Regioselective thiocyanation of aromatic and heteroaromatic compounds using ammonium thiocyanate and oxone

Thiocyanation of BODIPY dyes and their conversion to thioalkylated derivatives

“…Additionally, oxone is known to lead to the formation of the hypothiocyanate anion (OSCN) -1 and hypothiocyanous acid (HOSCN), which might also be electrophilic intermediates in this reaction (Scheme 1). Alternatively, a radical mechanism has been proposed and considered for similar reactions 20,22 . In this case, the BODIPY itself would be oxidized to a radical cation intermediate and stabilized by the tertiary carbons.…”

Simple and Highly Efficient Catalytic Thiocyanation of Aromatic Compounds in Aqueous Media

“…On the other hand, the nucleophilic attack of thiocyanate ion at an aromatic nucleus via displacement reactions is not an easy way to form thiocyanated compounds [2 -5]. So, several methods have been developed for the electrophilic thiocyanation of arenes [6] [7] such as bromine/potassium thiocyanate [8], N-thiocyanatosuccinimide [9], an thiocyanate salt in the presence of ceric ammonium nitrate (CAN) [10], acidic montmorillonite K10 clay [11], I 2 /MeOH [2], Oxone [12], pentavalent iodine, i.e., 2-iodoxybenzoic acid (IBX) [13], or potassium peroxydisulfate/copper(II) sulfate [14]. However, these methodologies suffer from one or more drawbacks such as the use of toxic transition metals as oxidants [1], the toxicity of reagents in general [7] [8], large excess of catalyst [11], and performances under certain special conditions.…”

Green Thiocyanation of Aromatic and Heteroaromatic Compounds by Using Silica Boron Sulfonic Acid as a New Catalyst and H<SUB>2</SUB>O<SUB>2</SUB> as Mild Oxidant

“…The addition was highly regioselective occurring at the 3-position of the indole ring. 19,37 Various N,N-disubstituted aromatic amines were converted into the respective 4-thiocyanato amine in high to excellent overall yields ( Table 2, entries 5-10). The reactions were clean and the products were obtained with high para-selectivity (Table 2, entry 9, 10).…”

“…Several methods have been developed for the thiocyanation of arenes by using various reagents under certain conditions [9][10][11][12][13][14][15][16][17][18]. Yet, only a limited number of reagents, such as bromine/potassium thiocyanate (only for indoles) [15], N-thiocyanatosuccinimide (only for 5-methoxy-2-methylindole and accompanied by two bisthiocyanates) [16], ceric ammonium nitrate (CAN) [17], acidic mont K10 clay [18], iodine/methanol, oxone [19], diethyl azodicarboxylate [20], IL-OPPh2 [21], potassium peroxydisulfate-copper(II) [22], have been applied to the thiocyanation of aromatic and heteroaromatic systems. However, these methodologies suffer from one or more drawbacks such as the less availability or hard preparation of starting materials [15][16], the requirement for a large excess of strong oxidizing reagents, low yields for some compounds [17], and performances under certain special conditions [18].…”