Hydrophobic acetal and ketal derivatives of mannopeptimycin-alpha and desmethylhexahydromannopeptimycin-alpha: semisynthetic glycopeptides with potent activity against Gram-positive bacteria.

The effect of introducing hydrophobic groups onto the disaccharide portion of the mannopeptimycins has been examined. Under acid-catalyzed conditions dimethyl acetals and ketals react on the terminal mannose of the disaccharide moiety of mannopeptimycin-alpha and the cyclohexylalanyl analogue 2. The preferentially formed monofunctionalized 4,6-acetals and -ketals display potent antibacterial activities against Gram-positive microorganisms, including MRSA, PRSP, and VRE pathogens.