89693-83-4Relevant academic research and scientific papers
Rh(II)-catalyzed intramolecular annulation of N-sulfonyl 1,2,3-triazoles with indole derivatives: A new method for synthesis pyranoindoles
Xie, Hui,Yang, Jian-Xin,Bora, Pranjal Protim,Kang, Qiang
supporting information, p. 3014 - 3021 (2016/05/19)
A direct and highly stereoselective approach for the synthesis of Z-alkenyl-pyranoindoles had been developed by utilizing Rh(II)-catalyzed intramolecular cyclization of N-sulfonyl-1,2,3-triazoles with indole derivatives. A variety of pyranoindoles were obtained in 44-93% yields. Moreover, a more convenient synthesis of pyranoindoles starting from terminal alkyne was realized via a Cu-Rh sequentially catalyzed one-pot cascade reaction.
Formation of diazohydroxides ArN2OH in aqueous acid solution: Polarographic determination of the equilibrium constant KR for the reaction of 4-substituted arenediazonium ions with H2O
Sienkiewicz, Andrzej,Szymula, Marta,Narkiewicz-Michalek, Jolanta,Bravo-Diaz, Carlos
, p. 284 - 289 (2014/04/17)
In aqueous acid (pH 2+ decompose spontaneously through the rate-limiting formation of the extremely unstable aryl cation that reacts with any nucleophile present in its solvation shell (D N-‰+-‰AN mechanism). However, in weak acidic and alkaline solutions, ArN2+ react with H2O and OH- at the terminal nitrogen to give azo adducts of the type ArN2OH that are in equilibrium with the parent ArN2 +. The diazohydroxide, in this case an acid, is in equilibrium with its conjugate base, and diazoate ArN2O-. The equilibrium constant for reaction with OH- has been determined for a limited number of ArN2+ from kinetic measurements but not with H2O (KR). Here, we have exploited the electrochemical properties of ArN2+ to determine, for the first time, the equilibrium constants KR of formation of 4-substituted X-ArN 2OH (Xi￡H, Me, MeO, Br, and NO2), which can decompose in several ways including Z-E isomerization or further reaction with OH- to give diazoate ArN2O-. The technique applied was differential pulse polarography, which is very selective and sensitive. The determined pKR values are 5-6, and they are somewhat higher than those obtained for the reaction of ArN2+ with alcohols ROH (pKDE-‰=-‰3-5) under similar acidic conditions. The KR values are not very sensitive to changes in the nature of the substituent in the aromatic ring and a linear Hammett plot with a slope of ρ-‰=-‰0.58 was obtained.
