19F and 13C GIAO-NMR chemical shifts for the identification of perfluoro-quinoline and -isoquinoline derivatives

Effects of Replacing Oxygenated Functionality with Fluorine on Lipophilicity

The replacement of oxygenated functionality (hydroxy and alkoxy) with a fluorine atom is a commonly used bioisosteric replacement in medicinal chemistry. In this paper, we use molecular matched-pair analysis to better understand the effects of this replacement on lipophilicity. It seems that the reduced log P of the oxygenated compound is normally dominant in determining the size of this difference. We observe that the presence of additional electron-donating groups on an aromatic ring generally increases the difference in lipophilicity between an oxygenated compound and its fluorinated analogue, while electron-withdrawing groups lead to smaller differences. Ortho-substituted compounds generally display a reduced difference in log P compared to para- and meta-substituted compounds, particularly if an ortho-substituent can form an intramolecular hydrogen bond. Hydrogen-bond acceptors remote to an aromatic ring containing fluorine/oxygen can also reduce the difference in log P between oxygen- and fluorine-substituted compounds.

Reaction of hydroxyl-quinoline with pentafluoropyridin

Reaction of pentafluoropyridine with 2 or 8-hydroxyl-quinoline under basic conditions in acetonitrile gives 4-oxy quinoline 2,3,5,6-tetrafluoropyridine derivatives in good yields. All the compounds were characterized using ¹H, ¹³C, ¹⁹F-NMR and MS spectroscopy.

Synthesis of 2-tetrafluoropyridyl-4,5-disubstituted 1,2,3-triazoles

Abstract

By cycloaddition reaction of sodium azide with chalcone in the presence of CuO as a catalyst in DMF a 1,2,3-triazole are prepared in reaction with pentafluoropyridine to give 2-(tetrafluoropyridin-4-yl)-1,2,3-triazole derivatives in good yields and high regioselectivity. The regioselectivity of the compounds are confirmed by ¹⁹F-NMR and other spectroscopy.

Graphical Abstract

Quantitative analysis of sitagliptin using the19F-NMR method: a universal technique for fluorinated compound detection

¹⁹F-NMR spectroscopy is employed to expand the application scope of NMR technology in quantitative analysis of pharmaceutical ingredients.

Computational19F NMR. 2. Organic compounds

DFT calculations allow to model and predict¹⁹F NMR chemical shift in a wide variety of organofluorine molecules.