Application of dibutyltin oxide method to regioselective acylation and alkylation of tylosin at C-4''.

4''-O-Acyl-, 4''-O-alkyl- and 4''-deoxy-tylosin derivatives were synthesized using 2'-O-acetyl-3'',4''-O-(dibutyl-stannio)tylosin as a synthetic intermediate. The in vitro biological evaluation showed that the new derivatives were active against macrolide-resistant clinical isolates of bacteria and mycoplasmas, and that they were resistant to hepatic esterase.