RESUMEN
Functional group (FG) is one of the cornerstone concepts in organic chemistry and related areas. The wide spread of bioisosterism ideas in medicinal chemistry and beyond caused a striking rise in demand for novel FGs with a defined impact on the developed compound properties. In this work, the evaluation of the 3,3-difluorooxetane unit (3,3-diFox) as a functional group for bioisosteric replacements is disclosed. A comprehensive experimental study (including multigram building block synthesis, quantification of steric and electronic properties, measurements of pKa, LogP, chemical stability, and biological evaluation of the 3,3-diFox-derived bioisostere of a drug candidate) revealed a prominent behavior of the 3,3-diFox fragment as a versatile substituent for early drug discovery programs.
RESUMEN
A new one-pot approach for the synthesis of the Zn2+-sensitive probes 2-azahetaryl-2-(oxoindolin-2-ylidene)acetonitriles 3a-c and 4 is described. The method includes the in situ formation of imidoylchloride and its further condensation with azahetarylacetonitrile 1. The structure of the obtained compounds is studied using 1H nuclear magnetic resonance (NMR), 13C NMR, infrared (IR), high-resolution mass spectrometry (HRMS), and UV-Vis spectroscopy techniques. Two model ligands both exhibiting the highest extinction coefficient and the best solubility in a Tris buffer pH 7.2/dimethyl sulfoxide (DMSO) solution, namely 5-methyl-benzothiazole derivative 3b and benzoxazole derivative 4, are thoroughly studied as colorimetric probes for Zn2+. The probe 3b has the highest sensitivity to Zn2+, showing a limit of ion detection (LOD) calculated by the 3S criterion of 0.43 µM and selectivity upon masking Cu2+ ions with Na2S2O3. The composition of the complexes in the solution was determined by the limited logarithm method. The stability constant (lgâ¯K) values of 3b-Zn of 10.27 ± 0.02 and 4-Zn of 12.5 ± 0.2 indicate the formation of complexes of average stability.