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Abstract: The combination of (p-methoxyphenyl)imine, a bromonitroalkane, and zinc in the presence of catalytic indium allows straightforward access to β-nitroamine derivatives. The use of chiral sugar-derived imines furnished the corresponding β-nitroamines in high yields and stereoselectivities, from which the corresponding 1,2-diamines were easily obtained. The synthetic utility of the sugar-derived 1,2-diamines in the preparation of iminosugars was illustrated in a concise synthesis of 6-amino-1,6-dideoxynojirimycin. [Copyright &y& Elsevier]

Abstract: The Diels–Alder reaction of (E)-2-styrylchromones with a pyrimidine ortho-quinodimethane is reported for the first time. These cycloaddition reactions afford mixtures of two regioisomeric tetrahydroquinazoline-substituted chromones in moderate to excellent global yields. Irrespective of the substituents on the 2-styrylchromones, the 2-(7-aryl-4-methoxy-2-methyl-5,6,7,8-tetrahydroquinazolin-6-yl)chromone derivatives are always the major isomers. [Copyright &y& Elsevier]

Abstract: An efficient synthetic method for the preparation of (E)- and (Z)-3(5)-(2-hydroxyphenyl)-4-styrylpyrazoles has been developed. The reaction of (E)- and (Z)-3-styrylchromones with hydrazine hydrate afforded the corresponding (E)- and (Z)-4-styrylpyrazoles, respectively, saved 4′-nitro-derivatives where both (E)- and (Z)-4′-nitro-3-styrylchromones afforded (E)-3(5)-(2-hydroxyphenyl)-4-(4-nitrostyryl)pyrazoles. The reaction mechanism for these transformations was discussed and the stereochemistry of all products was assigned by NMR experiments. [Copyright &y& Elsevier]

A one-pot synthesis of novel 2-(2-hydroxyaryl)quinolines have been developed from the intramolecular reductive coupling reactions of 2′-hydroxy-2-nitrochalcones, induced by stannous chloride in acidic medium (HCl/AcOH). In some cases these transformations can be performed with ammonium formate/Pd–C in methanol. [Copyright &y& Elsevier]

Abstract: A new synthesis of a tetrahedral tecton, tetrakis(4-methoxyphenyl)methane, is reported. This compound exhibits a strong fluorescence around 340nm at room temperature, both in solution and in the solid state. Upon crystallization, another luminescence band can be observed around 500nm, attributed to phosphorescence. A study of the single-crystal structure of the compound provided a rationalization of this crystallization induced phosphorescence. The crystal of tetrakis(4-methoxyphenyl)methane belongs to the tetragonal space group P 21 c, and the structural analysis revealed a close packing of the molecules, with no void space and no solvent molecules in the crystal. The molecules are held together in a columnar array via multiple C–H⋯π hydrogen bonds. The hydrogen bonds between the molecules impede the torsional vibrations of the aromatic rings, preventing thermal relaxation from the triplet state, and hence promoting phosphorescence at room temperature. [Copyright &y& Elsevier]

Abstract: The present study reports the electrochemical behavior of several phenolic and catecholic-substituted 2,3-diarylxanthones on a glassy carbon electrode, challenged by cyclic voltammetry at different pH values (4.0, 7.4, and 11.0). Higher pH values required lower anodic and cathodic peak voltages. The oxidation of catecholic groups occurred at lower peak potentials in a reversible and pH dependent manner. Anodic peak potentials appeared at higher pH values and were attributed to the electrochemically irreversible oxidation of the phenolic groups. The number and position of hydroxyl substituents were the determinants for the electrochemical behavior and found to correlate with the scavenging activity for reactive oxygen (ROS) and nitrogen species (RNS). A xanthone with two catechol units presented the lowest anodic potential voltage (E pa =0.15V) and proved to be the most effective ROS and RNS scavenger. [Copyright &y& Elsevier]

3,4-Dihydropyrimidinones were synthesized by a multicomponent condensation of an aldehyde, a β-keto ester, and urea, in acetonitrile and ethanol using Keggin and Dawson type polyoxometalates as catalysts. Keggin heteropolyacid, H 4 SiMO 12 O 40 , is more efficient compared to Keggin and Dawson salts and to the Biginelli classical reaction conditions. It leads to good yields and short reaction times. Theoretical calculations let us to confirm the reaction mechanism. [ABSTRACT FROM AUTHOR]

The reactivity of porphyrinyl and corrolyl nitrones towards dipolarophiles bearing electron-withdrawing groups was studied and it was found that the two nitrones behave differently in 1,3-dipolar cycloaddition reactions. While porphyrinyl nitrone reacts with dimethyl fumarate, dimethyl acetylenedicarboxylate and ethyl propiolate to afford the expected isoxazolidine and isoxazoline cycloadducts, the corrolyl nitrone reacts with dimethyl fumarate to provide an isoxazolidine-substituted corrole but with dimethyl acetylenedicarboxylate it gives amide derivatives. [ABSTRACT FROM AUTHOR]

A two-step procedure transformation starting from the reaction of ortho -phenylenediamines on 2-acetylbutyrolactone 1 yielded ( Z )-3-(1-aminoethylidene)butyrolactones 2 , which were treated with either N , N -dimethylformamide dimethyl acetal, triphosgene, or carbon disulfide under different reaction conditions to produce a new series of benzimidazole–, benzimidazolone–, or benzimidazole-2-thione–butyrolactone dyads 3 – 5 , respectively. The structures of compounds 2 – 5 were established by NMR and mass spectrometry. The isolation of important reaction intermediates as single-crystals allowed the determination of the ( Z )-configuration in the resulting conjugate heterocyclic systems 3 – 5 by X-ray diffraction studies. [ABSTRACT FROM AUTHOR]

The development of an efficient synthetic method toward substituted 1,2-dihydropyridines from cinnamylideneacetophenones is reported. The key intermediates N -sulfonylazatrienes were synthesized through a TiCl 4 -mediated direct condensation of primary sulfonamides with the substituted ( E , E )-cinnamylideneacetophenones. The 6π-electrocyclization of these intermediates, catalyzed by a Lewis acid, selectively afforded the desired products in good yields. [ABSTRACT FROM AUTHOR]

Abstract: An efficient two step synthetic methodology of new 5(4)-aryl-4(5)-[3(5)-(2-hydroxyphenyl)-1H-pyrazol-5(3)-yl]-1H-1,2,3-triazole dyads was established. The reaction of (E)-2-styryl-4H-chromen-4-ones, used as building blocks, with sodium azide, gave 4(5)-aryl-5(4)-(chromon-2-yl)-1H-1,2,3-triazoles bearing either electron-donating or electron-withdrawing substituents in their styryl moiety which upon reaction with hydrazine hydrate afforded the expected pyrazoles in moderate to very good yields. [Copyright &y& Elsevier]

Abstract: New flavonoid–porphyrin conjugates were synthesized using the cross-coupling Buchwald–Hartwig amination for the coupling of flavonoid and porphyrin moieties. A unique di-substituted flavone–porphyrin conjugate was also synthesized under similar reaction conditions for the first time. All the conjugates were fully characterized by NMR spectroscopy. The photophysical properties namely fluorescence and singlet oxygen production were evaluated considering their use for photodynamic therapy applications. [Copyright &y& Elsevier]

Abstract: We report the synthesis of novel 2H,8H-pyrano[2,3-f]chromene-2,8-dione based scaffolds by the reaction of 8-formyl-7-hydroxy-4-methylcoumarin with various active methylene compounds. A mechanism of a tandem Knoevenagel condensation and cyclisation reaction is proposed. The structure of all compounds was established on the basis of 1H and 13C NMR data, high resolution mass spectrometry and elemental analysis. [Copyright &y& Elsevier]

Abstract: The catalytic insertion of ethyl diazoacetate into a porphyrin derivative bearing an NH2 substituent, in the presence of a Rh-based catalyst, was investigated. The X-ray analysis of one of the isolated products reveals the formation of a chiral supramolecular system. [Copyright &y& Elsevier]

Abstract: Two new anthocyanin-derived compounds corresponding to the ethylpyranomalvidin-3-glucoside and the pyranomalvidin-3-glucoside dimer linked through a methyl-methine bridge were synthesized for the first time and their structure characterized by LC-DAD/MS and NMR spectroscopy. The latter was obtained in a hydroalcoholic model solution through the reaction of the carboxypyranomalvidin-3-glucoside with ethylpyranomalvidin-3-glucoside and displays a blue/green color in solution. [Copyright &y& Elsevier]

Abstract: The biomimetic oxidation of caffeine with hydrogen peroxide using metalloporphyrins as catalysts, which are known to be good biomimetic models of cytochrome P450 enzymes, is investigated. The two manganese porphyrins tested, chloro[5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrinato]manganese(III), [Mn(TDCPP)Cl], and chloro [5,10,15,20-tetrakis(pentafluorophenyl)porphyrinato]manganese(III), [Mn(TPFPP)Cl], afford high conversions of caffeine for all substrate/catalyst molar ratios. Selectivity was found to be dependent on the catalyst employed, and a new spiro racemic compound is described and fully characterized in the solid state from X-ray diffraction studies. [Copyright &y& Elsevier]

Abstract: 5,10,15-Tris(pentafluorophenyl)corrole slowly undergoes oligomerization when left in solution at room temperature, under air and ambient light. This transformation was studied in different solvents (chloroform, dichloromethane, and toluene) and the main resulting products were identified as the 3,3′-corrole dimer 2a and the 3,3′,17′,3′′-corrole trimer 3a. [Copyright &y& Elsevier]

Abstract: Gallium(III)(pyridine) complex of 5,10,15-tris(pentafluorophenyl)corrole-3-carbaldehyde was used as a precursor of an azomethine ylide, which was trapped in 1,3-dipolar cycloaddition reactions with quinones. Besides the expected dehydrogenated 1,3-dipolar cycloadducts, novel quinone-fused corrole derivatives were also obtained in moderate yields. [Copyright &y& Elsevier]

Abstract: Three corrole dimers were obtained by heating a 1,2,4-trichlorobenzene solution of 5,10,15-tris(pentafluorophenyl)corrole at 200°C. The corrole units are linked by the β,β′-positions. In one of these dimers the corrole units are linked by the 2,2′,18,18′ carbons, giving rise to an eight-membered ring. [Copyright &y& Elsevier]

Abstract: Sapphyrins participate in Diels–Alder reactions with pentacene affording novel barrelene-fused sapphyrins. The new compounds were synthesized using traditional heating and microwave irradiation conditions. The experiments carried out under microwave irradiation proved cleaner, affording only the monoadduct and in higher yields. [Copyright &y& Elsevier]

Abstract: Porphyrinic pyridinium ylides react with 1,4-benzoquinone and 1,4-naphthoquinone to afford novel meso-substituted indolizine porphyrins. [Copyright &y& Elsevier]

• First Pd-catalyzed one-pot synthesis of azaindoles from halogen-free aminopyridines. • Reactivity of aminopyridines under Pd-catalyzed reaction conditions. • Atom-economical and regioselective synthesis of azaindoles. • 4-aza and 6-azaindoles in up to 96% overall yield. Aminopyridines are key building blocks for the synthesis of bioactive N -heterocyclic compounds such as azaindoles and imidazopyridines. However, the functionalization of aminopyridines is challenging, due to their electronic properties and coordination with metals. Herein we describe a reactivity study of aminopyridines under palladium-catalyzed reaction conditions. Several aminopyridines underwent a one-pot Pd-catalyzed C–N cross coupling reaction/C–H functionalization sequence affording azaindoles. The role of additives, ligands, and bases was investigated. This work consists of a platform for future studies on aminopyridines involving metal-catalyzed reactions and represents the first report on the direct conversion of non-halogenated aminopyridines into azaindoles via Pd-catalyzed C–H functionalization reactions. [ABSTRACT FROM AUTHOR]

Abstract: Novel π-extended porphyrins were obtained from the Diels–Alder reaction of meso-tetraarylporphyrins with a pyrazine o-quinodimethane derivative. [Copyright &y& Elsevier]

A new polyphenolic compound, the structure of which corresponds to a pyranomalvidin-3-glucoside linked to a (+)-catechin unit through a vinyl linkage, has been characterized by UV–vis, MS and NMR spectroscopy. This compound was obtained in an aqueous alcoholic solution from the reaction between a malvidin-3-glucoside–pyruvic acid derivative and (+)-catechin in the presence of acetaldehyde. [Copyright &y& Elsevier]

Formyl derivatives of protoporphyrin-IX dimethyl ester metal complexes were obtained via hydroformylation reactions, catalysed by rhodium–triphenylphosphine complexes. The regioselectivity of the reaction is remarkably dependent on the metal centre of the porphyrin, yielding 100% of the branched aldehyde with zinc(II) complexes and 75% with the nickel(II). The NMR characterisation of the new compounds was carried out after their derivatisation into acetals. [Copyright &y& Elsevier]