Halodediazoniations of dry arenediazonium o-benzenedisulfonimides in the presence or absence of an electron transfer catalyst.: Easy general procedures to prepare aryl chlorides, bromides, and iodides

The paper reports the results of a wide study aimed at preparing aryl chlorides 3 (19 examples), bromides 4 (19 examples), and iodides 5 (9 examples) by halodediazoniation of dry arenediazonium o-benzenedisulfonimides 1 with tetraalkylammonium halides 2. The reactions were carried out in anhydrous acetonitrile at room temperature (similar to 20 degrees C) in the presence of copper powder and at 60 degrees C or room temperature without the catalyst. In optimal conditions the yields were from good to excellent (60 reactions, 61-94% yield), with only a few exceptions (8 reactions, 51-55% yield). A good amount of the o-benzenedisulfonimide (7) was always recovered from the reactions and could then be reused to prepare salts 1. An interesting aspect of this research is the surprising role of the anion of o-benzenedisulfonimide (9) as an electron transfer agent.