Tetrahedron Letters最新文献

Organic photovoltaic (OPV) solar cells are a promising emerging technology for sustainable energy generation. In these cells, the absorbing layer consists of a repeated series of aromatic organic rings with a system of π delocalized electrons, a feature that allows these materials to absorb sunlight and facilitate electron transfer. In the present work, a new tetrameric molecule with high structural complexity, 4-phenyl-7-(5-(thiazol-2-yl) thien-2-yl)benzo[c][1,2,5]thiadiazole, was synthesized by a convergent pathway. The final step of the synthetic route was the Suzuki coupling of two new dimeric molecules, obtained from commercially available raw materials such as thiophene and o-phenylenediamine. The band gap of the final compound was found to be 2.5 eV using an optical methodology and 2.38 eV using an electrochemical methodology. The results suggest that this tetrameric molecule has potential for application in OPV cells.

Some new quinoline linked fused 1,2,3-triazole hybrids (5a-5o) were synthesized via Cu(I) catalyzed azide-alkyne cycloaddition followed by intramolecular CH arylation in one pot. Further, these derivatives were screened for their anti-breast cancer activity against MCF-7, MDA-MB-468 and MDA-MB-231 cell lines and results were compared with the 5-fluorouracil (5-FU). Out of all, compounds 5a, 5c, 5f, 5g and 5j displayed higher activity than the 5-FU against three cancer cell lines. Compound 5a was more effective in inhibiting both tyrosine kinase EGFR and HER2 enzymes than the Erlotinib and Lapatinib. Furthermore, compound 5j demonstrated greater potency than the Erlotinib against EGFR. Molecular docking studies revealed the important binding features of most potent compounds 5a, 5c, 5f, 5g and 5j with EGFR (PDB ID-4HJO) and HER2 (PDB ID-3RCD) and results were found to be supportive with corresponding IC₅₀ data. Finally, in silico pharmacokinetic studies revealed that compounds 5a, 5c, 5f, 5g and 5j followed Ghose, Egan, Muegge, Lipinski and Veber rules without any deviation.

A variety of bistricyclic aromatic enes (BAEs) and its derivatives have been prepared via the palladium-catalyzed Suzuki coupling/Heck cyclization tandem reaction in one pot. In the new proposal the expected products were obtained in exciting yields at nearly equimolar ratios of the substrates. It is very useful method for the synthesis of the fluorenylidene-based BAEs. Even the corresponding ladder-type conjugated polymer was also prepared by the tandem reaction.

Fast, atom-economical, phosphine-free, and eco-friendly microwave-irradiated reactions permitting the “green synthesis” of 5,6-disubstituted imidazo[2,1-b]thiadiazole derivatives using heterogeneous palladium catalyst in triethylammonium 2-(1,1-dioxido-3-oxobenzo[d]isothiazol-2(3H)-yl)acetate ([Et₃NH][Sac-CH₃CO₂]) ionic liquid via CH bond activation reaction of 6-substituted imidazo[2,1-b]thiadiazole derivatives, are reported. This method provides a straightforward route to a wide variety of substituted imidazo[2,1-b]thiadiazoles and has the advantages of reusability of the heterogeneous catalyst, simple methodology, high yields, and easy work-up.

The construction of a benzo-fused tetracyclic sulfonamide, followed by its low-valent titanium-based reduction and subsequent conversion to racemic crinane is reported. The synthesis of the tetracyclic sulfonamide features a sulfonyl templated, regio- and diastereoselective intramolecular Heck reaction, which installs an all-carbon quaternary centre. Thereafter, a low-valent titanium reduction removes the sulfonyl group, liberating a 3-aryloctahydroindole. A Pictet-Spengler reaction then generates the targeted ethano-bridged phenanthridine core structure of the crinan alkaloids.

In this study, we have successfully constructed two novel self-assembled composites, the ZnPx-ZnPAc (x = 1,2), which based on zinc porphyrin derivatives, and applied them to the development of dye-sensitized solar cells. The upper dye of these self-assembly’s features zinc porphyrin (ZnPx) as the core unit, while two different electron donors, methoxy (P1) and trifluoromethyl (P2), are introduced to enhance their photovoltaic properties. Photoelectrochemical studies showed that the power conversion efficiency of ZnP1-ZnPAc was superior to that of ZnP2-ZnPAc because ZnP1-ZnPAc had larger J_sc and V_oc, which could be attributed to the stronger electron-donating ability of methoxy than trifluoromethyl. To further validate the photoelectrochemical results, we also characterized the assembly mode by spectroscopy, theoretical calculations and electrochemical impedance spectroscopy. And the measurements were consistent with the conclusions.

A macrocyclic peptide, okeaniazole A (1), was isolated from the Okinawan marine cyanobacterium, Okeania hirsuta. The planar structure was elucidated by the analyses of MS and NMR spectra. The absolute configuration of the amino acid residues was determined by a combination of ozonolysis, hydrolysis, and Marfey’s analysis. Okeaniazole A (1) and a related cyclic heptapeptide dolastatin 3 (2) exhibited antileishmanial activity, with IC₅₀ values of 12.1 and 12.5 µM, respectively. These two compounds did not show any cytotoxicity toward L1210 mouse leukemia cells at concentrations of 100 µM.

Ester tub[4]arene, a conformationally adaptive macrocycle with interconvertible cavities, has been synthesized and characterized. Its conformational complexity was analyzed, and its binding ability to organic cations was studied by ¹H NMR spectroscopy and UV–vis spectroscopy. The conformational conversion of the host can be achieved by binding a suitable guest. The binding performance of such adaptable receptors may have significant implications for the molecular recognition processes occurring in natural settings.

An efficient synthesis of thieno[2,3-b]quinoxalines by thiolative cyclization of 2-chloro-3-(phenylethynyl)quinoxalines using primary thioamides as sulfur sources has been proposed. The reactions provided moderate to good yields under mild conditions.