Abstract
Tylosin is a 16-membered macrolide antibiotic used as veterinary antimicrobial agent. In this paper, we describe the structure of a novel condensation product obtained by acidic hydrolysis and alkaline treatment of tylosin, as well as the isolation of the aglycone part, tylonolide 5, 20-hemiacetal, by application of a modified Polonovski reaction to tylosin. Furthermore, we describe syntheses of the intermediates of tylosin biosynthesis and of related compounds, and also the relationship between the structure and antimicrobial activity.