Aryl sulfinates

Arylsulfmic acids are perfluoroalkylated under the conditions, but the yield IS low [77 (equation 70) The isolated product is an aryl perfluoroalkyl sulfone. The possible formation of a perfluoroalkyl aryl sulfinate intermediate, arising from an 0-alkylation reachon, has not been discussed. 

Recently, the scope of the allylic substitution has been extended to sulfinate salts 84 to obtain allylic sulfones 85. Due to solubility problems of both nucleophile 84 and carbonate leaving group, a polar solvent mixture of DMF and 2-methoxyethanol had to be employed, which limits the reaction to the use of a phosphine ligand. Thus, various aryl sulfinates 84 and functionalized carbonates 81 could be converted to the corresponding allylic sulfones 85 with good to excellent yields and regioselectivites and complete retention of stereochemistry (eq. 2 in Scheme 20) [65]. 

Sulfenyl chlorides react with zincalkyl (or -aryl) sulfinates and also with sodium benzene sulfinate to yield the corresponding esters of thiosulfonic acid 13, 111, 161) ... 

Heterolytic scission of the -S-S- bond in which only electrophilic assistance is involved is the exception rather than the rule in reactions involving bond fission of this type. Kice et a/.165,166 have demonstrated that a variety of S-S bond cleavages involve concomitant electrophilic and nucleophilic catalysis including (a) the formation of aryl thiolsulfones from aryl thiolsulfinates and aryl sulfinic acids and (b) the hydrolysis (acetic acid—1% water and 60%... 

J Vinyl Substitutions with Carboxylic Acid Halides, Aryl Sulfinates and Arylsulfonyl Chlorides... 

The key step is the elimination of the aryl sulfinate and this has been improved by using aryl hydrazones with bulky isopropyl groups on the 2-. 4-, and 6-positions ofthe aromatic ring to accelerate the elimination. The weakness of this approach to vinyl silanes is that the position ofthe... 

Aryl sulfinic acids behave similarly to thiols toward urrsaturated kctoba,scs. The addition to double bond is preferred, particularly under acidic conditions, to amino group replacement. ... 

Salts of sulfinic acids ace converted to sulfones by the action of pri-lary/ secondary, and benzyl halides, alkyl sulfates, and aryl halides in which the halogen atoms are activated by nitro groups in the ortbo or para positions. The reaction fails with t-amyl halide. The yields vary widely, depending upon the nature of the reactants. From salts of benzenesulfinic acid and simple alkylating agents, sulfones are produced in 50-90% yields. Satisfactory results have been obtained when the aryl sulfinic acid contains nitro, cyano, and acetamido groups. Keto sulfones are made in 48-62% yields by alkylation with a-halo ketones. ... 

The sodium salts of aryl sulfinic acids react rapidly with DECP in refluxing THF to give aryl thiocyanates in good yields, and even hindered substrates give the corresponding thiocyanates. ... 

Carbanions derived from a-sulfonyl ethers 5 undergo [2.3] sigmatropic rearrangement the resulting a-hydroxy sulfoties are subject to a further fragmentation, yielding an aryl sulfinic acid and an aldehyde which reacts further with excess alkyllithium Lo afford a secondary homoallylic alcohol61 66. 

Compounds with activated halogen atoms, e.g., 7-chloro-4-nitrobenzo-furoxan (234), undergo displacement reactions with a variety of nucleophiles, including sulfides,300 443,444 amines,300,443,491 phenoxides,300 and others mentioned earlier.6 Sometimes rearrangements of the type discussed in Section V,C,4 occur, leading to products other than those of simple displacement.300,443 When 7-chloro-4-nitrobenzofuroxan is treated with an aryl-sulfinate, both substituents are replaced, and the 4,7-bisarylsulfonyl compound is formed. One of the arylsulfonyl groups is, in its turn, susceptible to replacement by other nucleophiles.444... 

The desulfitative Heck-type reaction of aryl sulfinic acids ArSOjH with terminal alkenes RCH=CH2, catalysed by (AcO)2Pd in the presence of (AcO)2Cu as oxidant, has been reported to produce the corresponding rra 5-alkenes RCH=CHAr no ligand or base is required. ... 

The last class of nucleophiles used to scavenge the n-allylpalladium intermediate is that of sulfur nucleophiles. 2-Thiobenzoic acid has been used as a water-soluble scavenger of 7r-allylpalladium complexes in allyl carbamate deprotections. More recently, aryl sulfinic acids have been demonstrated to very effectively serve as nucleophiles in the Pd-mediated deprotection of allyl esters, carbamates, amines, and ethers. This reagent appears to afford substantially bettCT reactivity than most other classes of nucleophiles. 

To a stirred solution of alkene (1 1 mmol) and sodium aryl sulfinate (2 2 mmol) in acetonitrile (10 mL) was added with Kl (10 mol%), Nal04 (10 mol%) and catalytic amount of acetic acid. The resulting reaction mixture was stirred at room temperature for the appropriate time (2.5-7 h as monitored by TLC). After completion of the reaction, the mixture was quenched by the addition of a saturated aqueous solution of sodium thiosulfate (5 mL) and extracted with ethyl acetate (2 X 10 mL). The organic layer was separated and concentrated, and the residue was subjected to column chromatography (silica gel hexane-EtOAc) to obtain the pure product of vinyl sulfone 3. All compounds were characterized based on detailed spectral studies and elemental analyses. 

In addition, other electrophiles, such as arylsulfonyl hydrazides, aryl sulfamates, aryl sulfinates, or alkenyl phosphates, have been reported to arylate heterocycles, such as benzoxazoles or xanthines. 

The palladium-catalyzed coupling of aryl halides with a sodium aryl sulfinate afforded symmetrical and unsymmetrical diaryl sulfones in good to excellent yield (Scheme 5.47) [69]. A common palladium(O) compound was used as the metal source, and XantPhos served as the supporting/stabilizing ligand. A base was also needed for this chemistry, and... 

The palladium-catalyzed coupling of sodium aryl sulfinates with aryl halides would be a reasonable approach [69]... 

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