One-Pot, Metal-Free Conversion of Anilines to Aryl Bromides and Iodides

Abstract

A metal-free synthesis of aryl bromides and iodides from anilines via halogen abstraction from bromotrichloromethane and diiodomethane is described. This one-pot reaction affords aryl halides from the corresponding anilines in moderate to excellent yields without isolation of diazonium salts. The transformation has short reaction times, a simple workup, and insensitivity to moisture and air and avoids excess halogenation. DFT calculations support a SRN1 mechanism. This method represents a convenient alternative to the classic Sandmeyer reaction.

Cyanation of Anilines to Aryl Nitriles Using tert‐Butyl Isocyanide: A Simple and Copper‐free Procedure

“…It is note‐worthy that the desired product was not observed in this radical trap experiment. The result of this was different from a previous reported literature . These differences arise as different reaction condition was employed in the current study (NaNO 2 , TEMPO, solventless, and 50 °C) compared to previous study …”

“…While the tert‐ butyl radical generated in this reaction, which could further reacts with the acetoxy radical ( B ) to form ester ( D ) and the [M+1] of ester ( D ) was confirmed with GCMS analysis (see Appendix S1, Supporting Information). The mechanism for the synthesis of benzonitriles is consistent with the synthesis of aryl bromides and iodides formed by reacting anilines with the bromotrichloromethane and diiodomethane …”

“…The result of this was different from a previous reported literature. 28 These differences Figure 1. Synthetic route towards the preparation of aryl nitriles.…”

“…arise as different reaction condition was employed in the current study (NaNO 2 , TEMPO, solventless, and 50 C) compared to previous study. 28 Based on our understanding of Sandmeyer-type and radical reactions, a plausible mechanism for the formation of 3a was proposed as shown in Figure 3. It would appear that the aniline is first reacted with sodium nitrite to form diazonium salt (intermediate A).…”

Direct Transformation of Arylamines to Aryl Halides via Sodium Nitrite and N‐Halosuccinimide

“…However, maintenance of low temperature, numerous competing reactions, time‐consuming workup, diazonium salt isolation, and excess halogenation underscore the need to develop complementary approaches for transforming aryl amines to aryl halides . In this regard, recently Stack and co‐workers disclosed a metal‐free synthesis of aryl bromides and iodides from anilines via halogen abstraction from bromotrichloromethane and diiodomethane without isolation of the diazonium salt . This protocol, however, requires acetic acid for the formation of diazonium salt and the substrates bearing strong electron‐donating groups or heterocyclic amines furnished products in low yields limiting its practical use.…”