691-64-5Relevant articles and documents
Chemiluminescent and non-chemiluminescent ozonations of selected electron-rich alkynes in halomethanes
Schank, Kurt,Beck, Horst,Werner, Frank
, p. 1611 - 1624 (2007/10/03)
Alkynes of sufficiently high nucleophilicity react with electrophilic O3 under conversion of the alkyne function to a vicinal dicarbonyl function. Contrary to earlier investigations with alkylated or arylated acetylene, products of complete C-C cleavage were not found as primary products, and, beyond that, peroxidic reaction products were absent. Trimethylsilylated alkynes reacted with O3 either by uptake of two or three O-atoms, but again without C-C cleavage or formation of peroxides. Two particularly electron- rich, symmetrically substituted alkynes revealed strong chemiluminescence during ozonation at low temperature, whereas this behavior was not observed with unsymmetrically substituted alkynes. The results are summarized in terms of a mechanistic discussion.
Compositions for reducing abnormal stimulation of endothelin receptors and novel compounds
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, (2008/06/13)
The invention relates to the new use and the new products of formula (I): STR1 in which: R1 =represents hydroxyl, alkyl, alkenyl, alkynyl, alkoxy, alkylthio, formyl, cycloalkyl, optionally interrupted by heteroatoms, R2, R3 represent in particular halogen, mercapto, acyl, carboxy, nitro, cyano, amino, carbamoyl, R4, --OR4 with R4 representing in particular hydrogen, alkyl, alkenyl, alkynyl, acyl, amino, --(CH2)m1 --S(O)m2 --X--R10 with m1=0 to 4, m2=0 to 2, X represents a single bond or --NH--, --NH--CO--, --NH--CO--NH--, and R10 represents alkyl, alkenyl or aryl, and Y represents optionally substituted aryl, these products being in all the isomer forms and the salts, as medicaments.
Electro-organic reactions. Part 27. The mechanism of cathodic cleavage of activated esters; oxalates, squarates and oxamates
Islam, Nazar-ul,Sopher, David W.,Utley, James H.P.
, p. 959 - 970 (2007/10/02)
Esters of oxalic acid, 3,4-dihydroxy-3-cyclobutene-1,2-dione (squaric acid), and oxamic acid, are reduced cathodically at modest potentials. In aprotic solvent, and on the cyclic voltammetric time scale, the esters are cleaved to the corresponding alkane. For oxalates, the mechanism of cathodic cleavage was investigated thoroughly by voltammetry, coulometry, and detailed product analysis. On the time scale of controlled potential electrolysis the rapid electrogenerated base-catalysed hydrolysis of the esters by adventitious water competes with cathodic cleavage. Similarly, rapid base-catalysed transesterification involving oxalates and added alcohols is observed which provides a practical method of reductively cleaving alcohols to alkanes by co-electrolysis of a mixture of alcohol and readily available oxalate (e.g. diethyloxalate). The leaving group in such cathodic fragmentation is the half-ester anion and the efficiency of reaction depends on the stability of the other, radical, fragment.
