Thio- and Selenocyanation Reactions of Quinone Imines—Derivatives of Pyrido[1,2-a]benzimidazole

Abstract

The thio-and selenocyanation of quinone monoimines of pyrido[1,2-a]benzimidazole series with the participation of dithiocyanogen and triselenodicyanide in mild reaction conditions results in formation of 9-or 6-thiocyano-and 9-selenocyano-derivatives in good yields.

Solvent-Controlled Synthesis of Thiocyanated Enaminones and 2-Aminothiazoles from Enaminones, KSCN, and NBS

“…These species have been employed in the synthesis of functionalized heterocycles and many sulfur-containing compounds, such as sulfonic acids, sulfonyl chlorides, thiols, thiocarbamates, sulfonyl cyanides, thioethers, disulfides, and phosphonothioates . As a result, the development of efficient approaches to construct C–SCN bonds has been studied intensively, and great progress had been made to synthesize organic thiocyanates . Quite recently, Wan group reported visible-light-induced thiocyanation of enaminones for the synthesis of thiocyanated alkene derivatives and chromones using NH 4 SCN as the thiocyano source under an aerobic atmosphere (Scheme a) .…”

Organic Selenocyanates: Rapid Advancements and Applicationsin the Field of Organic Chemistry

“…Triselenium dicyanide (TSD) or dicyanogen triselenide (Se(SeCN) 2 ) represents an alternative direct source of ideal selenocyanating reagent for the synthesis of aromatic and heteroaromatic selenocyanates, which has been well known for a long time [39a–c] . In particular, for the direct C−H bond, selenocyanation reactions that involve in situ generation of dicyanogen triselenide utilizing selenium dioxide (SeO 2 ) and malononitrile (CH 2 (CN) 2 ) have gained popularity because they are more economical and pragmatic, and in recent years, significant evolution has been ended in the synthesis of various types of selenocyanated molecules [39d–g] . Very recently, Maddani and coworkers established the first selenocyanation of ketene dithioacetals ( 102 / 102’ ) with SeO 2 and CH 2 (CN) 2 in situ generated triselenium dicyanide under transition metal free conditions [40] .…”

An Efficient Selectfluor-Mediated Oxidative Thio- and Selenocyanation of Diversely Substituted Indoles and Carbazoles

“…Aryl thio-and selenocyanates are versatile intermediates for various sulfur-and selenium-containing compounds that are of synthetic and biological interest [14][15][16][17][18][19][20][21][22][23][24][25][26]. Aryl thiocyanates are widely employed as building blocks in the synthesis of diverse sulfides [27,28], thiocarbamates [29], thionitriles [30], sulfonic acids [31], sulfonyl chlorides [32], thioesters [33], and sulfonyl cyanides [31] and mainly in the synthesis and functionalization of heterocyclic compounds [25,26,[34][35][36][37][38][39][40]. Particularly, selenium-containing organic compounds have recently attracted the interest of the scientific community due to their promising chemopreventive properties in connection with cancer therapy [32,[41][42][43][44], and also as antioxidant agents [45,46].…”

“…In particular, direct oxidative thiocyanation of C-H bonds have been achieved by using thiocyanate salts in the presence of oxidizing agents such as Mn(OAc) 3 [15], NCS [47], CAN [48], hypervalent iodine reagents [49], DDQ [50], oxone [51], oxygen [52], DEAD [53], and TBHP [22]. In comparison, direct selenocyanation approaches have not been reported under similar oxidative conditions [20][21][22][23][24][25][26]. Therefore, developing new and broad-based protocols for direct introduction of SCN and SeCN moieties into organic structures, in particular those motifs that are important for medicinal chemistry as building blocks of pharmaceuticals, continues to be relevant.…”