| abstract |
ABSTRACT A process for the preparation of new stable homogeneous hydrogenation catalysts, comprising the reaction of a rhodium salt or complex with a hydra-zine, or a salt thereof, eventually in the presence of excess tertiary phosphi ne, and their application in very reduced quantities in improved processes for the stereoselective hydrogenation of 6-deoxy-6-demethyl-6-methylenetetracycli nes and for the simultaneous dehalogenation and stereoselective hydrogenation of 11a-chloro-6-deoxy-6-demethyl-6-methylenetetracyclines, to furnish .alpha.-6-deo xy-tetracyclines in high yields and purities. |