Patent / 1972
Purification of 6-.alpha.-deoxy-5-hydroxytetracycline
The title antibiotic (I) prepd. by stereospecific hydrogenation of 11.alpha.-chloro-6-deoxy-6-demethyl-6-methylenetetracycline (II) or redn. of II with H2NNH2 in the presence of Pt or Pd/C catalysts was sepd. from the crude reaction mixts. by decompn. of the by-products with HCl at 68-75.degree., selective pptn. of I as the 5-sulfosalicylate, and treatment of the sulfosalicylate in EtOH with Et3N [or pptn. as mol. complex compd. with N,N'-dibenzylethylene-diamine or N,N'-dibenzylethylenediimine and sepn. of I from the complexes by suspension in EtOH and addn. of HCl]. Thus, the filtered hydrogenation product of 12,500 g II in DMF was washed with 50% aq. DMF, heated with 27.5 l. HCl at 68-72.degree., cooled to 50.degree., aq. 5-sulfosalicylic acid added and the mixt. kept 2 hr at 15.degree. to give 8,360 g I sulfosalicylate, a suspension of which in aq. EtOH was treated with Et3N-EtOH to give 95% I.