The synthesis of the pyranonaphthoquinones dehydroherbarin and anhydrofusarubin using Wacker oxidation methodology as a key step and other unexpected oxidation reactions with ceric ammonium nitrate and salcomineDedicated to my friends and colleagues, Robin Giles and Ivan Green, who inspired me to research quinone chemistry.Electronic supplementary information (ESI) available: Copies of 1H and 13C NMR spectra are provided. CCDC 885420, 885421 and 885422. For ESI and crystallographic data in CIF o

The synthesis of two closely related pyranonaphthoquinones, dehydroherbarin and anhydrofusarubin, is described. The construction of the naphthalene nuclei was achieved using the Stobbe condensation reaction using 2,4-dimethoxybenzaldehyde and 2,4,5-trimethoxybenzaldehyde as their respective starting materials. Two key steps en route include a PIFA-mediated addition of a methoxy substituent onto the naphthalene skeleton and a Wacker oxidation reaction to construct the benzo[ g ]isochromene nucleus. Two interesting oxidation reactions of the intermediate isochromene enol ether of 7,9-dimethoxy-3-methyl-1 H -benzo[ g ]isochromene-5-ol were observed. Treatment of the substrate with salcomine resulted in the formation of (3-formyl-4-hydroxy-6,8-dimethoxynaphthalene-2-yl)methyl acetate, while treatment of the same substrate with CAN resulted in the formation of racemic (3 R ,4 R )-3-hydroxy-7,9-dimethoxy-3-methyl-5,10-dioxo-3,4,5,10-tetrahydro-1 H -benzo[ g ]isochromen-4-yl nitrate. The synthesis of two closely related pyranonaphthoquinones, dehydroherbarin and anhydrofusarubin, is described.