Trimethyl-3-meth­oxy-4-oxo-5-triphenyl­phospho­ranyl­idene­cyclo­pent-1-ene-1,2,3-tricarboxyl­ate

The title compound, C30H27O8P (2), was formed as one of two products {(1) [Krawczyk et al. (2010 ▶). Acta Cryst. E66 (cv2752)] and (2)} in the reaction of dimethyl acetyl­enedicarboxyl­ate with triphenyl­phosphine. The mol­ecule of (2) consists of a five-membered carbocyclic ring. The P atom is a part of a triphenylphosphoranylidene substituent. In contrast to (1), the five-membered ring of (2) is planar, the r.m.s. deviation being only 0.009 (2) Å

Tetra­methyl 1,1,2-triphenyl-2H-1λ5-phosphole-2,3,4,5-tetra­carboxyl­ate

The title compound, C30H27O8P (1), was formed as one of two products {(1) and (2) [Krawczyk et al. (2010 ▶). Acta Cryst. E66 (cv2753)]} in the reaction of dimethyl acetyl­enedicarboxyl­ate with triphenyl­phosphine. The mol­ecule of (1) consists of a five-membered ring, in which the P atom is incorporated. One of the phenyl groups of the triphenyl­phosphine migrated to a vicinal C atom during the reaction. The five-membered ring of (1) is corrugated [r.m.s. deviation = 0.0719 (8) Å], whereas that in compound (2) is planar, the r.m.s. deviation being only 0.009 (2) Å

“Clicking“ fragment leads to novel dual-binding cholinesterase inhibitors

Cholinesterase inhibitors are potent therapeutics in the treatment of Alzheimer's disease. Among them, dual binding ligands have recently gained a lot of attention. We discovered novel dual-binding cholinesterase inhibitors, using “clickable” fragments, which bind to either catalytic active site (CAS) or peripheral anionic site (PAS) of the enzyme. Copper(I)-catalyzed azide-alkyne cycloaddition allowed to effectively synthesize a series of final heterodimers, and modeling and kinetic studies confirmed their ability to bind to both CAS and PAS. A potent acetylcholinesterase inhibitor with IC50 = 18 nM (compound 23g) was discovered. A target-guided approach to link fragments by the enzyme itself was tested using butyrylcholinesterase

Flow Photochemistry as a Tool for the Total Synthesis of (+)-Epigalcatin

The first total synthesis of (+)-epigalcatin was completed in a highly stereoselective manner starting from piperonal, 3,4-dimethylbenzaldehyde, and diethyl succinate. l-Prolinol was used as a chiral auxiliary. The crucial step in this procedure involves the construction of the cyclolignan framework by continuous-flow photocyclization of a chiral atropisomeric 1,2-bisbenzylidenesuccinate amide ester

The enantioselective synthesis of (S)-(+)-mianserin and (S)-(+)-epinastine

A simple enantioselective synthetic procedure for the preparation of mianserin and epinastine in optically pure form is described. The key step in the synthetic pathway is the asymmetric reduction of the cyclic imine using asymmetric transfer hydrogenation conditions

Antioxidant Activity of Sulfate Metabolites of Chlorogenic Acid

This study aimed to determine the antioxidant properties of the sulfate monoesters of ferulic, caffeic, dihydroferulic and dihydrocaffeic acids, the main metabolites of chlorogenic acids. These compounds are not commercially available, so they were synthesized in the laboratory. The LC-MS/MS analysis allowed for the full characterization of these derivatives, which has made them reliable standards for further research. Purified metabolites including ferulic acid-4-O-sulfate, caffeic acid-4-O-sulfate and caffeic acid-3-O-sulfate, dihydrocaffeic acid-4-O-sulfate and caffeic acid-3-O-sulfate were examined for their antioxidant capacities and compared to their precursor compounds using Folin–Ciocalteu, CUPRAC (cupric ion—reducing) and DPPH• (2,2-diphenyl-1-picrylhydrazyl) methods. This study shows that hydrogenation of caffeic and ferulic acids into dihydrocaffeic and dihydroferulic acids has a positive influence on their reducing properties. Moreover, all synthesized sulfate monoesters exhibited very weak antioxidant properties compared to precursor compounds. The presented results show that the transformation of phenolic acids via sulfation leads to the inhibition of antioxidant properties due to the blockage of hydroxyl groups

Antioxidant Activity of Sulfate Metabolites of Chlorogenic Acid

This study aimed to determine the antioxidant properties of the sulfate monoesters of ferulic, caffeic, dihydroferulic and dihydrocaffeic acids, the main metabolites of chlorogenic acids. These compounds are not commercially available, so they were synthesized in the laboratory. The LC-MS/MS analysis allowed for the full characterization of these derivatives, which has made them reliable standards for further research. Purified metabolites including ferulic acid-4-O-sulfate, caffeic acid-4-O-sulfate and caffeic acid-3-O-sulfate, dihydrocaffeic acid-4-O-sulfate and caffeic acid-3-O-sulfate were examined for their antioxidant capacities and compared to their precursor compounds using Folin–Ciocalteu, CUPRAC (cupric ion—reducing) and DPPH• (2,2-diphenyl-1-picrylhydrazyl) methods. This study shows that hydrogenation of caffeic and ferulic acids into dihydrocaffeic and dihydroferulic acids has a positive influence on their reducing properties. Moreover, all synthesized sulfate monoesters exhibited very weak antioxidant properties compared to precursor compounds. The presented results show that the transformation of phenolic acids via sulfation leads to the inhibition of antioxidant properties due to the blockage of hydroxyl groups

3-(2-Acetamidoethyl)-1H-indol-5-yl 4-nitrophenyl carbonate

In the title molecule, C19H17N3O6, the indole ring system is essentially planar (r.m.s. deviation = 0.009 Å) and forms a dihedral angle of 31.96 (9)° with the nitro-substituted benzene ring. In the crystal, molecules are linked by pairs of N—H...O hydrogen bonds, forming inversion dimers which are connected by further N—H...O hydrogen bonds into a two-dimensional network parallel to (102)

Some mechanistic aspects regarding the Suzuki–Miyaura reaction between selected ortho-substituted phenylboronic acids and 3,4,5-tribromo-2,6-dimethylpyridine

Background: Atropisomers are very interesting stereoisomers having axial chirality resulting from restricted rotation around single bonds and are found in various classes of compounds. ortho-Substituted arylpyridines are an important group of them. A regio- and atropselective Suzuki–Miyaura cross-coupling reaction on 3,4,5-tribromo-2,6-dimethylpyridine was studied.Results: Reactions with various amounts of ortho-substituted phenylboronic acids with 3,4,5-tribromo-2,6-dimethylpyridine gave a series of mono- di- and triarylpyridine derivatives which allowed to draw conclusions about the order of substitution. Also, the observed selectivity in the case of ortho-methoxyphenylboronic acid suggested an additional metal O-chelation effect in the transition state, apparently not present in the ortho-chloro analogues. The rotational barrier in selected atropisomers was determined on the basis of HT NMR and thermal epimerisation experiments. The structure of most presented atropisomeric derivatives of 2,6-dimethylpyridine was confirmed by single-crystal X-ray analysis. Racemic chiral, differently substituted atropisomers were also examined by 1H NMR spectroscopy in the presence of a chiral solvating agent.Conclusion: This regio- and atropselectivity may be generally applicable to other arylpyridine systems. A regio- and atropselective Suzuki–Miyaura cross-coupling process has been observed, giving an efficient access to a class of atropisomeric compounds. An opposite selectivity using a differently ortho-substituted phenylbornic acid was observed