[H][H].[BrH:3].[CH3:4][NH:5][CH:6]1[CH2:15][CH2:14][C:13]2[C:8](=[CH:9][CH:10]=[C:11]([OH:17])[C:12]=2[OH:16])[C:7]1=[O:18]>O.[Pt](=O)=O>[BrH:3].[CH3:4][NH:5][CH:6]1[CH2:15][CH2:14][C:13]2[C:8](=[CH:9][CH:10]=[C:11]([OH:17])[C:12]=2[OH:16])[CH:7]1[OH:18]In 5 volume parts of water is dissolved 0.200 part of 3,4-dihydro-2-methylamino-5,6-dihydroxy-1(2H)-naphthalenone hydrobromide and, using 0.050 part of platinum dioxide, the catalytic reduction is carried out in a current of hydrogen gas until a substantially stoichiometric amount of hydrogen gas is absorbed. The catalyst in the reaction mixture is filtered off and to the filtrate is added a mixture of ethyl ether, methanol and water. The procedure gives white prisms of 2-methylamino-1,5,6-trihydroxy-1,2,3,4-tetrahydronaphthalene hydrobromide. Melting point: 165° to 169° C.(decomp.)
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