Revised structure of resorthiomycin.

Previously we reported the structure of a new antitumor antibiotic, resorthiomycin (I)1} with an SCH3group at C-6 and an acetyl group at C-l on the resorcinol nucleus (for numbering system, see Fig. 1). Based on the EI-MS and 13C NMRdata, Prof. Haruo Seto, University of Tokyo, suggested that the SCH3 group should not directly bind to the benzene ring and, instead, forms a methylthio ester at C-1 carbon, since the mass spectral fragmentation peak (M-SCH3)+ ofI and the long range ^C^H couplings observed between a methyl proton and three carbons (C-l, C-5 and C-6) were not