Synthesis and antibacterial activity of C2-fluoro, C6-carbamate ketolides, and their C9-oximes

Design, synthesis and structure-bactericidal activity relationships of novel 9-oxime ketolides and reductive epimers of acylides

Erythromycin was long viewed as a bacteriostatic agent. The erythromycin derivatives, 9-oxime ketolides have a species-specific bactericidal profile. Among them, the 3'-allyl version of the 9-oxime ketolide 1 (Ar=3-quinolyl; 17a) is bactericidal against Streptococcus pneumoniae and Streptococcus pyogenes. In contrast, the 2-fluoro analogs of 1, 13a (Ar=6-quinolyl), 13b (Ar=3-quinolyl) and 24a (Ar=4-isoquinolyl), show bactericidal activities against S. pneumoniae, Staphylococcus aureus and Moraxella catarrhalis, while the 2-fluoro analogs 13c (Ar=3-aminopyridyl) and 24b (Ar=3-carbamoylpyridyl) are only bactericidal against S. pneumoniae and Haemophilus influenzae. Reduction of the ketolides led to novel epiacylides, the 3-O-epimers of the acylides. Alteration of linker length (30b vs. 30a), 2-fluorination (33 vs. 30a) and incorporation of additional spacers at the 9-oxime or 6-OH (35, 40 vs. 30a) did not restore the epiacylides back to be as active as the acylide 31. Molecular docking suggested that epimerization at the 3-position reshapes the orientation of the 3-O-sidechain and leads to considerably weaker binding with bacterial ribosomes.

A new entry to the construction of a quaternary carbon center having a fluorine atom--S(N)2' reaction of γ-fluoroallylic alcohol derivatives with various cyanocuprates

Treatment of γ-fluoroallylic phosphate with various lower-ordered cyanocuprates derived from Grignard reagents, organolithium, and organozincs gave the corresponding S(N)2' products having a fluorine atom at a quaternary carbon center in excellent yields. This system could be successfully extended to the chiral version, enantiomerically pure fluorine-containing materials also being obtained in high yield.

Synthesis and antibacterial activity of C-12 pyrazolinyl spiro ketolides

A series of C-12 pyrazolinyl spiro ketolide derivatives were designed and synthesized. The C-12 modifications involved replacing the natural C-12 methyl group in clarithromycin core with different pyrazolinyl spiros via chemical synthesis. Potential anti-bacterial activities against both erythromycin-susceptible and erythromycin-resistant bacteria were reported.

Synthesis and antibacterial activity of 3-keto-6-O-carbamoyl-11,12-cyclic thiocarbamate erythromycin A derivatives

A series of 3-keto-6-O-carbamoyl-11,12-cyclic thiocarbamate erythromycin A derivatives has been synthesized. The best compounds in this series possess potent in vitro antibacterial activity against erythromycin-susceptible and erythromycin-resistant bacteria.

Synthesis and antibacterial activity of C6-carbazate ketolides

A novel series of ketolides containing heteroaryl groups that are linked to the erythronolide ring via a C6-carbazate functionality has been successfully synthesized. Careful modulation of the heteroaryl groups, the length and degree of saturation of the C6-carbazate linker, and the substituents present on each of the carbazate nitrogens led to compounds with potent activity against key bacterial respiratory pathogens. The best analogs of this series had in vitro and in vivo (sc dosing) profiles that were comparable to telithromycin.