A Convenient Method for the Regioselective Synthesis of 4-Alkyl(aryl)pyridines Using Pyridinium Salts
作者:Kin-ya Akiba、Y\={u}ji Iseki、Makoto Wada
DOI:10.1246/bcsj.57.1994
日期:1984.7
(81–94%). The dihydropyridines were oxidized by oxygen to give 4-alkyl(aryl)pyridines (38–68%). Grignardreagents also reacted with 1-t-butyldimethylsilylpyridinium triflate with almost complete regioselectivity (>99%) to afford the corresponding 1,4-dihydropyridines, which were easily oxidized by oxygen to give 4-substituted pyridines in higher yields than above (58–70%).
Nickel-Catalyzed Cross-Coupling of Alkyl Zinc Halides for the Formation of C(sp<sup>2</sup>)C(sp<sup>3</sup>) Bonds: Scope and Mechanism
作者:Vilasâ B. Phapale、Manuel Guisán-Ceinos、Elena Buñuel、Diegoâ J. Cárdenas
DOI:10.1002/chem.200901913
日期:2009.11.23
Optimal conditions for a general Ni‐catalysed Negishi cross‐coupling of alkyl zinc halides with aryl, heteroaryl and alkenyl halides have been determined. These conditions allow the reaction to take place smoothly, with low catalyst loading, and in the presence of a wide variety of functional groups to afford products in good yields at room temperature. DFT studies on the mechanism support the occurrence
The palladium‐catalyzed asymmetric side‐chain C(α)‐allylation of 2‐alkylpyridines, without using an external base, was developed. The high linear selectivities and enantioselectivities were achieved using new chiral diamidophosphite monodentate ligands. Given that the reaction conditions do not require an external base, this catalyst system enabled chemoselective C(α)‐allylation of 2‐alkylpyridines