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3′-Deoxyseldomycin 5 (2), 2′-deamino-3′-epiamino-3′-deoxyseldomycin 5 (14), and 2′,3′-epimino-2′-deamino-3′-deoxyseldomycin 5 (15) were prepared from seldomycin 5 (1). Treatment of hexa-N-ethoxycarbonyl (ecb)-3′-O-tosylseldomycin 5 with sodium borohydride in DMSO gave the corresponding N-ecb-derivatives of 2, 14, and 15. Removal of the ecb groups of these compounds with aq potassium hydroxide gave the free bases 2, 14, and 15, respectively. Structure determination of the products was performed by means of MS, CMR, PMR, and chemical reactions. It was found that 2 exhibits a more potent and broader antibacterial activity than the parent compound 1, and 14 shows unique antibacterial spectrum against resistant strains, whereas 15 has almost no activity.

3′-Episeldomycin 5 (7) was synthesized from seldomycin 5. Reaction of hexa-N-ethoxycarbonylseldomycin 5 (2) with o-nitrobenzenesulfonyl chloride gave penta-N-ethoxycarbonylseldomycin 5-2′,3′-epicyclic carbamate (3) in one step. Hexa-N-ethoxycarbonyl-3′-O-tosylseldomycin 5 or hexa-N-ethoxycarbonyl-3′-O-mesylseldomycin 5, prepared from 2, was also converted into 3 by being heated in weakly basic solvents such as N,N-dimethylformamide or pyridine. Compound 3 was hydrolyzed to give 7. Structure of 7 was confirmed by PMR, CMR, MS, and Δ[M] values. Compound 7 was found to be active against resistant bacteria which carry 3′-O-phosphorylating enzymes. Δ[M] values for vicinal amino groups were shortly discussed.

3′-Episeldomycin 5 (7) was synthesized from seldomycin 5. Reaction of hexa-N-ethoxycarbonylseldomycin 5 (2) with o-nitrobenzenesulfonyl chloride gave penta-N-ethoxycarbonylseldomycin 5-2′,3′-epicyclic carbamate (3) in one step. Hexa-N-ethoxycarbonyl-3′-O-tosylseldomycin 5 or hexa-N-ethoxycarbonyl-3′-O-mesylseldomycin 5, prepared from 2, was also converted into 3 by being heated in weakly basic solvents such as N,N-dimethylformamide or pyridine. Compound 3 was hydrolyzed to give 7. Structure of 7 was confirmed by PMR, CMR, MS, and Δ[M] values. Compound 7 was found to be active against resistant bacteria which carry 3′-O-phosphorylating enzymes. Δ[M] values for vicinal amino groups were shortly discussed.