Abstract

A process for the hydrogenation of a 6-methylenetetracycline in the production of alpha-6-deoxytetracycline, particularly the antibiotic doxycycline, in the presence of a transition metal complex of the formula MClx (PPh3)y wherein M is Cu, Co or Ni, x is 1 or 2 and y is 1-3, and a trace of rhodium either as the supported metal or as a rhodium salt, as a hydrogenation catalyst. The desired alpha-6-deoxytetracycline product is produced in high yields and stereospecificities. The process requires the use of substantially cheaper transition metal complexes and only traces of rhodium in the hydrogenation catalyst per mole of the 6-methylene tetracycline hydrogenated.

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