C-S bond, cleavage

Ring opening of the heteroring (C—S bond cleavage), 300, or even ring opening with elimination of the heteroatom, 301 and 302, happens in the reaction of benzothiophene with Ru3(CO)l2 (94AGE1381). 

It was reported earlier that even dialkyl sulphides are efficiently oxidized to sulphoxides without a concomitant C—S bond cleavage by NBS or N-chlorosuccinimide (NCS) when the reaction is performed in anhydrous methanol at low temperature103. iV-Chloro-Nylon-6,6 in methanol-water or dioxane-water104 and iV-bromo- -caprolactam in water or alcohols105 were also used successfully for oxidation of sulphides. 

Sulphides are quickly and efficiently converted into sulphoxides by 1-chlorobenzo-triazole (NCBT) in methanol at —78°106. However, this. reagent cannot be used for the oxidation of t-butyl sulphide and dibenzyl sulphide since C—S bond cleavage takes place. 

The reaction of dimethyl sulphoxide with t-butyl hypochlorite initially yields trichl-oromethyl methyl sulphone but further reactions, involving C—S bond cleavage, occur on prolonged contact of the two reagents98 99. 

At this point, special mention37 should be made of the behaviour of highly conjugated ethylenic sulphones in weakly acidic media. For example, in the case when R1 =Ph (Z isomer), a fairly stable anion radical was obtained in dry DMF. However, either in aprotic (consecutive two one-electron transfer) or in protic media (ECE process, occurrence of the protonation step on anion radical), C—S bond cleavage is observed. The formation of the corresponding olefins by C—S bond cleavage may occur in high yield, and is nearly quantitative when R1 = H and R2 = Ph for an electrolysis conducted in... 

Curiously, this phenomenon is not observed for (CH3)2SO under thesameconditions28. On the other hand, solutions of (CH3)2SO or (CD3)2SO in CD3OD gave normal CH3 and CD3 radicals28 corresponding to a C—S bond cleavage following electron capture. 

Subsequently, Paquette and Johnson used LAH reductions to convert strained thietane or thiolane derivatives to their respective sulphides, generally in good yields. Whitney and Cram described the LAH reduction of a chiral derivative of benzothiophene sulphone, as outlined in equation (24). The authors also noted the formation of hydrogen gas and suggested that their results were consistent with those of Bordwell as outlined in equation (22), namely that reduction takes place by the formation of an aluminium oxide and hydrogen gas. In this case, the reduction clearly cannot involve the formation of an a-sulphonyl carbanion and it is unlikely that any C—S bond cleavage and reformation could have occurred. 

By oxidative addition of aryl sulphides to low-valent nickel complexes, a C—S bond cleavage occurs to form Ni11 thiolate complexes. For example, exposure of diaryl sulphides to [(But3P)3Ni0] leads to oxidative addition, with nickel inserting into the C—S bond (280).814... 

A nickel-promoted C—S bond cleavage has been reported,860 which occurs when solutions of the Ni1 complex of (330) are electrogenerated. The product was identified by cyclic voltammetry and spectroscopy as [Ni(C6H4S2)2]2. EPR and NMR evidence suggests a one-electron mechanism, involving reduction to a 19-electron Ni1 species, electron transfer, and concomitant C—S bond cleavage, extrusion of ethylene followed by a further one-electron reduction and extrusion of ethylene sulfide. 

Other claimed matter DBT for enrichment, biocatalyst preparation contacting process Enzymes contacting process Pure compounds as feedstock Membrane fragments and extracts Cell-free extract (envelope and its fragments + associated enzyme) reversible emulsion microemulsion reverse micelles Cell-free enzyme preparation microemulsified process RR and derivatives and other biocatalyst concepts + any known microorganism active for C—S bond cleavage... 

Toutchkine, A., Aebisher, D. and Clennan, E.L. (2001). Substituent dictated partitioning of intermediates on the sulfide singlet oxygen reaction surface. A new mechanism for oxidative C-S bond cleavage in a-hydroperoxysulfides. J. Am. Chem. Soc. 123, 4966 4973... 

Generation of Alkoxycarbenium Ion Pools by Oxidative C-S Bond Cleavage... 

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