Ambident electrophilic character of thioxophosphoranesulphenyl bromides =P(S)SBr. A novel observation of electrophilic addition to a Carbon–Carbon double bond
α,β-Unsaturated arylhydrazones (1) reacted with nitric oxide (NO) in the presence of a trace of oxygen to give α- (2a–2c, 2e, and 2f) or β-nitro (2d and 2g) unsaturated hydrazones in good yield and with high stereoselectivity. The reaction occurs most likely by an electrophilic addition of NO2 to the carbon–carbon double bond of 1 at its α- or β-position.
Abstract4-Pyrones bearing electron-donating and electron-withdrawing groups react with nonstabilized azomethine ylides to form pyrano[2,3-c]pyrrolidines in moderate to good yields. The reaction proceeds chemoselectively as a 1,3-dipolar cycloaddition of the azomethine ylide at the carbon–carbon double bond of the pyrone activated by the electron-withdrawing substituent. The reactivity of 4-pyrones toward azomethine ylides was rationalized by computational studies with the use of reactivity indexes. The pyrano[2,3-c]pyrrolidine moiety could be modified, for example by a ring-opening transformation under the action of hydrazine to provide pyrazolyl-substituted pyrrolidines.
Abstract
The Raman spectra of cis-1,4-, trans-1,4-, and 3,4-polyisoprene are presented, and the frequencies are classified by configurational structure type. The stretching frequency of the carbon-carbon double bond vibrations are used to describe structure content. Only Raman bands characteristic of total 1,4 content and total vinyl content can be observed. Tentative values of structure content determined by both peak height and peak area are presented for two mixed structure rubbers.
RNA-Seq used to identify ipsdienone reductase (IDONER): A novel monoterpene carbon-carbon double bond reductase central to Ips confusus pheromone production