Transition-Metal-Free Iodine Catalyzed Selenocayanation of Styrenyl Bromides and an Easy Access to Benzoselenophenes via Intermediacy of Styrenyl Selenocyanate

Abstract

A convenient procedure has been developed for the synthesis of styrenyl selenocyanates and benzoselenophenes from readily available styrenyl bromides by reaction with potassium selenocyanate in the presence of iodine under specified conditions. A series of both compounds have been obtained by this procedure. The synthesis of styrenyl selenocyanates has not been previously reported, and thus this method is of much significance.

C4‐Selective Synthesis of Vinyl Thiocyanates and Selenocyanates Through 3,4‐Dihalo‐2(5H)‐furanones

“…However, compared with the synthesis of vinyl thiocyanate derivatives, the construction of vinyl selenocyanate derivatives is rare,[11d] even recently a three‐component reaction method based on activated alkyne has recently been successfully developed . In other reports, it is usually necessary for common vinyl bromide substrates to use I 2 as catalyst (Scheme a ), Otherwise, it is necessary to use organometallic compounds as starting materials (Scheme b ) . Even so, sometimes it takes a two‐step reaction to get the target product (Scheme c ) .…”

Recent Advances in the Synthesis of Selenophenes and Their Derivatives

“…The optimal conditions were used in the synthesis of the BTBS material OFET 123m (53% yield); however, using 2 equivalents of base at 100 °C (Scheme 83). In 2017, the I 2 -catalyzed selenocyanation of styryl bromides 124 with potassium selenocyanate, affording benzo[b]selenophenes 125 was described [173]. The best conditions for the annulation reaction was found as the stirring a mixture of the bromide 124 and KSeCN (1.2 equiv) in the presence of I 2 (20 mol%) and DMSO as the solvent at 110 • C, under an argon atmosphere, for 48 h. Under these conditions, a total of twenty-six examples of benzoselenophenes 125 were prepared in moderate to excellent yields (45-95%).…”

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].…”

“…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.…”