Tetronic acids are components of numerous natural products, 2 including chl~ rothricin,"~(-)- vertinolide, 6 ircinianin: hippospongin,'and ionophore M 139603, 8 of contemporary interest. The aci-reductone 2-hydroxytetronic acid system 1 found in chl~ rothricin~~~ and ascorbic acid2 has received considerably less attention. Discovery