Ring-Modified Analogues and Molecular Dynamics Studies To Probe the Requirements for Fungicidal Activities of Malayamycin A and Its <i>N-</i>Nucleoside Variants

The importance of functional group orientations and the integrity of the bicyclic perhydrofuran core of malayamycin A and two equally active N-nucleoside analogues as fungicides were investigated. Two analogues 10 and 11, representing a THP-truncated and a bicyclic aza-variant, were synthesized and found to be inactive. Molecular dynamics studies on malayamycin A and analogues were performed to highlight the importance of properly orientating the urea and methyl ether groups.