In 1988 we detected an alkynyl cation on tritium decay of a l-tritiumalkyne.['l Alkynediazonium salts might also generate alkynyl cations, although it is not certain from calculations whether they decompose to nitrogen and alkynyl cations."] We have described alkynediazonium salts, which are, however, not stable in either protic or nucleophilic media.L3] The most common syntheses for alkane-or arenediazonium compounds can therefore not be applied.Alkane-and arenediazonium salts can also be obtained from sulfinylamines 1 on reaction with NO'X-(Scheme I).[,, Sulfinylamines 1 are easily prepared from amines (also bissilylated amines) and thionyl chloride.[6] We intended to synthesize alkynylsulfinylamines 3 from bissilylated alkynylamines 2 a-d by reaction with thionyl chloride and to transform these into alkynediazonium salts. To our surprise we obtained not the alkynylsulfinylamines 3, but the cyanosulfines 4 (Scheme 2). proved to be identical with an independently synthesized sample of phenyl cyan~sulfine.[~"~ The cyanosulfines 4a-d smell unpleasant to repulsive. For 4c and 4d, cisltrans isomers were detected by gas chromatography and NMR spectroscopy, but 4 a and 4 b are sterically uniform.
R -C E C -Sulfinylamines 3 and the cyanosulfines 4 are distinguishable by spectroscopy only with difficulty. To confirm the structure, 4 a was therefore treated with 2,3-dimethyl-l,3-butadiene. The product was 2-cyano-2-phenyl-4,5-dimethyl-3,6-dihydro-2 H-thiopyran-1 -oxide (5), which can only form from cyanosulfine 4a, but not from sulfinylamine 3a. Compound 5 was reduced with LiAlH, to the amine 6, which was characterized by spectroscopy (Scheme 3). Scheme 3. Diels-Alder reaction ofphenyl cyanosultine4a with 2.3-dimethyl-l-3-butadiene and reduction of the resulting dihydrothiopyran-S-oxide 5 with LiAIH,. RT = room temperature.
A Cu(II) complex of desferrithiocin from Streptomyces antibioticus was prepared and characterized. The first shell atoms, including one nitrogen and four oxygens, were arranged around the copper in a square-planar pyramide. Due to the axially Jahn-Teller-distorted Cu-O distance at 224.7 pm, a distinct Cu2Zn2superoxide dismutase mimetic activity was measured. The Cu-complex survived 600 microM bovine serum albumin and the thermodynamic stability (pK = 17.4) was not very different from that of Cu-EDTA. The electronic absorption properties, circular dichroism and electron paramagnetism were in accordance with those of the type-II copper species.
Die Reaktion von (PPh3)Pt(ViSi) (ViSi = {η2‐H2CCHSiMe2}2O) (1) mit SO2 führt nach 30 min unter Addition zum roten SO2‐Komplex (PPh3)Pt(η2‐H2CCHSiMe2OSiMe2CHCH2)(SO2) (2). Bei längerer Reaktionszeit (24 h) wird der ViSi‐Ligand vollständig abgespalten und das instabile monomere Intermediat (PPh3)Pt(SO2) cyclotrimerisiert zum stabilen Cluster [Pt(PPh3)(SO2)]3 (3). Verwendet man (PPh3)Pt(C2H4)2 (4) als Edukt, entsteht 3 unter SO2‐Atmosphäre innerhalb einer halben Stunde. 3 kristallisiert in der Raumgruppe P21/n, Z = 4, a = 1 606,1(3), b = 1 019,3(1), c = 3 624,6(5) pm, β = 93,67°, R/Rw = 0,102/0,121.
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