A Probable Hydrogen-Bonded Meisenheimer Complex: An Unusually High SNAr Reactivity of Nitroaniline Derivatives with Hydroxide Ion in Aqueous Media

作者：Imoto Mitsutaka; Matsui Yasunori; Takeda Motonori; Tamaki Akihiro; Taniguchi Hisaji; Mizuno Kazuhiko^*; Ikeda Hiroshi

来源：Journal of Organic Chemistry, 2011, 76(15): 6356-6361.

DOI：10.1021/jo2007219

Observations show that nitroanilines exhibit an unusually high SNAr reactivity with OH- in aqueous media in reactions that produce nitrophenols. SNAr reaction of 4-nitroaniline (2a) in aqueous NaOH for 16 h yields 4-nitrophenol (4a) quantitatively, whereas a similar reaction of 4-nitrochlorobenzene (1a) gave 4a in 2% yield together with recovered la in 97%, suggesting that the leaving ability of the NH2 group far surpasses that of Cl under these conditions. An essential feature of SNAr reactions of nitroanilines is probably that the NH2 leaving group participates in a hydrogen-bonding interaction with H2O. Density functional theory (DFT) calculations for a set of 4-nitroaniline, OH-, and H2O suggest a possible formation of a Meisenheimer complex stabilized by hydrogen-bonding interactions and a six-membered ring structure. The results obtained here contrast with conventional SNAr reactivity profiles in which nitroanilines are nearly unreactive with nucleophiles in organic solvents.

• 出版日期2011-8-5