Gloeosporone – A Macrolide Fungal Germination Self‐Inhibitor Total Synthesis and Activity

Starting with ( S )‐ or ( R )‐4‐Bromo‐1,2‐epoxybutane [commercially available or readily made from ( S )‐ or ( R )‐malic acid], both enantiomers of the germination self‐inhibitor gloeosporone were synthesized. The absolute configuration of the natural product was thus proven to be 4 S ,7 R ,13 R . Microbiological studies showed that both enantiomers of the compound cause inhibition of germination in spores of Colletotrichum gloeosporioides , and that (‐)‐gloeosporone is also active against a variety of other fungi. In order to gain some insight into the mode of action, 23 Na NMR measurements and ion‐selectivity studies were undertaken; none of these experiments provided evidence for a gloeosporone–metal ion interaction.