||Transition-Metal-Free Synthesis of Carbazoles and Indoles by an SN Ar-Based "Aromatic Metamorphosis" of Thiaarenes.
Bhanuchandra, M ,
Murakami, Kei ,
Vasu, Dhananjayan ,
Yorimitsu, HidekiOsuka, Atsuhiro
Angewandte Chemie - International Edition
10238 , 2015-07-15 , wiley
Dibenzothiophene dioxides, which are readily prepared through oxidation of the parent dibenzothiophenes, undergo nucleophilic aromatic substitution with anilines intermolecularly and then intramolecularly to yield the corresponding carbazoles in a single operation. The "aromatic metamorphosis" of dibenzothiophenes into carbazoles does not require any heavy metals. This strategy is also applicable to the synthesis of indoles. Since electron-deficient thiaarene dioxides exhibit interesting reactivity, which is not observed for that the corresponding electron-rich azaarenes, a combination of a thiaarene-dioxide-specific reaction with the SN Ar-based aromatic metamorphosis allows transition-metal-free construction of difficult-to-prepare carbazoles.