With the help of chemical shifts computed with density functional theory (DFT), it is demonstrated that the reported experimental 13C NMR data of acremolin C are incompatible with the claimed structure of an N2,3-ethenoguanine with an isopropyl group at C-1'. An alternative structure, which is in agreement with both experimental and computed data, presents an isopropyl group at the C-2' position of an N2,3-ethenoguanine and leads to the conclusion that acremolin C is identical with acremolin B.
Keywords: 13C NMR spectroscopy; Marine fungi; N(2),3 ethenoguanines; computational chemistry; structural corrigendum.