Synthesis and antibacterial activity of new 4″-O-carbamates of 11,12-cyclic carbonate erythromycin A 6,9-imino ether

A series of new 4″- O -carbamates of 11,12-cyclic carbonate erythromycin A 6,9-imino ether were synthesized and evaluated for their in vitro antibacterial activity. All the desired compounds demonstrated favorable activity (0.03 μg ml –1 ) against erythromycin-susceptible Streptococcus pneumoniae comparable to the references, exhibiting 133-fold higher activity than precursor 2 or 3 . Similarly, all of the analogs exhibited improved activity against the erythromycin-resistant S. pneumoniae encoded by the erm gene and the erm and mef genes, showing 4–32-fold more effectiveness than erythromycin A.