Electrochemically promoted nucleophilic aromatic substitution in room temperature ionic liquids—an environmentally benign way to functionalize nitroaromatic compounds
作者:Hugo Cruz、Iluminada Gallardo、Gonzalo Guirado
DOI:10.1039/c1gc15303j
日期:——
tetrafluoroborate ([BMIM]BF4), 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6), 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)-imide ([BMIM]TFSI) and 1-butyl-3-methylimidazolium acetate ([BMIM]AcO) have been chosen since they have different properties in terms of solvation effects that can increase the regioselectivity of the reaction. The nucleophiles used to study the feasibility
Nitroaromatic ketones are readily prepared by nucleophilic aromatic substitution of hydrogen in nitroarenes by electrochemical oxidation. Carbanions of various ketones were added to selected nitroarenes in DMF/ketone mixtures leading to formation of the sigma(H) complexes. The reaction was promoted using potassium tert-butoxide as a base. Useful yields were achieved (80-100%) in the C-arylation of ketones. In most cases, the process proceeded with high selectivity. This new method represents an environmentally favourable route for obtaining nitroaromatic ketones.
Alkylation of Nitroaromatics with Tetraalkylborate Ion via Electrochemical Oxidation
Aromatic nucleophilic substitution reaction (S(N)Ar) is one of the most thoroughly studied reactions. Alkylation of nitroaromatics with Grignard reagents via chemical oxidation of the sigma(H)-complexes is the most general method to introduce an alkyl group into a nitroaromatic compound. This approach has considerable drawbacks, especially when more than one nitro group are present in the aromatic