Design, synthesis, and structure-activity relationship studies of conformationally restricted mutilin 14-carbamates

We report herein the design, synthesis, and structure-activity relationship studies of conformationally restricted mutilin 14-carbamates based on the structure of SB-222734. The antibacterial activities of these newly synthesized compounds were also evaluated and compared with linezolid and retapamulin. Results showed that most of the target compounds exhibit good potency in inhibiting the growth of Gram-positive bacteria including Methicillin-susceptible Staphylococcus aureus MSSA (MIC: 0.0625-2 μg/mL), Methicillin-resistant S. aureus MRSA (MIC: 0.0625-2 μg/mL), Methicillin-susceptible Staphylococcus epidermidis MSSE (MIC: 0.0625-2 μg/mL), Methicillin-resistant S. epidermidis MRSE (MIC: 0.0625-2 μg/mL), and Streptococcus pneumonia (MIC: 0.0625-4 μg/mL). In particular, three remarkable compounds of this series (12l, 12m, and 21l) exhibited comparable in vitro antibacterial profiles to that of retapamulin.