6268-96-8Relevant academic research and scientific papers
Enantioselective dicarbofunctionalization of (: E)-alkenyloxindoles with pyridinium salts by chiral Lewis acid/photo relay catalysis
Zhang, Dong,Dong, Shunxi,He, Qianwen,Luo, Yao,Liu, Yun,Liu, Xiaohua,Feng, Xiaoming
supporting information, p. 12757 - 12760 (2020/11/02)
A highly efficient enantioselective dicarbofunctionalization reaction of (E)-alkenyloxindoles with pyridinium salts was realized. The process includes the chiral N,N′-dioxide-Sc(iii) complex-catalyzed regio-, diastereo-, and enantioselective [3+2] cycloaddition reaction and the following photo-promoted aza-Norrish II type rearrangement. A series of 2-pyridyl substituted oxindole derivatives were obtained in good yields with moderate to good diastereo- and enantioselectivities. This journal is
Kinetics and Mechanism of the Pyridinolysis of Phenacyl Bromides in Acetonitrile
Koh, Han Joong,Han, Kwang Lae,Lee, Hai Whang,Lee, Ikchoon
, p. 4706 - 4711 (2007/10/03)
Kinetic studies of the reactions of substituted phenacyl bromides (YC6H4COCH2Br) with pyridines (XC5H4N) are carried out in acetonitrile at 45.0°C. A biphasic Bronsted plot is obtained with a change in slope from a large (βX ? 0.65-0.80) to a small (βX ? 0.36-0.40) value at pKao = 3.2-3.6, which can be attributed to a change in the rate-determining step from breakdown to formation of a tetrahedral intermediate in the reaction path as the basicity of the pyridine nucleophile increases. This mechanism is supported by the faster rates with pyridines than with anilines and the change of cross-interaction constant ρXY from a large positive (ρXY ? +1.4) to a small positive (ρXY ? +0.1) value. The large magnitude of Hammett ρX (= -5.5 to -6.9) values for the pyridines with electron-withdrawing substituents and positive deviations of the π-acceptors, p-CH3CO and p-CN, are quite similar to those for the pyridinium ion formation equilibria. The activation parameters are also in line with the proposed mechanism.
