Sulfonium compound

Sulfonium Compounds. Sulfonium compounds of the type R R R S X are named by citing in alphabetical order the radical names followed by -sulfonium and the name of the anion. For heterocyclic compounds, -ium is added to the name of the ring system. Replacement of > CH by sulfonium sulfur is denoted by the prefix thionia-, and the name of the anion is added at the end. 

The reaction of thioethers with ethyleneimine in the presence of acid yields sulfonium compounds. The reaction is reversible under alkaline conditions (125). Compounds in which double-bonded sulfur can exist in tautomerism with a form having a free SH group, such as thiourea (126,127), thiocarboxyhc acids (128), and thiophosphates (129), react to give aminoaLkylated products. The P-aminoethyl thiocarboxylate rearranges to give the amide. 

Sulfonium compounds (—C— SR2) undergo elimination similar to that of their ammonium counterparts (17-6 and 17-7) in scope and mechanism but this reaction is not of great synthetic importance. These syn-elimination reactions are related to the Cope elimination (17-8) and the Hofmann elimination (17-6). ... 

Certain alkylated ammonium, phosphonium, or sulfonium compounds are effective, in relatively low concentrations, in interfering with the growth of gas hydrate crystals [972] and therefore are useful in inhibiting plugging by gas hydrates in conduits containing low-boiling hydrocarbons and water. For example, tetrabutylammonium bromide will be active. Gas hydrate or ice formation is further inhibited in lines by adding amino acids or amino alcohols [523]. 

In addition the structure of the 1,2-azathiabenzene 78 was also confirmed by chemical evidence as shown in Scheme 10. Protonation of 78a (R1 = R2 = Me) with 70% perchloric acid yielded the corresponding cyclic amino sulfonium salt 82a in 87% yield, but not the starting sulfonium compound 76a, suggesting predominance of sulfilimine structure 78a rather than cyclic sulfonium ylide stmcture 80a. Thus, compound 78 could be recognized as the first example of a 1,2-azathiabenzene having sulfur at a bridgehead position. A proposed mechanism for the formation of 78 and 79 is shown in Scheme 9. The most acidic proton adjacent to sulfur in 76 is deprotonated with... 

R.P. Kiene, P.T. Visscher, M.D. Keller and G.O. Kirst (eds), Biological and Environmental Chemistry of DMSP and Related Sulfonium Compounds, Plenum Press, New York, 1996. 

Hatton A, Darroch L, Malin G (2004) The role of dimethylsulphoxide in the marine biogeochemi-cal cycle of dimethylsulphide. Oceanogr Mar Biol Ann Rev 42 29-56 Hatton A, Malin G, Turner S, Liss P (1996) DMSO a significant compound in the biogeochemical cycle ofDMS. In Kiene RP, Visscher P, Keller M, Kirst GO (eds) Biological and environmental chemistry of DMSP and related sulfonium compounds. Plenum, New York, pp 405—413... 

Hunt, R. and Renshaw, R.R. (1925) Some effects of arsonium, stibonium, phosphonium and sulfonium compounds on the autonomic nervous system./. Pharmacol., 25, 315—353. 

Cleavage of Sulfonium Compounds Hydro-dialkylsulfonio-elimination... 

Cleavage of sulfonium compounds 8 22 Rearrangement of sulfonium salts... 

Sulfonium compounds occur in a wide range of unicellular algae as well as red algae. They have been shown to be the major source of atmospheric sulfur compounds such as dimethyl sulfide and from methanethiol from the ocean, which has a central role ir he global sulfur cycle [143]. 

Cullen et al. (1994) have proposed a possible mechanism of arsenic methylation after the study in which arsenite, arsenate, monomethyl-arsonate or dimethylarsinic acid were added to the growth medium in the presence of the unicellular alga Polyphsa peniculus. Evidence of arsenic biomethylation by the micro-organism Apiotrichum humicola in the presence of L-methionine-methyl-d3 has come from the same laboratory (Cullen et al., 1995). Their findings point to the role of S-adenosylmethionine, or a related sulfonium compound as possible methyl donors. Arsenic biomethylation and biotransformation has also been demonstrated in a freshwater environment (Kuroiwa et al., 1994). 

The simplest sulfur ylids are formed from sulfonium salts 69 by deprotonation in base. These ylids react with carbonyl compounds to give epoxides.18 Nucleophilic attack on the carbonyl group 70 is followed by elimination 71 of dimethylsulfide 72 and formation of the epoxide 73. You should compare diagram 71 with diagram 23 in chapter 15. The phosphonium ylid reacted by formation of a P-0 bond and an alkene in the Wittig reaction. The sulfonium compound reacts by formation of a C-O bond 71 as the S-O bond is much weaker than the P-0 bond. The sulfonium salt 69 can be reformed by reaction of 72 with Mel. 

Deprotonation of 2-alkyl-3-aroyl-l/7-2-benzothiopyranium salts by triethylamine generates an ylidic 2-thianaphthalene which is resonance stabilized by the 3-aroyl group. Behaving as an tf-qui nodi methane, a cycloaddition with unchanged thiopyranium salt follows and a complex benzothiopyran is formed via the sulfonium compound 304 (Scheme 48) <1996CC1659>. 

An interesting example of oxygen activation by onium salts of nontransition elements has been claimed. Sulfonium salts were found to be especially effective,211 and it was proposed212-214b that dioxygen complexes of sulfonium compounds can initiate autoxidations via hydrogen transfer with hydrocarbons, e.g.,... 

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