Published: January 30th, 2019
A novel and straightforward variation of the shake-flask method was developed for accurate lipophilicity measurement of fluorinated compounds by 19F NMR spectroscopy.
Fluorination has become an effective tool to optimize physicochemical properties of bioactive compounds. One of the applications of fluorine introduction is to modulate the lipophilicity of the compound. In our group, we are interested in the study of the impact of fluorination on lipophilicity of aliphatic fluorohydrins and fluorinated carbohydrates. These are not UV-active, resulting in a challenging lipophilicity determination. Here, we present a straightforward method for the measurement of lipophilicity of fluorinated compounds by 19F NMR spectroscopy. This method requires no UV-activity. Accurate solute mass, solvent and aliquot volume are also not required to be measured. Using this method, we measured the lipophilicities of a large number of fluorinated alkanols and carbohydrates.
Lipophilicity is a key physicochemical parameter of drug molecules which influences the properties of drug candidates in many aspects, including drug solubility, bioavailability, and toxicity1. Lipophilicity is measured as the logarithm (logP) of the ratio of compound concentrations after partitioning between n-octanol and water. Optimal lipophilicity ranges have been proposed based on statistical data of orally administered drugs, of which the Lipinski's "rule of 5'' is the most famous example2,3. Indeed, controlling lipophilicity has shown to be essential for ....
Two sets of data as control experiments are shown in Figure 221. Using 2,2,2-trifluoroethanol as reference compound, logP values were obtained for 2-fluoroethanol and 3,3,3,2,2-pentafluoropropanol as -0.75 and +1.20, respectively (Figure 2A). Subsequently, the lipophilicity of 2-fluoroethanol was determined again but with 3,3,3,2,2-pentafluoropropanol as the reference (using its previous experimen.......
The protocol described in the paper is a straightforward method for logP measurement of fluorinated compounds. This method is applicable to fluorinated compounds with a logP value from -3 to 3. For more hydrophilic (logP < -3) or lipophilic compounds (logP > 3), this method can still be used but will require much longer NMR experiment time as extended number of transients are needed to obtain a good signal-to-noise ratio. Hence, this is a limitation of the method. There is no r.......
This research is funded as part of EPSRC grants EP/K016938/1 and EP/P019943/1 (ZW, HRF) and of an EPSRC/AstraZeneca CASE conversion award (BFJ). The University of Southampton is thanked for additional support. The EPSRC is further thanked for a core capability grant EP/K039466/1.....
|NMR (400 MHz) with Bruker 5 mm SEF probe
|NMR (400 MHz) with Bruker 5 mm SMART probe
|DrySyn Snowstorm reactor
|ACD/NMR processor software
|ACD/NMR processor academic edition or ACD/Spectrus processor 2015
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