Hydrogen Doxycycline

Fig. 22 The asymmetric unit of doxycycline hyclate, showing two water molecules, one ethanol molecule, and two independent conformations of doxycycline. Hydrogen atoms are omitted for clarity (36).

Earlier work on the in situ characterisation of rhodium-phosphine/hydrazine complexes was instrumental in the successful outcome of patent litigation between Hovione (Portugal) and Pfizer (USA). Here, we were able to prove conclusively by P, N, and Rh NMR spectroscopies that in the hydrogenation of doxycycline to methacycline, rhodium complexes with N-donor ligands such as 3 and 4 were involved, rather than [RhCl(PPh3)3]." ... 

Catalytic uses of ihodacarbaboranes are represented in die stereoselective hydrogenation of methacycline to give doxycycline. The cluster [3,3-( n2,T]3.C7H7CH2)-c/oso-3,l,2-RhC2B9Hii] proves to be an effective catalyst for this xocess. ... 

Doxycycline (x), a hydrogenation product of nethacycliney was laarketed in the U S in Septeniber after a series of favorable clinical tests " disclosed high potency and efficient oral absorption for this more lipophilic chemical modification of oxytetracycline. 

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