Abstract: An improved method for preparing 2-chlorosulfinyl azetidine-4-one comprises heating a penicillin sulfoxide ester with an N-chlorohalogenating agent at a temperature of about 75.degree. C. to about 140.degree. in an inert organic solvent, and in the presence of an organic solvent insoluble, strongly basic ion exchange resin. Desirably, the ion exchange resin comprises a styrene-divinyl benzane copolymer which is about 2 to 16% cross-linked and incorporates a quaternary ammonium functionality. Such ion exchange resins are commercially available. The 2-chlorosulfinyl azetidine-4-one which is produced by this method can be cyclized in the presence of a Friedel-Crafts catalysts to afford the 3-exomethylene cepham sulfoxide ester in yields of 80-90%.

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 MCl.sub.x (PPh.sub.3).sub.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.

Abstract: A coordination compound useful as a hydrogenation catalyst, having the formula: ##STR1## wherein Ph is phenyl; R is hydrogen or C.sub.1 -C.sub.4 alkyl; and X is chloro, bromo or iodo. This compound is particularly useful as a homogeneous hydrogenation catalyst in the production of alpha-6-deoxytetracyclines, particularly the antibiotic doxycycline. The desired alpha-6-deoxy product is produced in high yields and stereospecificities, the process requiring the use of minimal quantities of rhodium metal in the hydrogenation catalyst per mole of the 6-methylenetetracycline hydrogenated.

Abstract: A coordination compound useful as a hydrogenation catalyst, having the formula: ##STR1## wherein Ph is phenyl; R is hydrogen or C.sub.1 -C.sub.4 alkyl; and X is chloro, bromo or iodo. This compound is particularly useful as a homogeneous hydrogenation catalyst in the production of alpha-6-deoxytetracyclines, particularly the antibiotic doxycycline. The desired alpha-6-deoxy product is produced in high yields and stereospecificities, the process requiring the use of minimal quantities of rhodium metal in the hydrogenation catalyst per mole of the 6-methylenetetracycline hydrogenated.

Abstract: A process for the hydrogenation of a 6-methylenetetracycline in the production of alpha-6-deoxytetracyclines, particularly the antibiotic doxycycline, in the presence of hydriodotetrakis (triphenylphosphine) rhodium (I) as a homogenous hydrogenation catalyst. The desired alpha-6-deoxy product is produced in high yields and stereospecificities, the process requiring the use of minimal quantities of rhodium metal in the hydrogenation catalyst per mole of the 6-methylenetetracycline hydrogenated.

Abstract: A coordination compound useful as a hydrogenation catalyst, having the formula: ##STR1## wherein Ph is phenyl; R is hydrogen or C.sub.1 -C.sub.4 alkyl; and X is chloro, bromo or iodo. This compound is particularly useful as a homogeneous hydrogenation catalyst in the production of alpha-6-deoxytetracyclines, particularly the antibiotic doxycycline. The desired alpha-6-deoxy product is produced in high yields and stereospecificities, the process requiring the use of minimal quantities of rhodium metal in the hydrogenation catalyst per mole of the 6-methylenetetracycline hydrogenated.