FIELD: organic chemistry, antibiotics. SUBSTANCE: invention relates to a new method of synthesis of [4S-(4-alpha,12a-alpha)]-9-amino-4-(dimethylamino)-1,4,4a, 5, - -5a,6,11,12a-octahydro-3,10,12,12a-tetrahydro-1,11-dioxo-2- -naphthacenecarboxamide which is named further as 9-amino-6- -demethyl-6-deoxytetracycline and used for industrial synthesis of tetracyclines. Method involves interaction of 6-demethyl-6- -deoxytetracycline in cold concentrated sulfuric acid with halogenating agent at 0-20 C followed by interaction of the isolated 7-halogen-6-demethyl-6-deoxytetracycline with molar excess of nitrating reagent in concentrated sulfuric acid at (-15)-(+15) C. Synthesized 7-halogen-9-nitro-6-demethyl-6- -deoxytetracycline sulfate is reduced with catalysts on the basis of metals of VIII-group under pressure 0.07-2.81 kg/cm2 in solvent and treated with a mixture of isopropyl alcohol and diethyl ether at ratio 1:4. Method provides synthesis of very pure product, yield is 92-97%. EFFECT: improved method of synthesis, increased yield and purity. 7 cl, 4 ex
