21486-57-7Relevant articles and documents
One-Pot Synthesis of Highly Substituted Nicotinic Acid Derivatives Based on a Formylation Strategy of Enamino Keto Esters
Kumar, Sukeerthi,Sawant, Aarti A.,Chikhale, Rajendra P.,Karanjai, Keya,Thomas, Abraham
, p. 1645 - 1653 (2016)
(Chemical Equation Presented). A facile one-pot synthesis of 4-chloro or 4-bromonicotinic acid esters with optional 2- and 2,5-disubstitution on the pyridine ring has been developed from easily accessible enamino keto esters by a formylation followed by in situ intramolecular cyclization strategy under optimized Vilsmeier reaction conditions. The effect of the substituents on the β-carbon and the nature of the keto functionality were explored in detail to understand the mechanism of pyridine ring formation under the described conditions.
Expanding Blaise-Type Reactions towards Indium-Mediated Transformations of α-Bromo-β-keto Esters with Nitriles
Li, Luomo,Babaoglu, Emre,Harms, Klaus,Hilt, Gerhard
, p. 4543 - 4547 (2017/08/30)
The aim of this work is the identification of mild reaction conditions for the Blaise-type transformation of brominated β-keto esters with nitriles to generate enamino-substituted keto esters. The best results were obtained when a combination of indium metal (0.7 equiv.) with indium trichloride (1.6 equiv.) were applied at 60 °C for 20 to 72 hours, and these conditions could be applied to a broad range of nitriles and a significant number of different β-keto esters. The transformation of aliphatic nitriles proved to be difficult and gave only moderate yields. However, aromatic nitriles gave good yields in many cases. The applicability range of β-keto esters is acceptable while some electron-deficient aryl-substituents on the keto ester were challenging substrates. Nevertheless, we were able to expand the scope of the Blaise-type reaction towards brominated β-keto esters significantly.
Four-component synthesis of functionalized 2,2′-bipyridines based on the Blaise reaction
Hommes, Paul,Jungk, Phillip,Reissig, Hans-Ulrich
scheme or table, p. 2311 - 2314 (2011/10/31)
In situ C-acylation of the Blaise intermediate - as reported by Lee and coworkers - provides α-acyl-β-enamino esters that are versatile building blocks for the preparation of N-heterocycles. The corresponding N-acylated β-ketoenamides can be employed in the synthesis of 4-hydroxypyridine derivatives. N-Acylation of the α-acyl-β-enamino esters with 2-picolyl chloride furnished β-ketoenamides, and the subsequent TMSOTf/base-promoted intramolecular condensation reaction led to 4-hydroxy-2,2′-bipyridine derivatives. Conversion into 2,2′-bipyrid-4-yl nonaflates allowed further functionalization such as palladium-catalyzed coupling reactions. Georg Thieme Verlag Stuttgart - New York.
