Lewis Acid Activation of Pyridines for Nucleophilic Aromatic Substitution and Conjugate Addition
作者:Sarah Abou-Shehada、Matthew C. Teasdale、Steven D. Bull、Charles E. Wade、Jonathan M. J. Williams
DOI:10.1002/cssc.201403154
日期:2015.3
clean, mild and sustainable method for the functionalization of pyridines and their analogues is reported. A zinc‐based Lewis acid is used to activate pyridine and its analogues towards nucleophilic aromatic substitution, conjugate addition, and cyclization reactions by binding to the nitrogen on the pyridine ring and activating the pyridine ring core towards further functionalization.
The catalytic effect of anion-exchanged supported ionic liquid on aza-Michael-type addition
作者:Mohammad Hadi Ghasemi、Elaheh Kowsari
DOI:10.1007/s11164-016-2840-0
日期:2017.7
An effective synthesis of anion-exchanged supported ionic liquids using diatomaceous earth as solid support and its catalytic effect on the aza-Michael-type addition is described. Anionic polytungstophosphate and bisulfate ion are used in the anion-exchange step in catalyst design. In addition, the aza-Michael-type addition of various amines to 2- and 4-vinyl pyridine was examined in this article. The catalytic system can be separated from the reaction mixture and recycled in subsequent reactions. The structure of anion-exchanged supported ionic liquid on diatomaceous earth was studied by XRD, FT-IR, SEM, TGA and BET techniques. The structure of organic products was determined by 1HNMR, 13CNMR, FTIR, CHN and MASS spectroscopy.
rhodium complexes catalyze the amination of 2- and 4-vinylpyridine with secondary amines. Depending on the substrate and the reaction conditions either oxidative amination to yield the corresponding enamines 1a–8a or hydroamination to give 2-aminoethylpyridines 1b–8b occurs. In all cases products with anti-Markovnikov regioselectivity are obtained. For mechanistic studies novel cationic complexes of r
Aza-Michael-type addition reaction catalysed by a supported ionic liquid phase incorporating an anionic heteropoly acid
作者:Mohammad Hadi Ghasemi、Elaheh Kowsari、Abbas Shafiee
DOI:10.1016/j.tetlet.2016.01.107
日期:2016.3
yields using the Aza-Michael-type addition of various amines to vinyl compounds catalysed by a supported ionic liquid incorporating an anionic heteropoly acid. Different catalysts, including Lewisacids, Brønsted acids and heteropoly acids were investigated in which heteropoly acids having dual Brønsted and Lewisacid characteristics were excellent catalysts. The ionic liquid incorporating a polytungstate
Reversible C–N Bond Formation in the Zirconium-Catalyzed Intermolecular Hydroamination of 2-Vinylpyridine
作者:Samuel E. Griffin、Javier Pacheco、Laurel L. Schafer
DOI:10.1021/acs.organomet.8b00904
日期:2019.3.11
The intermolecular hydroamination of alkenes with alkylamines has been a long-standing challenge in catalysis, partially due to the near-thermoneutral nature of this transformation. Consistent with this understanding, we report the direct observation of reversible C–N bond formation in hydroamination. A bis(ureate) zirconium complex catalyzed the intermolecular hydroamination of 2-vinylpyridine. Reversible