NITRATION OF AROMATIC COMPOUNDS

摘要

A method of nitrating electron-deficient carbocyclic or heterocyclic aromatic compounds such as pyridines, diazines and triazines and benzenoid aromatics having electron-withdrawing substituents involves first reacting the aromatic species with a sulphilimine species or with the corresponding N-alkali metal salt thereof to generate an N-(hetero)aryl-S,S-dialkyl, diaryl or alkylarylsulphilimine derivative. This intermediate may then be readily oxidised under relatively mild conditions using a peroxycarboxylic acid such as m-chloroperbenzoic acid, peracetic or peroxytrifluoroacetic acid. Good yields of nitrated products are obtained including some previously unprepared. The novel N-alkali(alkylaryl)sulphilimine reagents are prepared by reacting an alkali metal hydride, an alkali metal hydrogenous base or an alkyl lithium with the corresponding sulphilimine. Preferred salts are the N-lithio types and the preferred sulphilimine is diphenylsulphilimine. Where the salt is used reaction should be in an aprotic solvent but if the sulphilimine per se is the reagent a polar solvent is used.