METHOD OF PRODUCING 6,7-SUBSTITUTED 2,3,5,8-TETRAHYDROXY-1,4-NAPHTHOQUINONES (SPINAZARINS) Russian patent published in 2013 - IPC C07C50/32 C07C46/00 

FIELD: chemistry.

SUBSTANCE: present invention relates to a method of producing 6,7-substituted derivatives of 2,3,5,8-dihydroxy-1,4-naphthoquinone (spinazarins) of formula I where R₁ and R₂ both simultaneously denote H, Me, Cl, or R₁=H, and R₂=Me, Et, t-Bu, Cl, OMe; R₁=Me, and R₂=Cl, OMe, OEt, OH; R₁=Et, and R₂=Cl, OMe, OEt, OH, which can be used in medicine and cosmetology. The disclosed method is realised by heating 6,7-substituted 3-amino-2,5,8-trihydroxy-1,4-naphthoquinone of formula II where R₁ and R₂ both simultaneously denote H, Me, Cl; or R₁=H, and R₂=Me, Et, t-Bu, Cl, OMe; or R₂=H, and R₁=Me, Et, t-Bu, Cl, OMe; or R₁=Me, and R₂=Cl, OMe, OEt; or R₂=Me, and R₂=Cl, OMe, OEt, OH; or R₁=Et, and R₂=Cl, OMe, OEt; or R₂=Et, and R₁=C1, OMe, OEt, OH, in a reaction mixture of formic acid, water, sulphuric acid and dimethylsulphoxide, the reactants being in weight ratio of 40:7:3:2, respectively, at temperature of 90-110°C, preferably at boiling point under reflux for 10-30 minutes.

EFFECT: method increases output of the desired spinazarins and cuts duration of the process.

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