Regioselective synthesis of 2,3′-biindoles mediated by an NBS-induced homo-coupling of indoles

Abstract

Mild conditions have been developed to achieve NBS-induced homodimerization of indole derivatives with excellent regioselectivity at 15 °C in high efficiency. This method provides a simple route to a 2,3'-linked biindolyl scaffold from the electron-rich to moderately electron-poor indoles. In addition, [3,2-a]carbazole derivatives can also be prepared through this method.

Visible-Light-Induced, Graphene Oxide-Promoted C3-Chalcogenylation of Indoles Strategy under Transition-Metal-Free Conditions

“…However, the reaction substrates are expensive and difficult to obtain for this synthesis method. In continuation of our work on indole chemistry [ 86 , 87 , 88 , 89 , 90 , 91 , 92 ] and GO-promoted C-H functionalisation of indoles [ 93 ], herein, we wish to report the combination of GO and blue LEDs, which works in synergy to efficiently promote the organo chalcogenylation (S and Se) of indoles in DCE under air atmosphere by using commercially available substrates. The highlight of this work is that GO not only acts as an oxidant, but as a photocatalyst as well.…”

Synthesis of selenium‐containing biindolyls and their Diels–Alder reaction toward the synthesis of heteroannulated [a]‐ and [c]‐carbazoles

“…Therefore, biindolyl was used as a key intermediate in the synthesis of indolocarbazole derivatives . On the other hand, the synthesis of 2,3′‐indolo[3,2,‐ b ]indole3a to obtain arcyriaflavin derivatives also attracted attention.…”

Facile and Mild Access to Fluorescent Ladder-Type Indolo[3,2-a]carbazoles via Cascade Annulation

“…12,13 The current approaches involved in the synthesis of indolo[3,2-a]carbazole framework are accessed either from the 2,3′-bisindolyl or indoles. While these methods have eased the synthesis of this important indolo[3,2-a]carbazole motif, the often harsh conditions, for example, high reaction temperatures, 13,14 metal catalysis 13,15,16a or multistep synthesis, 16b-d and the limited functional group toler-ance or substrate scopes [17][18][19][20][21] restrict the further structural tuning of the photophysical properties and systematic study of structure-photophysical relationships (SPPR). Therefore, the necessity for the development of mild conditions to access diverse polycyclic indolo[3,2-a]carbazoles is underscored.…”

“…Interestingly, the yield increased significantly to 44% when the reaction was exposed to oxygen from a balloon (entry 12). However, other oxidants were not capable for increasing the yields (entries [13][14][15][16][17][18].…”