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This manuscript reports a novel method for the direct iodination of the C‐4 pyrazole ring generated in situ by the reaction of 1,1,3,3‐tetramethoxypropane and various hydrazines. In this approach, potassium iodate (KIO3) is used as the iodinating agent and (PhSe)2 is used as catalysts under acidic conditions. This protocol provides a convenient method for the efficient synthesis of 4‐iodo‐1‐aryl‐1H‐pyrazoles, valuable intermediates for several different coupling reactions. [ABSTRACT FROM AUTHOR]

Ammonium persulfate is a mild oxidant capable of oxidizing the selenium-selenium bond through thermal activation or under drastic acid catalysis. In this paper we highlight that this reaction can be activated photochemically, starting from diphenyl diselenide in the absence of any organic or and/or metallic photocatalyst or additive. The protocol was applied to a well-known panel of selenoalkoxylation reactions and the obtained results clearly indicate the involvement of an electrophilic selenium reagent. [ABSTRACT FROM AUTHOR]

In the recent three decades, a steadily growing interest in the use of ball milling in organic synthesis has developed. The purpose of this mini-review is to briefly present protocols showing the use of ball milling in the formation and transformation of sulfur-containing functional groups. First, mechanochemical functionalization of sulfur-containing compounds is discussed. The second part devoted to interconversions of sulfur-containing functional groups in mechanochemical conditions summarizes the results on sulfenylation reactions, coupling reactions, redox reactions and condensation reactions. We hope that this review will be a useful addition to the collection of review publications devoted to mechanochemistry and will attract the attention of a wider group of researchers dealing with organosulfur chemistry by drawing attention to the attractive features of mechanochemical protocols. [ABSTRACT FROM AUTHOR]

Two selanyl compounds, 5-(phenylselanyl)pentanoic acid (1) and 5-(benzylselanyl)pentanoic acid (2), were investigated for their reactivity towards one-electron oxidants, particularly the radiolytically generated hydroxyl radical (˙OH). The reactions of compounds 1 and 2 with ˙OH led to the formation of transient absorptions, characterized by peak wavelengths (λmax) at 630 nm and 560 nm, respectively. Concentration-dependent absorption studies revealed that the transient from 1 with λmax of 630 nm corresponds to a dimer species featuring a two-centre–three-electron (2c–3e) bond. Conversely, the species exhibiting λmax of 560 nm for 2 was identified as a monomer radical cation. To validate the identities of these transients, compounds 1 and 2 underwent reactions with specific one-electron oxidants, namely the dibromide radical (Br2˙−) and carbonate radical anion (CO3˙−). The differences in the reactivities of the transients derived from compounds 1 and 2 were distinguished by measuring their ability to oxidize glutathione, a biologically important thiol. Interestingly, the transient from compound 2 exhibited a relatively lower oxidizing ability than the transient from compound 1. Compound 2 also demonstrated higher scavenging rate constants in reactions with Br2˙−, CO3˙−, and peroxyl radicals (derived from thermal degradation of 2,2′-azobis(2-amidinopropane) hydrochloride, AAPH). Computational calculations were carried out employing the M05-2X/6-311+G(d,p)/SMD method to offer additional proof in favor of dimer radical species during the interactions of compound 1 with ˙OH. The calculations revealed a competitive formation of both σ- and π-type dimer radicals from compound 1. However, the experimental spectrum primarily corresponded to the σ-type dimer, as indicated by the predicted λmax (630 nm) using the TDDFT method. This study shows that the benzyl-containing selanyl system is a better free radical scavenger than the phenyl-containing selanyl system, highlighting its potential as a potent free radical scavenger. [ABSTRACT FROM AUTHOR]