1550-27-2Relevant articles and documents
Synthesis and in vitro antibacterial activity of 5-halogenomethylsulfonyl- benzimidazole and benzotriazole derivatives
Ochal, Zbigniew,Bretner, Maria,Wolinowska, Renata,Tyski, Stefan
, p. 1129 - 1136 (2014/01/06)
A series of 5-halogenomethylsulfonylbenzimidazole and benzotriazole derivatives was synthesized as potential antibacterial agents. A new method of synthesis of benzimidazoles was developed. The antimicrobial activities of these compounds were tested against a series of reference and clinical strains. The reference strains include Gram-positive bacteria (S. aureus, S. epidermidis, B. subtilis, B. cereus, E. hirae, M. luteus) and Gram-negative rods (E. coli, P. vulgaris, P. aeruginosa, B. bronchiseptica). The clinical strains include six methicillin-resistant (MRSA) and two methicillin-sensitive (MSSA) S. aureus strains, one methicillin-resistant S. epidermidis, three E. faecalis and two E. faecium strains. Compound with trifluoromethyl- substituent at C-2 position (4) displayed significant antibacterial activities comparable with nitrofurantoin against four strains, and higher against Micrococcus luteus. MIC values for clinical Staphylococci strains (MRSA) were 12.5-25 μg/mL; for Enterococcus strains these values were 50-100 μg/mL. MIC values for reference and clinical strains of Staphylococcus and Enterococcus group were similar, respectively.
Stereoelectronic and Conformational Effects in Meisenheimer Complexes. Intrinsic Reactivities of Spiro vs. 1,1-Dimethoxy and 1-Methoxy-1-phenoxy Complexes
Bernasconi, Claude F.,Howard, Keith A.
, p. 7248 - 7257 (2007/10/02)
Rate and equilibrium constants of formation of spiro Meisenheimer complexes derived from 1-(2-hydroxyethoxy)-2,6-dinitro-4-X-benzenes in aqueous solution are compared with those for 1,1-dimethoxy Meisenheimer complexes derived from 2,4-dinitro-4-X-anisoles.Hammett ρ values for the equilibrium constants are 8.2 for the dimethoxy and 5.9 for the spiro complexes, while the normalized ρ values for the rate constants of complex formation (cleavage) are 0.44 (-0.56) for the dimethoxy and 0.58 (-0.42) for the spiro complexes.The large difference in the equilibrium ρ values is attributed to a conformation of a dimethoxy complexes in which there is repulsion between the lone pairs on the ketal and the o-nitro group oxygens.A procedure for making the reactions in the two families thermodynamically comparable by correcting the rate and equilibrium constants for the pKa difference in the nucleophile and for intramolecularity of spiro complex formation was applied.The corrected parameters show that the spiro complexes form and decompose much faster than the dimethoxy complexes.This enhanced reactivity, ΔΔG, is attributed to a stereoelectronic effect or p-? overlap between a lone pair orbital of the nonreacting oxygen and the benzene ring, which is only feasible in the transition state of the spiro complex reaction (14) but not in the thransition state of the dimethoxy complex reaction (15).This interpretation is strongly supported by the fact that ΔΔG increases with increasing electron-withdrawing strength of X substituent.The enhanced rate of formation and decomposition of the spiro complex from catehol 2,4,6-trinitrophenyl ether compared to that of the corresponding 1-methoxy-1-phenoxy complex can be explained in a similar way.
