Selective and Efficient Oxidation of Sulfides and Thiols with Benzyltriphenylphosphonium Peroxymonosulfate in Aprotic Solvent

Abstract

Benzyltriphenylphosphonium peroxymonosulfate could be used for selective oxidation of aromatic and aliphatic sulfides and thiols to their corresponding sulfoxides and disulfides under nonaqueous and aprotic conditions without catalyst.

Some applications of zirconium(IV) tetrachloride (ZrCl4) and zirconium(IV) oxydichloride octahydrate (ZrOCl2.8H2O) as catalysts or reagents in organic synthesis

“…This transformation has been accomplished in a variety of ways [16][17][18][19][20][21][22][23][24][25][26][27][28]. During recent years, very useful procedures involving aqueous hydrogen peroxide (H 2 O 2 ) as the terminal oxidant, and a Lewis acid as an activator have been developed to promote this transformation [29], Very recently, H 2 O 2 /ZrCl 4 system has been applied as a selective method to oxidize sulfides efficiently to their sulfoxides or sulfones even in the presence of easily oxidized functional groups (Scheme 8) [30].…”

Heterocyclic bismuth(iii) compounds with transannular N→Bi interactions as catalysts for the oxidation of thiophenol to diphenyldisulfide

“…4 Various methods, including catalysis (homogeneous, 5 heterogeneous 6 or photo-catalysis 7 ), or noncatalytic oxidation procedures, e.g. with sodium periodate in a solid state reaction, 8 or benzyltriphenylphosphonium peroxymonosulfate under reflux in acetonitrile 9 , as well as electrochemical techniques 10 were employed (Table 1).…”

Metal-free oxidative dehydrogenation of imidazolines and pyrazolines using silica-adsorbed peroxymonosulfate under aprotic and almost neutral conditions

“…However, this reagent is insoluble in organic solvents and buffering is needed due to its acidity [38][39][40]. Recently, we reported benzyltriphenylphosphonium peroxymonosulfate (BTPPMS) as a mild, inexpensive, and efficient reagent in organic transformations [41][42][43][44]. Over the last two decades, the use of solid supports has become popular due to their characteristic properties such as enhanced selectivity and reactivity, straightforward work-up procedure, milder reaction conditions, and associated ease of manipulation [45].…”

“…Over the last two decades, the use of solid supports has become popular due to their characteristic properties such as enhanced selectivity and reactivity, straightforward work-up procedure, milder reaction conditions, and associated ease of manipulation [45]. Following our continued interest in BTPPMS [41][42][43][44] and in the course of our studies on the dehydro-genation of organic compounds [43], we herein report metal-free oxidative dehydrogenation of 1,3,5-tri-substituted pyrazolines 1 and 2-substituted imidazolines 3 to their corresponding pyrazoles 2 and imidazoles 4 employing BTPPMS as an oxidant silica-adsorbed as the supporting agent under non-aqueous and almost neutral conditions. To the best of our knowledge, this is the first example of BTPPMS-mediated metal-free dehydrogenation of pyrazolines and imidazolines.…”

“…That is, the treatment of 1,3,5-triphenyl-pyrazoline 1a as a model compound (1 mmol) with BTPPMS (2 mmol) silica-adsorbed (0.5 g per mmol of pyrazoline) as an inexpensive and readily available supporting agent in refluxing acetonitrile for 5 h afforded 1,3,5-triphenylpyrazole 2a in 76% yield. The oxidation of compound 1a was investigated with BTPPMS alone in refluxing acetonitrile and only 30% of compound 2a was obtained from the reaction mixture after 5 h. The reactions in MeCN, which turned out to be one of the best choices in our previously organic transformations [41][42][43][44], produced the corresponding pyrazoles 2 by simple filtration and evaporation of the solvent in good to moderate yields. The results and reaction conditions are exemplified in Table 1.…”