Carbothiolation Reactions

Meerwein type arylations involving radical additions to carbon-heteroatom multiple bonds such as in isothiocyanates have been further extended to tandem reactions leading to heterocycles [117, 118]. 

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A number of sulfur-centered radical scavengers have been employed for Meerwein type carbothiolation reactions [109, 110]. The most prominent of those are certainly xanthates [111-113] and thiocyanates, among which the latter have received special attention recently. As shown in Scheme 21, thiocyanates are well-suited for the functionalization of activated and non-activated alkenes [114, 115]. Remarkably, the reaction of 56 with 2-methallyl chloride to give 57 is not significantly impeded by the possible (3-fragmentation of a chlorine radical, which would lead to allylation products [116]. With an activated and a non-activated alkene present in a substrate... 

The reaction of 1-amino-l-deoxy-D-fructose with ethyl thiolacetoacetate under the same conditions gives a mixture of ethyl 2-methyl-4-(D-ara6ino-tetrahydroxybutyl)pyrrole-3-carbothiolate (18), a lactone [tentatively considered to be the 7-lactone (27) of 2-methyl-4-(D-aroWno-tetrahydroxy-butyl)pyrrole-3-carboxylic acid (19)], and a small proportion of a com-... 

They also extend their reaction to the carboselenation of alkynes with selenol esters under similar conditions employed for the carbothiolation (Eq. 33) [66]. 

Carbothiolation affords an opportunity to install C-C and C-S bonds in a single reaction, thereby rapidly generating molecular complexity. This process is... 

Nakamura and coworkers reported an intramolecular carbothiolation of allq nes catalysed by gold(i) chloride at room temperature. The protocol allowed for the synthesis of 2,3-disubstituted benzothiophenes in short reaction times, with excellent yields when 2 mol% of the catalyst was used (Scheme 16.62). 

Brpnsted acids have shown good-to-excellent levels of selectivity in C S bond formations. This chapter aims to review the stereoselectivity aspect of C—S bond formations that use commodity chemicals such as alkynes, alkenes, and alkanes. The stereoselective functionalization of alkynes is reviewed in section 1 using hydrothiolation, bisthiolation, and carbothiolation that necessitate transition metal and Brpnsted acid catalysis. The next section covers sulfethera-tion and conjugate addition reactions, where electron-rich and electron-poor alkenes are exploited under Lewis acid and Brpnsted acid catalysis. The last section is centered on the use of alkanes in the stereoselective 5-alkylation catalyzed by transition metal and organocatalysis. 

The introduction of sulfur moieties to unsaturated hydrocarbon compounds is an important synthetic strategy in the preparation of bioactive compounds. In particular, the use of alkynes enables the facile synthesis of alkenyl sulfides that are stereochemically as well as regiochemically defined structures. Given the important role of catalysts in the stereospecific addition of sulfur-containing reagents to alkynes, the following four sections are devoted to hydrothiolation, bisthiolation, carbothiolation, and related reactions. 

Kuniyasu H, Kurosawa H (2002) Transition-metal-catalyzed carbon-heteroatom three-component cross-coupling reactions a new concept for carbothiolation of alkynes. Chem Eur J 8 2660-2665... 

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