NH₄I-Promoted and H₂O-Controlled Intermolecular Bis-sulfenylation and Hydroxysulfenylation of Alkenes via a Radical Process

Abstract

An NH4I-promoted and H2O-controlled intermolecular difunctionalization of alkenes for the synthesis of bis-methylsulfane and β-hydroxysulfides is presented. Mechanistic investigation revealed the reaction proceeds via methylthiyl radical addition to CC of alkenes to give a carbon-centered radical and immediately cyclize to a thiiranium ion, followed by combination with H2O to afford β-hydroxysulfides in 52–89% yields with chemo- and regioselectivities. In the absence of water, 1,2-disulfenylation takes place to give bis-methylsulfane in moderate to good yields.

Metal-Free Oxidative Esterification of Ketones and Potassium Xanthates: Selective Synthesis of α-Ketoesters and Esters

“…Iodine radicals can react with methanthiol to liberate CH 3 S • radicals (Scheme , eqs 1 and 2). The methylthiyl radical (CH 3 S • ) selectively adds to the CC double bond of A from enol isomerism of acetophenone to form intermediate B , which undergoes further single-electron oxidation to afford a MeS-substituted carbocation C and produces thioether products 6 . On the other hand, the oxidation of potassium xanthates by I 2 gives xanthogen disulfides.…”

Intermolecular difunctionalization of alkenes: synthesis of β-hydroxy sulfides

“…Recently, Li and Chen described a unique NH 4 I-promoted hydroxymethylthiolation of various terminal alkenes 16 using DMSO as an easy-handling methanesulfenyl source and water as an oxygen source. 19 The reaction was carried out in a 1 : 1 mixture of DMSO and H 2 O under additive-free conditions and afforded the desired hydroxysulfenylation products 17 in moderate to high yields and outstanding regioselectivities ( Scheme 8a ). Although the reaction tolerated various functional groups, the need for elevated temperature (130 °C) may limit its range of application.…”

Recent Advances in Synthetic Strategies to 2,3-Dihydrobenzofurans

“…Application of this reaction to o-allylphenols using NH 4 I in presence of dimethyl sulfoxide gave a small number of 2-[(methylthio)methyl]-DHBs in excellent yields (72-92%) (Scheme 25). 88…”