Structure-activity relationship of thiopyrimidines as mGluR5 antagonists

5-Aryl-6-arylthio-2,2'-bipyridine and 6-Arylthio-2,5-diarylpyridine Fluorophores: Pot, Atom, Step Economic (PASE) Synthesis and Photophysical Studies

A PASE (pot, step, atom, economic) synthetic approach to 5-aryl-6-arylthio-2,2'-bipyridine and 6-arylthio-2,5-diarylpyridine ligands/fluorophores has been reported via S_NH in 6-aryl-5H-1,2,4-triazines/aza-Diels-Alder reaction sequence. In this article, the "1,2,4-triazine" methodology was successfully used for the synthesis of C6-thiophenol-substituted (2,2'-bi)pyridines as it is well known that thio-substituted (bi)pyridines and their aza-analogs are of wide practical interest. The photophysical properties of the obtained compounds are studied and compared with those reported earlier for 6-substituted 2,2'-bipyridines. The influence of the nature of substituents in the 6-arylthio(bi)pyridine core on the photophysical properties is discussed. It was observed that the new compounds exhibited promising photophysical properties and could be considered as potential push-pull fluorophores. In addition, they demonstrated greater Stokes shift values compared to the previously described 6-H, 6-arylamino and 6-pentafluoro-2,2'-bipyridines and higher fluorescence quantum yields values compare to pentafluorophenyl-substituted 2,2'-bipyridines. Depending on a nature of (bi)pyridine fluorophore LE (locally excited) and/or ICT (intramolecular charge transfer) state were prevailing in emission spectra.

Synthesis, crystal structure and cytotoxic activity of novel 5-methyl-4-thiopyrimidine derivatives

This article presents the synthesis of three new 4-thiopyrimidine derivatives obtained from ethyl 4-methyl-2-phenyl-6-sulfanylpyrimidine-5-carboxylate as the starting material, namely, ethyl 4-[(4-chlorobenzyl)sulfanyl]-6-methyl-2-phenylpyrimidine-5-carboxylate, C₂₁H₁₉ClN₂O₂S, (2), {4-[(4-chlorobenzyl)sulfanyl]-6-methyl-2-phenylpyrimidin-5-yl}methanol, C₁₉H₁₇ClN₂OS, (3), and 4-[(4-chlorobenzyl)sulfanyl]-5,6-dimethyl-2-phenylpyrimidine, C₁₉H₁₇ClN₂S, (4), which vary in the substituent at the 5-position of the pyrimidine ring. The compounds were characterized by ¹H NMR, ¹³C NMR, IR and mass spectroscopies, and also elemental analysis. The molecular structures were further studied by single-crystal X-ray diffraction. Compound (2) crystallizes in the space group P-1 with one molecule in the asymmetric unit, whereas compounds (3) and (4) crystallize in the space group P2₁/c with two and one molecule, respectively, in their asymmetric units. The conformation of each molecule is best defined by the dihedral angles formed between the pyrimidine ring and the planes of the two aryl substituents attached at the 2- and 4-positions. The only structural difference between the three compounds is the substituent at the 5-position of the pyrimidine ring, but they present significantly different features in the hydrogen-bond interactions. Compound (2) displays a one-dimensional chain formed by hydrogen bonds and the chains are further extended into a two-dimensional network. Molecules of (3) and (4) generate one-dimensional chains formed through intermolecular interactions. The study examines the cytotoxicity of compounds (3) and (4) against Human umbilical vein endothelial cells (HUVEC) and HeLa, K562 and CFPAC cancer cell lines. The presence of the hydroxymethyl and methyl groups in (3) and (4), respectively, offers an interesting new insight into the structures and behaviour of these derivatives. Compound (4) was found to be nontoxic against CFPAC and HUVEC; however, it shows weak activity against the HeLa and K563 cell lines. The presence of a hydroxy group in (3) significantly increases its cytotoxicity towards both, i.e. the cancer (HeLa, K562 and CFPAC) and normal (HUVEC) cell lines.

Synthesis and SAR of novel, non-MPEP chemotype mGluR5 NAMs identified by functional HTS

This Letter describes the discovery and SAR of three novel series of mGluR5 non-competitive antagonists/negative allosteric modulators (NAMs) not based on manipulation of an MPEP/MTEP chemotype identified by a functional HTS approach. This work demonstrates fundamentally new mGluR5 NAM chemotypes with submicromolar potencies, and further examples of a mode of pharmacology 'switch' to provide PAMs with a non-MPEP scaffold.

Discovery and SAR of novel mGluR5 non-competitive antagonists not based on an MPEP chemotype

This Letter describes the discovery and SAR of three novel series of mGluR5 non-competitive antagonists/negative allosteric modulators (NAMs) not based on manipulation of an MPEP/MTEP chemotype. This work demonstrates fundamentally new mGluR5 NAM chemotypes with submicromolar potencies, and the first example of a mode of pharmacology 'switch' to provide PAMs with a non-MPEP scaffold.

Synthesis and SAR of 2-aryl pyrido[2,3-d]pyrimidines as potent mGlu5 receptor antagonists

A novel series of potent 2-aryl pyrido[2,3-d]pyrimidine mGlu5 receptor antagonists are described. The synthesis and pharmacological activities of these analogs are discussed.

Discovery of heterobicyclic templates for novel metabotropic glutamate receptor subtype 5 antagonists

Investigation of a series of heterobicyclic compounds with essential pharmacophoric features of the metabotropic glutamate receptor 5 (mGluR5) antagonists MPEP and MTEP provided novel structural templates with sub-micromolar affinities at the mGluR5.

Rational design, synthesis, and structure–activity relationship of benzoxazolones: New potent mglu5 receptor antagonists based on the fenobam structure

A novel class of potent and stable mGlu5 receptor antagonists was developed by combining information from a high-throughput screening campaign with the structure of the known anxiolytic fenobam. Representative compounds from this class show favorable pharmacokinetic properties and are active in an in vivo model of anxiety.