Fullerene bisadduct regioisomers containing an asymmetric diamide tether

Synthesis of Carbapenems Containing Peptidoglycan Mimetics and Inhibition of the Cross-Linking Activity of a Transpeptidase of l,d Specificity

The carbapenem class of β-lactams has been optimized against Gram-negative bacteria producing extended-spectrum β-lactamases by introducing substituents at position C2. Carbapenems are currently investigated for the treatment of tuberculosis as these drugs are potent covalent inhibitors of l,d-transpeptidases involved in mycobacterial cell wall assembly. The optimization of carbapenems for inactivation of these unusual targets is sought herein by exploiting the nucleophilicity of the C8 hydroxyl group to introduce chemical diversity. As β-lactams are structure analogs of peptidoglycan precursors, the substituents were chosen to increase similarity between the drug and the substrate. Fourteen peptido-carbapenems were efficiently synthesized. They were more effective than the reference drug, meropenem, owing to the positive impact of a phenethylthio substituent introduced at position C2 but the peptidomimetics added at position C8 did not further improve the activity. Thus, position C8 can be modified to modulate the pharmacokinetic properties of highly efficient carbapenems.

Analytical and preparative separation and isolation of functionalized fullerenes by conventional HPLC stationary phases: method development and column screening

Isolation and purification of functionalized fullerenes from often complex reaction mixtures is challenging due to the hydrophobic nature and low solubility in regular organic solvents. We have developed an HPLC method that efficiently, employing regular reversed phase stationary phases, separates not only C₆₀ from C₇₀ in a model mixture, but also C₆₀ monoadducts from polyadducts and unreacted C₆₀ from fulleropyrrolidine and hydroarylation example reaction mixtures. Six HPLC columns with regular reversed phase stationary phases were evaluated using varying proportions of acetonitrile in toluene as eluent; with C18 and C12 stationary phases with high surface area (450–400 m² g⁻¹) being the most efficient regarding separation efficiency and analysis time for all mixtures. The analytical method is effectively transferrable to a preparative scale to isolate the monoaddition products from complex fullerene reaction mixtures.

Isolation and purification of functionalized fullerenes from often complex reaction mixtures is challenging. Here, a simple and efficient HPLC method is presented.