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

Abstract

An efficient and general method for the synthesis of 3-sulfenylindoles and 3-selenylindoles employing visible-light irradiation with graphene oxide as a promoter at room temperature has been achieved. The reaction features are high yields, simple operation, metal-free and iodine-free conditions, an easy-to-handle oxidant, and gram-scalable synthesis. This simple protocol allows one to access a wide range of 3-arylthioindoles, 3-arylselenylindoles, and even 3-thiocyanatoindoles with good to excellent yields.

Recent Progress of Visible Light-Induced the Synthesis of C(3) (Hetero)arylthio Indole Compounds

“…At the same time, GO can be recycled. Later, the same research group [25] further improved the reaction system by using 50% (w) GO as oxidant and photocatalyst, 1,2-dichloroethane (DCE) as solvent, and blue light irradiation. 3-Aryl thioindole products were obtained with 64%～91% yields under blue light irradiation for 12 h in DCE at room temperature (Scheme 13).…”

Low-Valent-Tungsten-Catalyzed Aerobic Oxidative Cross-Dehydrogenative Coupling Reaction

“…The following supporting information can be downloaded at: https:// www.mdpi.com/article/10.3390/molecules28248071/s1, the NMR data and spectra of the catalytic products. Additional references cited within the Supporting Information [19,22,23,27,28,31,32,[37][38][39].…”

“…On the other hand, 3-arylthioindoles occur abundantly in biologically active compounds (Figure 1) [24,25]. Therefore, considerable methods, such as transition metal catalysis [26,27], hyper-valent iodine catalysis [28], organo-catalysis [29], photocatalysis [30][31][32], electrocatalysis [33], etc., have been exploited for the preparation of 3-arylthioindoles. For example, Liu and coworkers reported a visible-light-induced, graphene-oxide-promoted C3-chalcogenylation of indoles for the synthesis of 3-sulfenylindoles and 3-selenylindoles with the advantages of high yields and a simple operation.…”

Na₂ – Eosin Y – Photocatalyzed Cross Dehydrogenative C−S Coupling of Arylthiols with Indole Derivatives

“…Very recently, Liangxian Liu′s group reported a graphene oxide promoted visible light mediated method [10c] . However, these methods have limitations of using toxic conditions and expensive photocatalysts, cercosporin or Rose bengal in comparison to a far less costly Na 2 ‐Eosin Y.…”