyl ring at a position ortho to the triazolone, the calculated barrier is large enough to allow atropisomers to be stable even at room temperature. The calculated results are in agreement with experimental studies.