Reductive aliphatic sulfones

In analogy to the reduction of aliphatic halogen compounds, the reduction of sulfonates can be used for the alkylation of phenylacetic acids 435) ... 

Simple aliphatic sulfones, RS02R are polarographically inactive both in pro tic and aprotic media methylene disulfones are, however, reducible in DMF at potentials close to the decomposition potential of the medium. S-Disulfones and benzyl sulfones are rather acidic and may function as proton donors during the reduction, and their anions are generally not reducible [150]. Alkyl aryl sulfones and diaryl sulfones are reducible under protic and aprotic conditions [151-154] during the reduction of long chain aryl alkyl sulfones the EGB may induce a 6-cleavage, and in some cases dimerized products are observed [155]. The electrochemistry of sulfones has been reviewed by Chambers [103] and Simonet [156]. 

Since reductive elimination of aliphatic sulfones had already been studied in the early 1940s [8-10], all the pieces of the Julia sequence were at hand within the scientific community and assembling them to generate a powerful alkenylation methodology was simultaneously achieved by two different research groups. In fact, Umani-Ronchi et al. [11] published what can objectively be considered as the first Julia olefination sequence some two months before Julia [12] (Scheme 3.4). 

Samarium(II) iodide smoothly reduces primary, secondaryand tertiary aliphatic as well as aromatic nitro compounds to hydroxylamines (equation 52). This reaction was found to be highly versatile although with limited scalability, since at least four equivalents of Sml2 are necessary. Most functional groups, except aldehydes and sulfones, are compatible with Sml2 reduction (equation 53). 

Other Applications. Hydioxykmine-O-sulfonic acid [295043-8] has many applications in the area of organic synthesis. The use of this material for organic transformations has heen thoroughly reviewed (125,126). The preparation of the acid involves the reaction of hydroxylamine [5470-11-1] with oleum in the presence of ammonium sulfate [7783-20-2] (127). The acid has found application in the preparation of hydrazines from amines, aliphatic amines from activated methylene compounds, aromatic amines from activated aromatic compounds, amides from esters, and oximes. It is also an important reagent in reductive deamination and specialty nitrile production. 

Aliphatic primary and secondary amines can be linked to insoluble supports as ben-zylamines by reductive alkylation with support-bound benzaldehydes or by N-alkyla-tion with support-bound benzyl halides or sulfonates (Figure 3.25 see also Section 10.1). Benzhydrylamines and tritylamines are usually prepared by N-alkylation with the corresponding halides. 

For PEMFCs, the solid electrolytes are polymer membranes polymers modified to include ions, usually sulfonic groups. One of the most widely used membranes today is the polymer Nafion , created by the DuPont company. These membranes have aliphatic perfluorinated backbones with ether-linked side chains ending in sulfonate cation exchange groups [6, 7], Nafion is a copolymer of tetrafluoroethylene and sulfonyl fluoride vinyl ether [8] and has a semi-crystalline structure [9], This structure (which resembles Teflon ) gives Nafion long-term stability in oxidative or reductive conditions. The sulfonic groups of the polymers facilitate the transport of protons. The polymers consist of hydrophilic and hydrophobic domains that allow the transport of protons from the anode to the cathode [10, 11],... 

The protein is completely hydrolyzed by acid (6 N HCl, 24 hours or longer at 110°C, under vacuum or inert gas) to its constituent amino acids and the resultant hydrolysate is evaporated to dryness. The amino acid composition is determined on protein hydrolysates obtained after 24,48, and 72 hours of acid treatment. The content of amino acids with bulky aliphatic side chains such as isoleucine, leucine, and valine, which undergo slow hydrolysis, is calculated from an extrapolation of the hydrolysate data to infinite time. The content of hydroxyl-containing amino acids, which are slowly destroyed during hydrolysis, is obtained by a corresponding extrapolation to zero time. Since cysteine, cystine, and methionine residues are somewhat unstable to hydrolysis, these residues are oxidized to cysteic acid and methionine sulfone, respectively, with performic acid before quantitative analysis. Cysteine, or half-cystine, is quantitated as a derivative such as carboxymethyl cysteine after reduction and alkylation, a necessary prerequisite to subsequent sequence analysis. Tryptophan... 

Aromatic nitro groups Aromatic rings N-oxides Alkyl hydrazines Alkyl aldehydes N-methyl derivatives Monoalkenes p-Haloethyl mustards N-Chloroamines Alkyl N-nitrosoamines Alkyl esters of either phosphoric or sulfonic adds Aromatic mono- and dialkylamino groups Aromatic azo groups (because of possible reduction to aromatic amines) Aromatic and aliphatic aziridinyl derivatives Aromatic and aliphatic substituted primary alkyl halides Aromatic amines (including their N-hydroxy derivatives and the derived esters Propriolactones and propriosultones Derivatives of urethane (carbamates) Aliphatic and aromatic epoxides... 

A sugar-based synthesis of the C29-C44 fragment of the spongipyran macro-lides has been reported. The iodide 81, derived from D-glucal (see Vol. 26, p. 127 and 150), was converted into the sulfone 82 as outlined in Scheme 17. This was then coupled via its anion to aldehyde 83, prepared from simple aliphatic precursors by asymmetric aldol condensations, followed by reductive desul-fonylation. The major product 84 had the indicated stereochemistry at C-38 and C-39 (macrolide numbering), and a minor product (4 1 ratio) was the epimer at C-38. The natural products have the configuration of this minor product, but the stereochemistry at C-38 of 84 could be inverted cleanly by an oxidation-reduction sequence. ... 

Both, aliphatic and aromatic disulfides such as diphenyl disulfide and di-M-butyldisulfide undergo rapid reduction to the thiol stage, each consuming 2 equiv of the hydride, 1 equiv for hydrogen evolution and 1 equiv for reduction. However, methylphenyl sulfide is inert toward Li 9-BBNH. Sulfoxides, sulfones, and sulfonic acids are inert to this reagent. 

In summary, the reactivity of various functional groups toward Li 9-BBNH is classified into four broad categories [18] (1) rapid- or fast-reduction aldehyde, ketone, ester, lactone, acylchloride, acid anhydride, epoxide, disulfide, -alkyli-odide, and tosylate (2) slow-reduction tertiary amide, alkylbromide, and aromatic nitrile (3) sluggish-reduction carboxylic acid, aliphatic nitrile, primary amide, nitro and azoxy compounds, and secondary alkylbromide and tosylate (4) inert olefin, oxime, alkylchloride, sulfoxide, azo-compound, sulfide, sulfone, and sulfonic acid. 

Optically active (3-hydroxy sulfides 48 and sulfones 50 are extremely useful chiral building blocks because the a-carbon atom can be further functionalized and the sulfinyl and sulfonyl groups can be cleaved easily without racemization of the chiral center. Recently, Cho and co-workers reported highly effective syntheses for these compounds with excellent enantioselectivities by the 2b-catalyzed borane reduction of (3-keto sulfides 47 and sulfones 49 using EIANB (9) as the borane reagent (Table 11.9). The reduction is very effective for both aromatic and hindered aliphatic analogues [74, 75]. 

Deamination of aliphatic amines. Benzenesulfonylbenzylamine from benzyl-amine dissolved in aq.-alc. NaOH, solid hydroxylamine-O-sulfonic acid added portion wise, and distilled during ca. 1 hr. toluene. Y >95% based on startg. m. consumed conversion 63%.—A direct method for effecting reductive deamination of aliphatic prim, amines has not been hitherto available. F. e. s. A. Nickon and A. Sinz, Am. Soc. 32, 753 (1960). 

Sulfur Chemistry - Two facile methods of the heretofore difficult sulfoxide to sulfide reduction have been accomplished with dilsobutyl aluminum hydride and dichloroborane in THF at 0 . With the latter reagent, ketones, esters, and amides remain unaffected. A review on sulfoximes and derivatives as synthetic reagents presents some new methods for the preparation of various oxiranes, aziridines, alcohols, cyclopropanes, and alkenesAllylic sulfoxide anions have proven useful for the synthesis of ally lie alcohols, including trisubstltuted olefinic allylic alcohols. Transesterification between a dialkylacylphosphonate and a sulfonic acid yields sulfonate esters. The oxidation of aliphatic mercaptans to sul-finio acids with the use of m-chloroperbenzoic acid is especially useful in that the excess perbenzolc acid is removed by precipitation at -80. ... 

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