6-Desoxy-tetracycline derivs. - made by hydrogenation of 6-methylene-tetracycline cpds. using rhodium tert. phosphine complex catalyst

摘要

6-desoxytetracyclines (I) are made by hydrogenation of a 6- methylenetetracycline of formula (II) in which Y is H or OH, or its acid addn. salt in the presence of a catalyst comprising a complex of rhodium and a tert. phosphine of formula PR1R2R3 in which R1 and R2 are each opt. substd. phenyl and R3 is opt. substd. phenyl, alkyl or benzyl, and the substituents on the phenyl gp. are alkyl, alkoxy or dialkylamino. The reaction is carried out in a solvent (III) in which both the (II) and the catalyst are soluble. Use of the tert. phosphine catalysts and solvent medium which dissolves the catalyst and reactant, gives prods. with a higher proportion of the alpha-isomer w.r.t. beta-isomer than prior processes such as that described in NL6802981.