Sulfur and Related Elements -X Activation

The progress on S-C bond activation, which covers the reduction of a C-S bond to a C-H bond, cross coupling reaction of sulfides with main group organometaUic nucleophiles, ring opening reactions of thietanes and thiiranes, and desulfurization of thiols, sulfides, and thiophenes has already been reviewed elsewhere [6-10], and 

Pioneering work involving the combinahon of an organosulfide, a C-C unsaturated organic compound and a transihon metal catalyst was reported by Reppe in 1953, in which Ni(CO)4-catalyzed hydrothiocarboxylahori of alkyne or ethylene by thiol and CO was briefly described to give the corresponding thioesters 1 or 2 (an application of one of the so-called Reppe reachons) (Eqs. 7.1 and 7.2) [12, 13]. 

Although these reactions indicated the great potenhal of transihon metal-catalyzed reachons of organosulfides with C-C unsaturated organic compounds, little attenhon has been paid to such a combination of reactions for many years since then. In 1960, Holmquist and Carnaham reported the Co-catalyzed reachon of thiol with CO (1000 atm) at 250-300°C to afford thioester 3 in up to 46% yield with ca. 1-5 wt% of catalyst (Eq. 7.3) [14]. 

When the reachon was carried out using 1,3-butanedithiol, thiolactone 4 or 5 was produced (Eq. 7.4). (The product was not specified in the paper.) In 1973, the hydro thiocarboxylahon catalyzed by palladium catalyst was reported in a US Patent (Eq. 7.5) [15]. 

Unlike the case of the Ni-catalyzed reaction, which afforded the branched thioester (Eq. 7.1), the PdCl2(PPh3)3/SnCl2-catalyzed reaction with 1-alkyne and 1-alkene predominantly provided terminal thioester 6 in up to 61% yield in preference to 7. In 1983, a similar hydrothiocarboxylation of an alkene was also documented by using a Pd(OAc)2/P( -Pr)3 catalyst system with t-BuSH to form 8 in up to 79% yield (Eq. 7.6) [16]. It was mentioned in the patent that the Pt-complex also possessed catalyhc activity for the transformation, although the yield of product was unsatisfactory. In 1984, the hydrothiocarboxylation of a 1,3-diene catalyzed by Co2(CO)g in pyridine was also reported in a patent [17]. In 1986, Alper et al. reported that a similar transformation to the one shown in Eq. (7.3) can be realized under much milder reaction conditions in the presence of a 1,3-diene [18], and the carboxylic ester 10 was produced using an aqueous alcohol as solvent (Eq. 7.7) [19]. 

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Kuniyasu H (2001) Sulfur (and related elements)-X activation. In Togni A, Giiitzmacher H (eds) Catalytic heterofunctionalization. Wiley-VCH, Ziirich... 

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