Patent / 1972
Methacycline and doxycycline from 11a-chloro-6-deoxy-6-demethyl-6-methylenetetracycline
Methacycline (I) was prepd. by dechlorination of 11a-chloro-6-deoxy-6-demethyl-6-methylenetetracycline (II) with 1 mole H2NNH2 over Pd/C. With excess H2NNH2 and a Pt catalyst, II was dechlorinated and the methylene bond simultaneously reduced to give both I and doxycycline (II). II was used as, e.g., II.HF, II sulfosalicylate, or as II mol. complexes with N,N'-dibenzylethylenediamine or N,N'-dibenzyl-ethylenediimine. Thus, 10% Pd/C and 2 ml 15% H2NNH2.H2O were added to II.HF in EtOH. After 15 min 2.7 ml 15% H2NNH2.H2O was added. The mixt. was filtered and 5 g sulfosalicylic acid in H2O added to give 5.5 g I sulfosalicylate. Addn. of 2 ml 15% H2NNH2.H2O and 10% Pt/C to 5 g II.HF, further addn. of 6 ml H2NNH2.H2O at intervals, stirring the mixt. 3 hr, and addn. of 5 g sulfosalicylic acid and H2O gave 3.8 g crude sulfosalicylate contg. I 41, III 53, and III .beta.-isomer 4%.