An Expeditious and Efficient Synthesis of Highly Functionalized [1,6]-Naphthyridines under Catalyst-Free Conditions in Aqueous Medium

This is the first report of an innovative, one-pot, catalyst-free, pseudo-five-component synthesis of 1,2-dihydro[1,6]naphthyridines from methyl ketones, amines, and malononitrile in ecofriendly solvent water. The protocol avoids the use of expensive catalysts, toxic organic solvents and anhydrous condition. The approach to naphthyridines presented herein offers for the first time an unprecedented coupling which leads to the construction of both the nitrogen containing rings during the synthesis without starting from any nitrogen-containing heterocycle moiety

An Expeditious and Efficient Synthesis of Highly Functionalized [1,6]-Naphthyridines under Catalyst-Free Conditions in Aqueous Medium

This is the first report of an innovative, one-pot, catalyst-free, pseudo-five-component synthesis of 1,2-dihydro[1,6]naphthyridines from methyl ketones, amines, and malononitrile in ecofriendly solvent water. The protocol avoids the use of expensive catalysts, toxic organic solvents and anhydrous condition. The approach to naphthyridines presented herein offers for the first time an unprecedented coupling which leads to the construction of both the nitrogen containing rings during the synthesis without starting from any nitrogen-containing heterocycle moiety

Chemically Induced Cyclometalation of 2-(Arylazo)phenols. Synthesis, Characterization, and Redox Properties of a Family of Organoosmium Complexes

Reaction of 2-(arylazo)phenols (H2ap-R; R = OCH3, CH3, H, Cl, and NO2) with [Os(PPh3)2(CO)2(HCOO)2] affords a family of organometallic complexes of osmium(II) of type [Os(PPh3)2(CO)(ap-R)] where the 2-(arylazo)phenolate ligand is coordinated to the metal center as a tridentate C,N,O-donor. Structure of the [Os(PPh3)2(CO)(ap-H)] complex has been determined by X-ray crystallography. All the [Os(PPh3)2(CO)(ap-R)] complexes are diamagnetic and show characteristic 1H NMR signals and intense MLCT transitions in the visible region. They also show emission in the visible region at ambient temperature. Cyclic voltammetry on the [Os(PPh3)2(CO)(ap-R)] complexes shows a reversible Os(II)−Os(III) oxidation within 0.39−0.73 V vs SCE, followed by a reversible Os(III)−Os(IV) oxidation within 1.06−1.61 V vs SCE. Coulometric oxidation of the [Os(PPh3)2(CO)(ap-R)] complexes generates the [OsIII(PPh3)2(CO)(ap-R)]+ complexes, which have been isolated as the hexafluorophosphate salts. The [OsIII(PPh3)2(CO)(ap-R)]PF6 complexes are one-electron paramagnetic and show axial ESR spectra. In solution they behave as 1:1 electrolytes and show intense LMCT transitions in the visible region. The [OsIII(PPh3)2(CO)(ap-R)]PF6 complexes have been observed to serve as mild one-electron oxidants in a nonaqueous medium

Stabilization of Organosilanetriols in Amine Matrices: Trapping Intermediates between RSi(OH)₃ and (RSiO₃)^3- Anions^§

Unless kinetically stabilized, hydroxides of silicon are unstable and readily self-condense through elimination of water molecules to yield Si−O−Si siloxane linkages. The condensation reaction is known to be very facile in the presence of acids and bases. Stabilization of three hydroxyl groups on the same silicon in acidic or basic medium assumes importance, in view of their use in the rational synthesis of metallosilicates. In the present work, the first examples of a silanetriol stabilized in a matrix of aliphatic or aromatic diamines are described. The reactions of [2,6-Me2C6H3N(SiMe3)Si(OH)3] (1b) with equimolar amounts of piperazine (PIP), 1,4-diazabicyclo[2,2,2]octane (DABCO), and 4,4‘-bipyridine (BPY) yield [{2,6-Me2C6H3N(SiMe3)Si(OH)3}{PIP}] (2), [{2,6-Me2C6H3N(SiMe3)Si(OH)3}{DABCO}{1,4-dioxane}0.5] (3), and [{2,6-Me2C6H3N(SiMe3)Si(OH)3}{BPY}1.5] (4), respectively. These assemblies have been characterized by elemental analysis, IR and NMR (1H and 13C) spectroscopy, and single-crystal X-ray diffraction techniques. Apart from providing an insight into the association behavior of silicon polyhydroxides in basic medium, this study also offers clues for the stabilization of metastable orthosilicic acid, Si(OH)4, in an organic soluble medium

Chemistry of Some Amino Acid Complexes of Ruthenium. Synthesis, Characterization, and DNA Binding Properties

Chemistry of Some Amino Acid Complexes of Ruthenium. Synthesis, Characterization, and DNA Binding Propertie

Stabilization of Organosilanetriols in Amine Matrices: Trapping Intermediates between RSi(OH)₃ and (RSiO₃)^3- Anions^§

Unless kinetically stabilized, hydroxides of silicon are unstable and readily self-condense through elimination of water molecules to yield Si−O−Si siloxane linkages. The condensation reaction is known to be very facile in the presence of acids and bases. Stabilization of three hydroxyl groups on the same silicon in acidic or basic medium assumes importance, in view of their use in the rational synthesis of metallosilicates. In the present work, the first examples of a silanetriol stabilized in a matrix of aliphatic or aromatic diamines are described. The reactions of [2,6-Me2C6H3N(SiMe3)Si(OH)3] (1b) with equimolar amounts of piperazine (PIP), 1,4-diazabicyclo[2,2,2]octane (DABCO), and 4,4‘-bipyridine (BPY) yield [{2,6-Me2C6H3N(SiMe3)Si(OH)3}{PIP}] (2), [{2,6-Me2C6H3N(SiMe3)Si(OH)3}{DABCO}{1,4-dioxane}0.5] (3), and [{2,6-Me2C6H3N(SiMe3)Si(OH)3}{BPY}1.5] (4), respectively. These assemblies have been characterized by elemental analysis, IR and NMR (1H and 13C) spectroscopy, and single-crystal X-ray diffraction techniques. Apart from providing an insight into the association behavior of silicon polyhydroxides in basic medium, this study also offers clues for the stabilization of metastable orthosilicic acid, Si(OH)4, in an organic soluble medium

An Expeditious and Efficient Synthesis of Highly Functionalized [1,6]-Naphthyridines under Catalyst-Free Conditions in Aqueous Medium

This is the first report of an innovative, one-pot, catalyst-free, pseudo-five-component synthesis of 1,2-dihydro[1,6]naphthyridines from methyl ketones, amines, and malononitrile in ecofriendly solvent water. The protocol avoids the use of expensive catalysts, toxic organic solvents and anhydrous condition. The approach to naphthyridines presented herein offers for the first time an unprecedented coupling which leads to the construction of both the nitrogen containing rings during the synthesis without starting from any nitrogen-containing heterocycle moiety

An Expeditious and Efficient Synthesis of Highly Functionalized [1,6]-Naphthyridines under Catalyst-Free Conditions in Aqueous Medium

This is the first report of an innovative, one-pot, catalyst-free, pseudo-five-component synthesis of 1,2-dihydro[1,6]naphthyridines from methyl ketones, amines, and malononitrile in ecofriendly solvent water. The protocol avoids the use of expensive catalysts, toxic organic solvents and anhydrous condition. The approach to naphthyridines presented herein offers for the first time an unprecedented coupling which leads to the construction of both the nitrogen containing rings during the synthesis without starting from any nitrogen-containing heterocycle moiety

Benzothiazoline Converts SO₂ to Sulfuric Acid en Route to Benzothiazole

By a new sustainable strategy, sulfur dioxide (SO2) was converted at room temperature into sulfuric acid by taking advantage of the spontaneous aerial oxidation of benzothiazoline into benzothiazole. 2-(4-Methoxy­phenyl)­benzo­thiazoline (HL) was reacted with SO2 at room temperature, and the adduct upon reaction with aerial oxygen produced 2-(4-methoxy­phenyl)­benzo­thiazolium bisulfate. The same strategy was applied on [CdL2] and [ZnL2] and found to work better than neat benzothiazoline. Bunte salt, S-(2-((pyridin-1-ium-2-ylmethyl)­amino)­phenyl) thiosulfate, was obtained upon reacting SO2 with 2-(pyridin-2-yl)-2,3-dihydro­benzo­thiazole which is an important clue for the intermediates involved in the S-oxygenation of SO2 bound on electron rich centers. This sustainable route offers a new avenue of utilizing the suicidal reaction of benzothiazoline into benzothiazole in the activation of SO2 with the help of aerial oxygen

Chemically Induced Cyclometalation of 2-(Arylazo)phenols. Synthesis, Characterization, and Redox Properties of a Family of Organoosmium Complexes

Reaction of 2-(arylazo)phenols (H2ap-R; R = OCH3, CH3, H, Cl, and NO2) with [Os(PPh3)2(CO)2(HCOO)2] affords a family of organometallic complexes of osmium(II) of type [Os(PPh3)2(CO)(ap-R)] where the 2-(arylazo)phenolate ligand is coordinated to the metal center as a tridentate C,N,O-donor. Structure of the [Os(PPh3)2(CO)(ap-H)] complex has been determined by X-ray crystallography. All the [Os(PPh3)2(CO)(ap-R)] complexes are diamagnetic and show characteristic 1H NMR signals and intense MLCT transitions in the visible region. They also show emission in the visible region at ambient temperature. Cyclic voltammetry on the [Os(PPh3)2(CO)(ap-R)] complexes shows a reversible Os(II)−Os(III) oxidation within 0.39−0.73 V vs SCE, followed by a reversible Os(III)−Os(IV) oxidation within 1.06−1.61 V vs SCE. Coulometric oxidation of the [Os(PPh3)2(CO)(ap-R)] complexes generates the [OsIII(PPh3)2(CO)(ap-R)]+ complexes, which have been isolated as the hexafluorophosphate salts. The [OsIII(PPh3)2(CO)(ap-R)]PF6 complexes are one-electron paramagnetic and show axial ESR spectra. In solution they behave as 1:1 electrolytes and show intense LMCT transitions in the visible region. The [OsIII(PPh3)2(CO)(ap-R)]PF6 complexes have been observed to serve as mild one-electron oxidants in a nonaqueous medium