Erythromycin A oxime 11,12-carbonate and its oxime ethers.

Erythromycin A oxime 11,12-carbonate (5a) and its oxime ethers 5b approximately 5p have been prepared and their antibacterial activities compared with those of erythromycin A (1) and its 11,12-carbonate 2. The oxime 5a and many of its oxime ether derivatives showed good activity in vitro against Gram-positive and the more permeable Gram-negative organisms, in some cases being even more active than the carbonate 2.