Garratt–Braverman cyclization on basic alumina: a green protocol with improved selectivity

A green protocol (compared to the existing methodology) for carrying out Garratt–Braverman cyclization has been developed. The method involves stirring a pre-absorbed bispropargyl sulfone/ether/sulfonamide over basic alumina. The reaction with sulfones was over within 10–15 min at room temperature whereas for the ether/sulfonamide the reaction took 6–8 h at 130 °C. The products, aryl naphthalene derivatives, are obtained by simple filtration through Celite, in excellent yields.     

Optimization of Electrical Conductivity of SA-graphene Nanocomposites Using Response Surface Methodology

Synthesis and characterization of 4-{(E)-[(5-bromo-2-hydroxyphenyl)methylidene]amino}-N-carbamimidoylbenzene-1-sulfonamide(SA) and its composites with graphene(SA-GF) were performed. Compound SA and SA-GF were characterized by FTIR and ¹H NMR. The GF dispersion in the composites was analyzed by means of scanning electron microscopy(SEM) for morphology. Thermal properties of SA and nanocomposites were investigated using differential thermal analysis(DTA) and thermogravimetric analysis(TGA). The optimum electrical conductivity of the new sulfonamide-based Schiff base was determined to be 1.78×10^–5 S/cm at a frequency of 9923 Hz, an applied voltage of –19 V, a mass fraction of 9.38% for graphene loading using a central composite design in the response surface methodology. The significance of the selected parameters(frequency, voltage and GF amount) in the model was determined by the analysis of variance(ANOVA). The results showed that frequency and graphene loading represent important model terms and have considerable effects on the conductivity of SA.     

Monitoring intracellular pH fluctuation with an excited-state intramolecular proton transfer-based ratiometric fluorescent sensor

Intracellular pH is a key parameter related to various biological and pathological processes. In this study, a ratiometric pH fluorescent sensor ABTT was developed harnessing the amino-type excited-state intramolecular proton transfer (ESIPT) process. Relying on whether the ESIPT proceeds normally or not, ABTT exhibited the yellow fluorescence in acidic media, or cyan fluorescence in basic condition. According to the variation, ABTT behaved as a promising sensor which possessed fast and reversible response to pH change without interference from the biological substances, and exported a steady ratiometric signal (I₄₇₈/I₅₄₆). Moreover, due to the ESIPT effect, large Stokes shift and high quantum yield were also exhibited in ABTT. Furthermore, ABTT was applied for monitoring the pH changes in living cells and visualizing the pH fluctuations under oxidative stress successfully. These results elucidated great potential of ABTT in understanding pH-dependent physiological and pathological processes.     

Determination of sulfonamide residues in cultured sea cucumber by pre-column derivatization capillary electrophoresis with fluorescence detection

A simple and mild method for the separation of sulfonamide residues based on a condensation reaction with O-phthalaldehyde solution (OPA) as labeling reagent with capillary electrophoresis has been developed. A 58.5 cm × 50 μm i.d. (50 cm effective length) untreated fused-silica capillary was used. To optimize the separation conditions, the background electrolyte concentration, pH, column temperature, voltage and other factors were evaluated. The optimal separation conditions were as follows: 20 mmol L^?1 borate buffer; pH 9.1; column temperature 20 °C; separation voltage 18 kV, pressure 50 mbar and injection time 8 s. Under the optimal conditions, 10 kinds of sulfonamide derivatives could be well-separated within 8 min, and the linear ranges were 0.35–100 μg kg^?1. The detection limit (at a signal-to-noise ratio of 3) was in the range of 0.12–0.25 μg kg^?1, and the quantification limit (at a signal-to-noise ratio of 10) was in the range of 0.35–0.70 μg kg^?1. The sulfonamide residues from cultured sea cucumber samples were determined under the optimal conditions with satisfactory results.     

Tandem chalcone-sulfonamide hybridization,cyclization and further Claisen–Schmidt condensation: Tuning molecular diversity through reaction time and order and catalyst

We here report the synthesis of novel chalcone-sulfonamide compounds based on the hybridization at 2′ position and nitro substitution at the side chalcone phenyl ring followed by tandem cyclization into quinolinone derivatives and then a further aldol condensation only as a function of the reaction time. Therefore, for the first time, we have controlled the sequential preparation of chalcone-sulfonamide hybrids, quinolinones and then (E)-3-ene-2,3-dihydroquinolinones simply stopping reaction over increasing time periods. Furthermore, a new molecular scaffold based on a chalcone-(bis)sulfonamide hybrid has been gotten through changing the sequence of coupling reactions and catalyst. This study means practical and useful ways of constructing in high yields new biologically active compounds bearing diversified molecular scaffolds.     

A facile electrochemical method for the synthesis of new sulfonamide derivatives of potential biological significance

The electrochemical synthesis of some new sulfonamide derivatives was carried out via the electrochemical oxidation of 2,3-dihydrophthalazine-l,4-dione （1） in the presence of arylsulfinic acids （2a and 2b） as nucleophiles. The results show that, the electrogenerated phthalazine-l,4-dione （lox） participates in a Michael type addition reaction with 2a or 2b and via an EC mechanism to produce the corresponding sulfonamide derivatives. This method provides a one-pot procedure for the synthesis of new sulfonamide derivatives of potential biological significance in good yields without using toxic reagents at a carbon electrode in an environmentally friendly manner.     

Asymmetric hydroamination of aminoallenes catalyzed by titanium and tantalum complexes of chiral sulfonamide alcohol ligands

A series of bidentate sulfonamide alcohol ligands with varying steric and electronic properties was synthesized. The titanium and tantalum complexes of these ligands, prepared in situ from either Ti(NMe₂)₄ or Ta(NMe₂)₅, were used as catalysts for the asymmetric hydroamination of 6-methyl-hepta-4,5-dienylamine, giving exclusively the α-vinylpyrrolidine product. The titanium derived catalysts gave products with low stereoselectivity, up to 11%ee favoring (+)-2-(2-methyl-propenyl)-pyrrolidine, while the tantalum derived catalysts gave products with higher and opposite stereoselectivity, up to 34%ee favoring (−)-2-(2-methyl-propenyl)-pyrrolidine.     

Synthesis of Patent Blue derivatized hydrophilic dendrons dedicated to sentinel node detection in breast cancer

In the last decade, methods for the precise localization of sentinel lymph node (SLN) have drawn tremendous attention by oncology surgeons and researchers in the field of medical diagnosis. The accurate identification and characterization of lymph nodes by imaging has important therapeutic and prognostic significance in patients with newly diagnosed cancers. The SLN is the first lymph node that receives lymphatic drainage from the site of a primary tumor. Two biocompatible dendronized phosphonates, one bearing a Patent Blue (PB VF) dye at its periphery, where synthesized. Indeed, such a blue dye is currently injected to label the lymph node system for its per-operative detection. Therefore, developing chemistry of Patent Blue VF to optimize early diagnosis is of great current interest.     

CRYSTAL AND MOLECULAR STRUCTURE OF THE SPIRODIPHOSPHITE ESTER 3,9-DIMETHOXY-2,4,8,10-TETRAOXA-3,9-DIPHOSPHASPIRO[5.5]UNDECANE

Abstract

The crystal and molecular structure of the strainless phosphite ester MeOP(OCH₂)₂C(CH₂O)₂POMe determined by x-ray means is reported. The methoxy groups are in axial positions on the chair-form-six-membered rings.