METHOD FOR PREPARING 5,8-DIHYDROXY-2,6,7-TRIMETHOXY-3-ETHYL-1,4-NAPHTHOQUINONE Russian patent published in 2006 - IPC C07C50/32 

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for preparing 5,8-dihydroxy-2,6,7-trimethoxy-3-ethyl-1,4-naphthoquinone that represents a intermediate compound in synthesis of 2,5,6,7,8-pentahydroxy-3-ethyl-1,4-naphthoquinone (echinochrome A) that is active component of cardioprotective and ophthalmological preparation "Histochrome". 5,8-Dihydroxy-2,6,7-trimethoxy-2-ethyl-1,4-naphthoquinone is prepared by substitution of chlorine atoms with methoxy-groups in the chlorinated derivative of 1,4-naphthoquinone by effect with reagent MeOH-CsF-Al₂O₃ or MeOH-KF-Al₂O₃. As a derivative of 1,4-naphthoquinone method involves using 5,8-dihydroxy-2,6,7-trichloro-3-ethyl-1,4-naphthoquinone prepared by reduction of acetylhydroquinone, methylation of formed 1,4-dihydroxy-2-ethylbenzene, cycloacylation of prepared 1,4-dimethoxy-2-ethylbenzene with dichloromaleic anhydride followed by chlorination of prepared 5,8-dihydroxy-6,7-dichloro-3-ethyl-1,4-naphthoquinone. Invention provides simplifying method, diminishing fire hazard and enhanced yield of the end compound.

EFFECT: improved preparing method.