Stable Bromonium and Chloronium Salts

Palladium-catalyzed synthesis of N-arylated carbazoles using anilines and cyclic diaryliodonium salts

“…Cyclic diarylbromonium salts are considerably less explored than their iodonium congeners as can be seen by only a handful of synthetic methods described in the literature [32,36–41]. In general, bromonium salts are more reactive but have similar reaction behaviour [32,36].…”

“…Thus they could be helpful substrates for the synthesis of N -arylcarbazoles from anilines. With this in mind, we initially focussed on the synthesis of dibenzo[ b , d ]bromolium chloride ( 5 ) using a procedure published by Sandin and Hay in 1952 [41] (Scheme 3). …”

“…Diazotation of 4 *HCl and cyclization gave the cyclic diarylbromonium chloride 5 as an off-white powder in good isolated yield (52%) (Supporting Information File 1) [41]. Finally, 5 could be converted into the corresponding diarylbromonium triflate 6 with silver trifluoromethanesulfonate in quantitative yield (Supporting Information File 1).…”

Hypervalent Aryl-, Alkynyl-, and Alkenyl-λ³-bromanes

“…2,3 In contrast, the first synthesis of diaryl-l 3 -iodanes was reported in the late 19th century by Hartmann and Meyer. 4 The thermolysis of these aryldiazonium salts 1 involves generation of highly reactive aryl carbocations with evolution of nitrogen, the carbocations being captured in an intramolecular fashion by the neighboring halogen atoms to give the aryl-l 3 -haloganes 2 and 3.…”

Hypervalente Bromverbindungen: kleine Analoga von hypervalenten Iodverbindungen oder “Enfants Terribles”?

“…Die Bildung des Diazoniumsalzes von Amin 1 mit anschließender thermischer Zersetzung zur l 3 -Broman-Verbindung 2 wurde bereits 1952 publiziert (Schema 1). [2] Obwohl diese Synthesemethode recht einfach erscheint, liefert die intermolekulare Addition von Arylkationen an Arylbromide, unabhängig von deren Vorstufen und der Herstellungsmethode, die hypervalenten Bromverbindungen nur in geringen Ausbeuten. [3] Die bisher einzige nützliche Synthese hypervalenter Bromverbindungen ist der Ligandenaustausch an Bromtrifluorid (3).…”