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Azomethines (Schiff's bases) derived from a,b-unsatd. a-fluoroaldehydes can be deprotonated with lithium diisopropylamide. The resulting "anions" or, correctly, 3-fluoro-1-azapentadienyl lithium compds. are conformationally mobile. While eight different ...
A review with 64 refs., including discussion of the structural flexibility of organometallic species, the stereochem. of 2-alkenylmetal compds., and the origin of the endo effect. [on SciFinder (R)] ...
Hydrogenolytic ring cleavage of gem-difluorocyclopropanes, e.g. I and II, occurs exclusively at the carbon-carbon bond opposite to the halogen-bearing center and affords mainly gem-difluoroalkanes, e.g. MeCH2CF2(CH2)3Me and III, resp. The intermediacy of c ...
Studies on the sp-sp intermolecular coupling reactions with the palladium water-soluble catalyst prepared in situ from palladium(II) acetate and sulfonated triphenylphosphine P(C6H4-m-SO3Na)(3) (TPPTS) in a homogeneous acetonitrile-water system, without Cu ...
Acid promoted epoxide ring opening of 2-exo-cyano-5-exo,6-exo-epohy-7-oxa-bicyclo[2.2.1]hept-2-endo-yl acetate is accompanied by a Wagnet-Meerwein (pinacolic) rearrangemant when run in CH2Cl2/HSO3-F and by endo acetoxy group participation when run in CF3CH ...
Using the Car-Parrinello method, the authors have obtained unforeseen structures for the low-lying isomers of Si45 and other midsized Si clusters. They are formed by two shells of atoms, the outer one (cage) being fullerenelike and the inner one (core) con ...
Complex of general formula I in which R1, R2 and R3, which may be identical or different, represent separately a linear or branched alkyl radical of 1 to 5 carbon atoms, or, together with the nitrogen atom to which they are attached, a heterocyclic ...
Syntheses of (+/-)-2-exo-cyano-1-methyl-7-oxabicyclo[2.2.1]hept-5-en-2-endo-yl acetate (1) and of (+/-)-1-methyl-7-oxabicyclo[2.2.1]hept-5-en-2-one (2) are reported. The additon of PhSeCl to 1 afforded (+/-)-5-endo-chloro-2-exo-cyano-1-methyl-6-exo-(phenyl ...
Stable negative ions containing up to sixteen silicon atoms have been measured by mass spectrometry in RF power-modulated silane plasmas for amorphous silicon deposition. These hydrogenated silicon cluster ions reach much higher masses than the positive io ...
A new strategy based upon the intramol. SNAr reaction was developed for the synthesis of I, the 14-membered F-O-G macrocyclic ring system of teicoplanin. Thus, treatment of acyclic precursor II (X = F) with CsF or K2CO3/18-crown-6 in DMF at room temp. for ...
