Antimicrobial properties of highly fluorinated tris(pyrazolyl)borates

Highly fluorinated tris(pyrazolyl)borates were tested for their antimicrobial activity against various bacterial species. Both the silver(I) tris(pyrazolyl)borate [HB(3,5-(CF(3))(2)Pz)(3)]Ag(THF) (THF=tetrahydrofuran) and the sodium analog [HB(3,5-(CF(3))(2)Pz)(3)]Na(THF) appeared highly effective at inhibiting the growth of two different species of Gram-positive bacteria (i.e. being 12 and 21 fold more effective, respectively, (on a molar basis, based on the minimum inhibitory concentrations) against Staphylococcus aureus than silver sulfadiazine, a currently used silver antimicrobial). This suggests that the ligand portion of these molecules is responsible for the observed high effectiveness against the Gram-positive species. Furthermore, it appeared that the fluorinated substituents on the tris(pyrazolyl)borate were important for this high level of growth inhibition. Against two species of Gram-negative bacteria, including Pseudomonas aeruginosa, the fluorinated silver(I) tris(pyrazolyl)borate exhibited a moderate level of growth inhibition (similar to that of silver sulfadiazine), while the sodium analog showed very little ability to inhibit growth, indicating that for the Gram-negative species, the apparent responsible antimicrobial portion is the silver ion.     

Revisiting the aldol reaction of cis-α,β-epoxyaldehyde promoted by BF(3)·Et(2)O: direct access to 2-deoxy-2-fluoro heptulosonic ester analogues

The aldol reaction between cis-3-((tert-butyldiphenylsilyloxy)methyl)oxirane-2-carbaldehyde and ethyl-2-(trimethylsilyloxy)-2-propenoate promoted by boron trifluoride diethyl etherate was reinvestigated. By varying the work-up conditions, a new 2-deoxy-2-fluoro heptulosonic ester analogue was synthesized. Derivatizations and detailed NMR analysis allowed the complete characterization of this fluoro analogue and its derivatives.     

Rapid synthesis of 2′,3′-dideoxy-3′β-fluoro-pyrimidine nucleosides from 2′-deoxypyrimidine nucleosides

A rapid synthesis of 2′,3′-dideoxy-3′-fluoro-β-d-threo-nucleosides bearing the pyrimidine canonical bases of nucleic acids has been developed in order to discover new nucleoside derivatives as potential antiviral drugs. However, when evaluated for their antiviral activity in cell culture experiments, none of these compounds showed any significant antiviral activity.     

Synthesis and Antiviral Evaluation of 2′,3′-Dideoxy-2′-fluoro-3′-C-hydroxymethyl-β-D-arabinofuranosyl Pyrimidine Nucleosides

Abstract

The synthesis and anti-HBV and anti-HIV activity of a number of 2′,3′-dideoxy-2′-fluoro-3′-C-hydroxymethyl-β-D-arabinofuranosyl pyrimidine nucleosides are reported.     

Synthesis of trifluoroborate functionalised imidazolium salts as precursors to weakly coordinating bidentate NHC ligands

A new class of trifluoroborate functionalised N-heterocyclic carbene precursors have been synthesised, isolated and characterised structurally. The ligands were obtained via a serendipitous one-pot reaction in which deprotection, cyclisation and fluorination of boryl-functionalised diarylethylenediamine derivatives occur concurrently. Deprotonation of the imidazolium salts was found to yield the free carbene, though 18-crown-6 was found necessary to prevent further reactivity of the resulting aryl potassium trifluoroborate salts; in the absence of 18-crown-6, elimination of KF resulted in a cyclic carbene-BF₂ arene adduct. Complexation to rhodium was facile, and yielded four-coordinate complexes in which the Rh-BF₃ interaction was determined by ¹⁹F NMR spectroscopy to be weak.