Synthesis of thalprzewalskiinone, a revision of structure

A direct comparison of the spectral data for synthetic 2-methyl-6,7-dimetho xy-3 ' -methoxy-4 ' -hydroxy-oxobenzylisoquinoline iodide (1) and its posit ional isomer 2-methyl-6,7-dimethoxy-3 ' -hydroxy-4 ' -methoxyoxobenzylisoqu inoline iodide (2) with the data obtained for the oxobenzylisoquinoline alk aloid thalprzewalskiinone revealed that the original structural assignment of the alkaloid as 1 was in error. These results mandate the revision of st ructure of thalprzewalskiinone to 2-methyl-6,7-dimethoxy-3 ' -hydroxy-4 ' - methoxyoxobenzylisoquinoline quinoline iodide (2).