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1.
J Med Chem ; 65(12): 8511-8524, 2022 06 23.
Article in English | MEDLINE | ID: mdl-35678759

ABSTRACT

Systematically studying the lipophilicity of phosphorus compounds is of great importance for many chemical and biological fields and particularly for medicinal chemistry. Here, we report on the study of trends in the lipophilicity of a wide set of phosphorus compounds relevant to drug design including phosphates, thiophosphates, phosphonates, thiophosphonates, bis-phosphonates, and phosphine chalcogenides. This was enabled by the development of a straightforward log P determination method for phosphorus compounds based on 31P-NMR spectroscopy. The log P values measured ranged between -3.2 and 3.6, and the trends observed were interpreted using a DFT study of the dipole moments and by H-bond basicity (pKHB) measurements of selected compounds. Clear signal separation in 31P-NMR spectroscopy grants the method high tolerability to impurities. Moreover, the wide range of chemical shifts for the phosphorus nucleus (250 to -250 ppm) enables a direct simultaneous log P determination of phosphorus compound mixtures in a single shake-flask experiment and 31P-NMR analysis.


Subject(s)
Organophosphonates , Phosphorus Compounds , Magnetic Resonance Spectroscopy/methods , Phosphorus/chemistry
2.
J Med Chem ; 64(8): 4516-4531, 2021 04 22.
Article in English | MEDLINE | ID: mdl-33844540

ABSTRACT

Modulation of the H-bond basicity (pKHB) of various functional groups (FGs) by attaching fluorine functions and its impact on lipophilicity and bioisosterism considerations are described. In general, H/F replacement at the α-position to H-bond acceptors leads to a decrease of the pKHB value, resulting, in many cases, in a dramatic increase in the compounds' lipophilicity (log Po/w). In the case of α-CF2H, we found that these properties may also be affected by intramolecular H-bonds between CF2H and the FG. A computational study of ketone and sulfone series revealed that α-fluorination can significantly affect overall polarity, charge distribution, and conformational preference. The unique case of α-di- and trifluoromethyl ketones, which exist in octanol/water phases as ketone, hemiketal, and gem-diol forms, in equilibrium, prevents direct log Po/w determination by conventional methods, and therefore, the specific log Po/w values of these species were determined directly, for the first time, using Linclau's 19F NMR-based method.


Subject(s)
Fluorine/chemistry , Ketones/chemistry , Density Functional Theory , Halogenation , Hydrogen Bonding , Hydrophobic and Hydrophilic Interactions , Isomerism , Ketones/chemical synthesis , Kinetics , Magnetic Resonance Spectroscopy , Pyridines/chemical synthesis , Pyridines/chemistry , Sulfones/chemical synthesis , Sulfones/chemistry
3.
J Med Chem ; 62(11): 5628-5637, 2019 06 13.
Article in English | MEDLINE | ID: mdl-31091098

ABSTRACT

The effects of the CF2H moiety on H-bond (HB) acidity and lipophilicity of various compounds, when attached directly to an aromatic ring or to other functions like alkyls, ethers/thioethers, or electron-withdrawing groups, are discussed. It was found that the CF2H group acts as a HB donor with a strong dependence on the attached functional group ( A = 0.035-0.165). Regarding lipophilicity, the CF2H group may act as a more lipophilic bioisostere of OH but as a similar or less lipophilic bioisostere of SH and CH3, respectively, when attached to Ar or alkyl. In addition, the lipophilicity of ethers, sulfoxides, and sulfones is dramatically increased upon CH3/CF2H exchange at the α position. Interestingly, this exchange significantly affects not only the polarity and the volume of the solutes but also their HB-accepting ability, the main factors influencing log Poct. Accordingly, this study may be helpful in the rational design of drugs containing this moiety.


Subject(s)
Fluorocarbons/chemistry , Hydrophobic and Hydrophilic Interactions , Hydrogen Bonding , Models, Molecular , Molecular Conformation
4.
J Med Chem ; 60(2): 797-804, 2017 01 26.
Article in English | MEDLINE | ID: mdl-28051859

ABSTRACT

There is a growing interest in organic compounds containing the difluoromethyl group, as it is considered a lipophilic hydrogen bond donor that may act as a bioisostere of hydroxyl, thiol, or amine groups. A series of difluoromethyl anisoles and thioanisoles was prepared and their druglike properties, hydrogen bonding, and lipophilicity were studied. The hydrogen bond acidity parameters A (0.085-0.126) were determined using Abraham's solute 1H NMR analysis. It was found that the difluoromethyl group acts as a hydrogen bond donor on a scale similar to that of thiophenol, aniline, and amine groups but not as that of hydroxyl. Although difluoromethyl is considered a lipophilicity enhancing group, the range of the experimental Δlog P(water-octanol) values (log P(XCF2H) - log P(XCH3)) spanned from -0.1 to +0.4. For both parameters, a linear correlation was found between the measured values and Hammett σ constants. These results may aid in the rational design of drugs containing the difluoromethyl moiety.


Subject(s)
Hydrocarbons, Fluorinated/chemistry , Anisoles/chemical synthesis , Anisoles/chemistry , Hydrocarbons, Fluorinated/chemical synthesis , Hydrogen Bonding , Hydrophobic and Hydrophilic Interactions , Lewis Acids/chemical synthesis , Lewis Acids/chemistry , Proton Magnetic Resonance Spectroscopy , Sulfides/chemical synthesis , Sulfides/chemistry
5.
J Org Chem ; 81(19): 9180-9187, 2016 10 07.
Article in English | MEDLINE | ID: mdl-27607245

ABSTRACT

A practical, convenient, and general method for the difluoromethylation of tertiary amines, using diethyl bromodifluoromethylphosphonate and fluoride, is described. This commercially available phosphonate smoothly reacts with a fluoride ion to liberate a difluorocarbene intermediate that in the presence of a proton source and a tertiary amine generates the corresponding α-difluoromethylammonium compound in good to excellent yields. Despite the involvement of a difluorocarbene intermediate, this difluoromethylation occurs almost exclusively on the nitrogen atom with diverse molecular structures, including drugs, surfactants, chiral phase transfer catalysts, polymers, ionic liquids, and other fine chemicals. A preliminary assessment of the effects that an α-difluoromethyl groupT has on hydrogen bonding and logP of quaternary ammonium salts is also described.

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