IDENTIFICATION AND SYNTHESIS OF PRODUCTS ISOLATED DURING METABOLISM STUDIES OF TILMICOSIN

Two substances, designated T-1 and T-2, were isolated during metabolis m studies with tilmicosin, a new veterinary macrolide antibiotic. By c ombination of mass spectrometry and NMR spectroscopy, T-1 was identifi ed as N-demethyltilmicosin and T-2 was assigned a dimeric structure re sulting from reductive coupling of desmycosin with T-1. T-1 was synthe sized by selective N-demethylation of tilmicosin, using K3Fe(CN)(6) in aqueous 2-propanol. T-2 was synthesized by reductive amination of des mycosin with T-1 using NaBH3CN. The synthetic compounds were identical with the respective isolated materials, thereby confirming the struct ural assignments for both compounds.