Diaryl ether and diaryl thioether syntheses on solid supports via copper (I)-mediated coupling.
An efficient method to synthesize diaryl ethers and thioethers on solid supports is described. Starting from immobilized phenols or arylhalides, coupling with an access of aryliodides/arylbromides or phenolic/thiophenolic substrates in solution was successful in the presence of CuCl and Cs(2)CO(3) as base. Coupling conditions known from solution-phase syntheses of diaryl ethers have been effectively modified and adapted to solid-phase synthesis. Optimized conditions enabled the coupling of sterically hindered and/or electronically deactivated aryl moieties. After coupling, a newly developed diversity-generating linker based on cinnamic acid allowed the diaryl ethers to be cleaved from the resin either via saponification/transesterification or via ozonolysis. Latter offers the possibility of generating several additional compounds by simple variation of the cleavage conditions. The target substances were generally isolated in good to excellent yields and high purities.
Synthesis and degranulation-inhibiting activities of the proposed apteniols B, C, and G
The synthesis of compounds with the structures proposed for the oxyneolignan apteniols B, C, and G is described. The diphenyl ether skeletons of the proposed apteniols were formed via Ullmann ether synthesis. In particular, the spectral data for the synthesized apteniols B, C, and G did not agree with those previously reported for the isolated compounds. Furthermore, the synthesized proposed apteniol B did not show degranulation-inhibiting activity, while the prepared proposed apteniols C and G exhibited activities considerably weaker than that of the methyl ester of proposed apteniol A. Graphical Abstract The synthesis of proposed apteniols B, C, and G is described. The spectral data of the synthesized apteniols B, C, and G did not agree with those of isolated compounds.
Dating of Historical Manuscripts Using Spectrometric Methods: A Mini-Review
An overview is provided of spectrometric methods useful for age estimation of historical manuscripts (medieval ones in particular), in order to confirm their authenticity. Individual methods (infrared and Raman spectroscopy, mass spectrometry, atomic emission spectroscopy, X-ray spectroscopy, and electron scanning microscopy) are discussed and examples of their application described. The following general strategy can be recommended for dating and/or authenticating of historical manuscripts. First of all, the pigment analysis should be carried out using Raman spectroscopy (distinguishing the period and modern pigments), followed by PIXE ink analysis (solving the question of ink homogeneity). Finally, the radiocarbon dating of the writing support, potentially supplemented by the ink dating using scanning Auger microscopy should be performed.