Dual Palladium(II)/Tertiary Amine Catalysis for Asymmetric Regioselective Rearrangements of Allylic Carbamates

The streamlined catalytic access to enantiopure allylic amines as valuable precursors towards chiral β‐ and γ‐aminoalcohols as well as α‐ and β‐aminoacids is desirable for industrial purposes. In this article an enantioselective method is described that transforms achiral allylic alcohols and N‐tosylisocyanate in a single step into highly enantioenriched N‐tosyl protected allylic amines via an allylic carbamate intermediate. The latter is likely to undergo a cyclisation‐induced [3,3]‐rearrangement catalysed by a planar chiral pentaphenylferrocene palladacycle in cooperation with a tertiary amine base. The otherwise often indispensable activation of palladacycle catalysts by a silver salt is not required in the present case and there is also no need for an inert gas atmosphere. To further improve the synthetic value, the rearrangement was used to form dimethylaminosulfonyl‐protected allylic amines, which can be deprotected under non‐reductive conditions.     

Electrochemiluminescence Bioassays with a Water‐Soluble Luminol Derivative Can Outperform Fluorescence Assays

The most efficient and commonly used electrochemiluminescence (ECL) emitters are luminol, [Ru(bpy)₃]²⁺, and derivatives thereof. Luminol stands out due to its low excitation potential, but applications are limited by its insolubility under physiological conditions. The water‐soluble m‐carboxy luminol was synthesized in 15 % yield and exhibited high solubility under physiological conditions and afforded a four‐fold ECL signal increase (vs. luminol). Entrapment in DNA‐tagged liposomes enabled a DNA assay with a detection limit of 3.2 pmol L^?1, which is 150 times lower than the corresponding fluorescence approach. This remarkable sensitivity gain and the low excitation potential establish m‐carboxy luminol as a superior ECL probe with direct relevance to chemiluminescence and enzymatic bioanalytical approaches.     

Some reactions of ferrocyanides and ferricyanides

I. The ferrocyanides of Copper. Cadmium, Zinc, Nickel and Cobalt are more difficultly soluble than the corresponding ferricyanides. II. The ferricyanides of Cu, Cd, Ni, Co, Zn react with sodium oxalate or potassium oxalate forming alkali double oxalates of these metals and alkali ferricyanide. III. The ferricyanides of Cu, Cd, Ni, and Zn react with ammonium oxalate forming the ammonium double oxalates of these metals and ammonium ferricyanide. IV. However cobalt ferricyanide is very difficultly soluble in ammonium oxalate.     

Reaction of thiocyanates with ironcyanogen compounds of silver

Silver fenocyanide as well as Silver ferricyanide are converted into silver thiocyanate by treating with thiocyanate ions, while feirocyanide ions or ferricyanide ions are formed at the same time. Silver ferrocyanide as well as silver ferricyanide are dissolved by solutions of thiocynates of higher concentrations.     

The detection of cobalt by the microcosmic salt bead

I. The fact, that the blue violet colour of the microcosimic salt bead of cobalt is changed into blue by addition of Na₂CO₃ K₂CO₃, K₂CO₃ NA₂HPO₄ or NA₃PO₄is explained by the formation of pyrophosphate in the melt. II. K₂Na₂P₂O₇ if melted together with CoCl₂ forms blue porcelaneous masses, completely soluble in water.     

Über das 2, 4, 6-Trichlor-3-Bromphenol und das 2-Chlor-4, 6-Dibromphenol

Ohne Zusammenfassung     

Einwirkung von Oxalaten auf die blauen Eisenzyanverbindungen

Ohne ZusammenfassungFrühere Mitteilungen: Z. anorg. allg. Chem.49 (1906) 443; Mh. Chem.43 (1922) 373, bzw. S.-B. Akad. Wiss. Wien (II b)131 (1922) 373; Mh. Chem.44 (1923) 97, bzw. S.-B. Akad. Wiss. Wien (IIb)132 (1923) 97; Z. anorg. allg. Chem.197 (1931) 287,197 (1931), 289.     

Thiazole orange and Cy3: improvement of fluorescent DNA probes with use of short range electron transfer

Thiazole orange was synthetically incorporated into oligonucleotides by using the corresponding phosphoramidite as the building block for automated DNA synthesis. Due to the covalent fixation of the TO dye as a DNA base surrogate, the TO-modified oligonucleotides do not exhibit a significant increase of fluorescence upon hybridization with the counterstrand. However, if 5-nitroindole (NI) is present as a second artificial DNA base (two base pairs away from the TO dye) a fluorescence increase upon DNA hybridization can be observed. That suggests that a short-range photoinduced electron transfer causes the fluorescence quenching in the single strand. The latter result represents a concept that can be transferred to the commercially available Cy3 label. It enables the Cy3 fluorophore to display the DNA hybridization by a fluorescence increase that is normally not observed with this dye.