Bismuth Nitrate-Catalyzed Versatile Michael Reactions
作者:Neeta Srivastava、Bimal K. Banik
DOI:10.1021/jo026550s
日期:2003.3.1
Bismuth nitrate-catalyzed versatile Michael reaction was developed to reduce the complications that characterize the current standard Michael reaction and used for facile preparation of organiccompounds of widely different structures. For example, several substituted amines, imidazoles, thio compounds, indoles, and carbamates were prepared at room temperature by following this method. In contrast
carbon-containing nucleophiles to cyclicenones. Using this conjugate addition reaction, a variety of different nucleophiles can react with a range of cyclicenones in the presence of p-toluenesulfonic acid under solvent-free ultrasound irradiation conditions affording the corresponding C–N or C–C adducts in good to excellent yields. Comparatively, performing the reaction under ultrasound irradiation gives
A new green chemical method for the aza-Michael reaction of nitrogenheterocycles with enones in water as a solvent without the use of any catalysts under high-pressure conditions is described.
additions of heterocyclic compounds, such as indoles, pyrrole, pyrazole, and imidazole, have been demonstrated. Hafnium chloride effectively catalyzed the conjugate addition of indoles to α,β-unsaturatedcarbonyl compounds, and the addition product was obtained in high yield. The reaction of pyrrole was also catalyzed by HfCl4 or ScCl3, and produced 2,6-dialkylated pyrroles up to 99% yields. Furthermore
Pyrrole, pyrazole and imidazole undergo conjugate addition with α,β-unsaturated ketones in the presence of a catalytic amount of hafnium chloride at room temperature. Although the reaction of pyrrole gave 2,5-substituted C-adduct mainly, those of pyrazole and imidazole gave the corresponding N-adducts in excellent yields.