Cleavage of C-S bonds

The cleavage of C—S bonds in C—SO2R anion radicals plays an important role in SrnI tyP processes ". Kornblum and coworkers described a photostimulated electron transfer chain substitution at a saturated carbon where the leaving group is PhSOj ... 

Kilbane n, J. J., Process for enzymatic cleavage of C-S bonds and process for reducing the sulfur content of sulfur-containing organic carbonaceous material. Patent No. US5344778. 1994, Sep. 06. 

These two strains, B. sphaericus strain ATCC 53969 and R. rhodochrous strain ATCC 53968 discovered by Kilbane as being capable of dibenzothiophene desulfurization were patented as two separate (European) patents [67,91], respectively. These two patents issued by 1991 also described the use of the enzymes derived from these organisms and their cell-free extracts for desulfurization applications. Both strains were reported to carry out selective cleavage of C—S bonds in organic carbonaceous materials. The organism, Bacillus sphaericus strain ATCC 53969, was, however, reported in Exxon patents, to be capable of C—C bond cleavage as well and therefore its ability to perform desulfurization without loss of fuel value is questionable. 

Cyclobutane (35) and its analogs were not described in literature so far. They can be regarded as an easy source both of a cyclobutyl radical [239] (by cleavage of C—S bond under electron transfer) and a dienophile [240]. Thus, (35) readily yields the corresponding cyclobutene (36) in the presence of electrogenerated bases (EGB)... 

Other examples of the reductive cleavage of C-S bonds are given in Table 8. 

Radical reductions with [(CH ) Si]3SiH.1 In combination with an initiator, this silane (I) reduces not only alkyl halides, but also thionoesters (used for deoxygenation of secondary alcohols) and selenides. However, cleavage of C-S bonds is inefli-... 

The cleavage of C—S bonds in [M(S )] complexes usually concerns S C(alkyl) bonds and is an unwelcome reaction in most cases. This unwanted... 

Summary Mono-, bis-, tris-, and tetrakis(lithiomethyl)silanes were prepared by reductive cleavage of C-S bonds with lithium naphthalenide (LiCioHg) or lithium p,p -di-rbutylbiphenylide (LiDBB) and characterized by the reaction with Bu3SnCl. The poly(lithiomethyl)silanes can be used as new building blocks for in a-position substituted silanes or, for example, silacyclobutanes. 

For the synthesis of the known two poly(lithiomethyl)silanes the halogen-lithium exchange (for 1 [2]) and the reductive cleavage of C-S bonds with lithium (for 3 [3]) were used [4] (Scheme 1). 

We tried to synthesize the carbon analogs of 14 and 12 by reductive cleavage of C-S bonds. The isolated products indicate, that 50 % of the C-S bonds were cleaved by electron transfer reactions and 50 % by LiSPh-elimination, probably after a H,Li-exchange (Scheme 6). 

An application of the synthetic concept to carbon analogs is not possible. LiSPh-elimination and/or LiSPh-elimination after previous H,Li exchange occurred for alkyllithium-intermediates formed by reductive cleavage of C-S bonds. Reaction of this type have been observed for similar compounds [7]. The silicon atom obviously plays a central role in the reactivity of the presented structure types. 

Further related work including investigations of the reductive cleavage of C-S bonds for the synthesis of other compounds with the structure element "Li-CR2-El-CR2-Li" (El = element of group 14-16, partly with substituents R = H, alkyl, aryl) is in progress. 

SET cleavage of C—S bonds is accompanied by eliminations (which are often the only reactions observed) when a good leaving group is present at the vicinal position (Scheme 10). 

Selective introduction of a fluorine atom into organic compounds is important due to the unique biological and physical properties of fluorinated compounds. One useful method for C-F bond formation is desulfurative fluorina-tion realized by a cleavage of C-S bonds of dithioacetals. Thus, 1,3-ditholane derivatives undergo a facile reaction... 

Anodic Deprotection of the Carbonyl Group Cleavage of C—S Bonds 349... 

The promotion effect of the CoMoS site appears to occur through increased hydrogen activation, which facilitates removal of sulfur atoms after cleavage of C-S bonds on exposed molybdenum ions/ Cobalt incorporated into the support may also act as a structural promoter by enhancing dispersion of the sulfided species. ... 

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