Chloro sulfonium salts

Lactam sulfonium salts bearing a dihydrothiopyran skeleton with a sulfonio bridgehead have been synthesized. Tricyclic benzothiazinium salts 87 were prepared by [4+2+]-polar cycloaddition of a thionium intermediate 99, generated from the corresponding a-chloro sulfide 98, in the presence of silver perchlorate in moderate to good yields (see Equation (28) and Table 17) <1997J(P1)309>. Cycloaddition with isoprene 41b gave adducts 87b and 87c as a... 

Placing anion stabilizing groups on the cyclopropane greatly facilitates generation of cyclopropyl nucleophiles. The diphenylsulfonium ylide has proven to be an exceptionally versatile conjunctive reagent25). The sulfonium salt 9, available from either 3-chloro-l-iodopropane (Eq. 24a) or 3-chloro-l-propanol (Eq. 24b), is a nicely crystalline stable salt that can be stored indefinitely26,Z7). While substituted... 

Sulfonium, cyclopropyldiphenyl tetrafluoroborate, 54, 28 Sulfonium salts, acetylenic, furans from, 53, 3 Sulfonium ylides, 54, 32 Sulfur, reaction with organo-lithium compounds, 50, 105 Sulfuryl chloride, with 1,1-cyclobutanedicarboxylic acid to give 3-chloro-l,1-cyclobutanedicarboxylic acid, 51, 73... 

Dibromomethylsulfonium salts [CH3SBr2 ][A ] (313) and dimethyl-iodosulfonium salts [(CH3)2SI ][A ] (312) with A = AsFe , SbCle were synthesized via halogen exchange from the corresponding chloro-sulfonium analogues with HBr or HI in liquid SO2, or by the reactions... 

Both the H chemical shifts and NOE data suggest that chloro-A -sulfanes and sulfonium salts 24 and 25 having an o-MeO, o-Cl, or o-Me substituent on the aryl ring assume a skew conformation, whereas the aryl ring in compounds without an ortV o-substituent can rotate practically freely about the S-C(l ) axis. H and N NMR examinations of diaryl(acylamino)(chloro)-A -sulfanes 24a-e showed that they exist only in CDCI3 and dimethyl sulfoxide-t4 (DMSO- 6) solvents (Equation 3), whereas in MeOD complete ionic dissociation takes place, leading to the sulfonium chloride (see Table 5) <2001J(P2)339>. 

NMR can be used for the characterization of axial hypervalent S-Cl bond and S- O close contact in chloro-A -sulfanes and sulfonium salts 24-26 with or7,4o-substitution in the aromatic ring. The solvent effect has also been investigated CDCI3 is the most favorable for stabilizing the hypervalent S-Cl bond (see Table 5) <2001J(P2)339>. 

Treatment of the 6 -chloro sulfurane 37 with AgBF4 resulted in removal of the chlorine atom to afford the sulfonium salt 21 in 96% yield <1998JOC5265>. 

The rate was retarded by added chloride ion (common-ion effect) but no 3-chloro-thietane was identified among the products. No reaction occurred in the absence of acetate. The possible intermediacy of a sulfurane, proposed in reactions of epi-sulfonium salts/ was not considered. 

Some of the reactions of coordinated donor atoms are quite unexpected. Thus, coordinated thiol will react with alkyl bromides to form sulfonium salts. Here, there are lone pairs on the donor atom in addition to the one involved in forming the coordinate bond. Their qualitative reactivity is hardly affected by coordination. Ammonia which has been coordinated to platinum (IV) will form iV-chloro derivatives when treated with hypochlorite. This reaction involves an N-H bond rather than the lone pair. Coordinated PCI3 will undergo hydrolysis to give coordinated P(0H)3, a reaction which involves the P-Cl bonds rather than the lone pair. 

The proof given in support of dianion formation does not however seem to be sufficients Nevertheless the single step process is reasonably efficient when primary alkyl halides are used but none of the dialkylated compound is produced with isopropyl iodide and benzyl bromide. 2-(o>-Haloalkyl)-l,3-di-thianes have proved to be valuable precursors of 1,3-dithianes derived from cyclic ketoncs. Haloge-nated 1,3-dithianes have been in turn prepared from 2-lithio-l,3-dithiane and stoichiometric amounts of u-chloro- or bromo-alkyl iodides or with an excess of the corresponding dichloride (Scheme 64, entry c). Use of u-bromoalkyldithianes is often impractical because of the ease with which these compounds are transformed into cyclic sulfonium salts. ... 

Chloro(dimethyl)sulfonium salts are readily formed in 92% yield by the action of chlorine on the dimethyl sulfide-antimony chloride adduct627 in methylene dichloride solution ... 

Chloro(dimethyl)sulfonium salts are extremely reactive, usually losing the chlorine as anion and thus able to transfer the dimethylsulfonium group readily to nucleophilic compounds such as alcohols, compounds containing acidic CH groups, organic sulfides, and disulfides.627... 

Deprotonation of the sulfonium salt and addition to the less-hindered face of the ketone gives the intermediate alkoxide, which cyclizes to the epoxide. Ring-opening of the epoxide with chloride (inversion of configuration) gives the chloro-aldehyde 3. See K. Sato, T. Sekiguchi and S. Akai, Tetrahedron Lett., 42 (2001), 3625. 

Reaction of l-chloro-l-(phenylthio)alkanes with sodium dicarbonyl(cyclopenta-dienyl)ferrate provides (a-phenylthio)alkyliron complexes. If these complexes have a double bond in their side chain in an appropriate distance to the iron center, methylation of the thioether results in an intramolecular cyclopropanation via the corresponding sulfonium salt and the (alkylidene)iron complex as intermediates (Scheme 4—63). ... 

Methods for the preparation of tritiated methyl iodide in the laboratory use variations of the sp tritiodehalogenation approach. Palladium-catalyzed tritiodechlorinations of chloro-methyl ester 113 and of chloromethyl sulfide 115 ° have been developed as less hazardous alternatives to the older laboratory procedure for C HH2l at 15-22 Ci/mmol starting from bis(chloromethyl)ether °. The initially formed nonvolatile monotritiated 114 and 116 can be conveniently isolated, purified and finally subjected to ester cleavage with either lithium iodide or hydriodic acid, or, in the second case, by thermolysis of the intermediately generated sulfonium salt 117. 

Electrophilic attack on the sulfur atom of thiiranes by alkyl halides does not give thiiranium salts but rather products derived from attack of the halide ion on the intermediate cyclic salt (B-81MI50602). Treatment of a s-2,3-dimethylthiirane with methyl iodide yields cis-2-butene by two possible mechanisms (Scheme 31). A stereoselective isomerization of alkenes is accomplished by conversion to a thiirane of opposite stereochemistry followed by desulfurization by methyl iodide (75TL2709). Treatment of thiiranes with alkyl chlorides and bromides gives 2-chloro- or 2-bromo-ethyl sulfides (Scheme 32). Intramolecular alkylation of the sulfur atom of a thiirane may occur if the geometry is favorable the intermediate sulfonium ions are unstable to nucleophilic attack and rearrangement may occur (Scheme 33). 

Quaternary ammonium alkyl ethers are prepared similarly an alkaline starch is reacted with a quaternary ammonium salt containing a 3-chloro-2-hydroxypropyl or 2,3-epoxypropyl radical. Alternatively, such derivatives can be prepared by simple quaternization of tertiary aminoalkyl ethers by reaction with methyl iodide. Sulfonium (107) and phosphonium (108) starch salts have also been prepared and investigated. Further work has explained the synthesis of diethylaminoethyl starch (109) as well as the production of cationic starches from the reaction of alkaline starch with... 

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