Arylsulfinate

Arylalkylsulfones ate important intermediates obtained by alkylation of arylsulfinic acids. The latter ate obtained by reduction of the corresponding sulfonyl chloride. This reduction process is simple and of general appHcation involving the addition of the isolated sulfonyl chloride paste to excess aqueous sodium sulfite followed by salting-out the product and isolation. With mote rigorous reduction conditions, such as zinc/acid, sulfonyl chlorides ate reduced through to aryknercaptans, eg, 2-mercaptonaphthalene is manufactured from naphthalene-2-sulfonyl chloride. 

The cleavage of alkyl aryl sulfones by sodium amalgam and alcohols65 probably proceeds also through the intermediacy of a radical anion, followed by splitting to the arylsulfinate anion and an alkyl radical. Both the sulfinate anion and the disproportionation products of the radical have been observed. 

The thiazine dyes used in the preparation of this type of leuco are obtained through oxidative coupling of phenothiazine with an active methylene compound or an aniline. The reduction of the dye 23 with zinc powder in acetic acid is straightforward.9 Treatment of the leuco 24 with acetic anhydride at 40°C yields a more air stable leuco 25.9 Addition of arylsulfinic acid to thiazine dyes such as 26 produces directly leuco dyes such as 27.Sb... 

The homocoupling of aryl halide to diaryl compounds, known as Ull-mann coupling, is a synthetically useful reaction and has wide applications in material research. Such couplings have been studied in aqueous conditions. In 1970, arylsulfinic acids were coupled with Pd(II) in aqueous solvents to biaryls (Eq. 6.25).53 However, the reaction required the use of a stoichiometric amount of palladium. In the presence of hydrogen gas, aryl halides homocoupled to give biaryl compounds in moderate yields (30-50%) in an aqueous/organic microemulsion (Eq. 6.26).54... 

In the fourth and final step, the intermediate 2-(2,-hydroxyphenyl)ethen-l-sulfmate (HPESi ) is desulfinated to 2-(2 -hydroxyphenyl)ethan 1-al (HPEal). As seen from Fig. 4, this step cannot be catalyzed by the arylsulfinate desulfinase like DszB. Instead, the enzyme has to be an alkenylsulfmate desulfinase. The alkenyl C-S bond as present in the intermediate, can only be desulfurized by hydroxylase-type enzyme, giving an enol, which can then tautomerize to HPEal and sulfite. However, the identity of the sulfur-containing product has not been confirmed [34],... 

Azidation.1 Arylsulfonyl azides generally react with enolates to effect net diazo transfer, but this hindered and electron-rich azide can effect azide transfer at the expense of diazo transfer. The nature of the enolate counterion also plays a role, with K being more effective than Na. In addition, acetic acid (or KOAc) is required as the quench for decomposition of the triazine intermediate to the azide with elimination of the arylsulfinic acid, ArS(0)0H. By use of these conditions, chiral N-acyloxazolidones such as 2 undergo diastereoselective azidation to give the azides 3 in 75-90% yield and in high optical purity (>91 9). These... 

Aryloxytitanium halides, 25 83 2-Arylpyridines, 27 111 Aryl phosphate esters, 79 51 Aryl phosphates, 7 7 493 Aryl phosphonates, 79 37 Arylphosphorus compounds, 79 28 Aryls, palladium, 79 652 Aryl-silicon compounds, 22 553, 554 Arylsulfinic acids, 27 248-249 Arylsulfonylated gelatin, 72 444 Aryltin trihalides, 24 810-811 Arylyl amines, 70 396-399 Asahi Chemical Industries EHD processes, 9 676-677 sebacic acid production, 9 679-680 ASAM (alkaline-sulfite-AQ-methanol) process, 27 30... 

Cyanothioformamides NC-CS-NR1 -COR2 (R1 = Ph or 4-02NC6H4 R2 = CF3 or Ph) comprise another class of reactive dienophiles (e.g. equation 40)36. The trithiocarbon-ate 61 adds to cyclopentadiene to yield 62 (equation 41 )37. Trithiocarbonate. SVS-dioxidcs 63 (Ar1 = d-MeCgHa or 4-CIC6H4 Ar2 = Ph or 4-CIC6H4) react instantly with cyclopentadiene to afford mixtures of endo- and exo-cycloadducts 64 and 65, respectively, in which the former predominate (equation 42)38. The adducts produced from acyclic dienes are unstable they readily eliminate arylsulfinic acids to yield thiopyrans (equation 43)38. 

Treatment of alkyl nitrites with arylsulfinic acids 194 generates the unstable nitroso compounds 195, which, in the presence of dienes, are trapped as cycloadducts 196 (equation 109)102. 

Scheme 13 Reaction of ( )-alkenylbismuthonium salts with sodium arylsulfinates [37]...

More structurally complex epoxides can be ring-opened intramolecularly in a synthetically useful fashion. Thus, in their approach to methyl-substituted trmis-fused tetrahydropyran subunits found in marine natural products, Mori and co-workers <99TL8019> treated the polyfunctional arylsulfonyl epoxide 67 with Lewis acid to induce a (s-endo cyclization onto the epoxide moiety, with concomitant ejection of arylsulfinate, to provide the bicyclic ether 68. This system was found to be highly sensitive to the nature of the Lewis acid catalyst used. 

Table 2.1.4.2 Pd(0)/BPA-catalyzed kinetic resolution of the cyclic carbonate rac-laa with arylsulfinates.

Arylsulfinyl chlorides have been prepared by treating the corresponding arylsulfinic acids with an excess of thionyl chloride in thfe... 

Trisubstituted 2//-thiopyrans 299 add to arylsulfinic acids XC6H4S02H to afford sulfones 591. The addition was catalyzed with protons, and the detailed mechanism was discussed in reference 304. 

The 50 mol % excess of p-toluenesulfinic acid is required to obtain the best results. Using only 10-20 mole % excess of the sulfinic acid typically lowers the yield by 20-30%. This has been attributed to the known propensity of arylsulfinic acids to disproportionate.3 The checkers noted the presence of insoluble material after the addition of p-toluenesulfinic acid. This did not effect the yield. 

Arylsulfinic acids are perfluoroalkylated under the SRN1 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 O-alkylation reaction, has not been discussed. 

Sulfinates. Arylsulfinate anions were shown to be effective activators for photoreducible dye polymerization systems by Hiller, Margerum, and Rust (41). The work is described with applications in a number of patent publications (20,41a,42). These workers also studied the mechanism of the photoinitiation process (43). 

For a variety of arylsulfinate salts containing para-substituents of varying electron demand, it was shown under controlled polymerization conditions (1 M acrylamide monomer, pH 7, 4 x 10 3 M activator for methylene blue sensitization) (43b) that dye bleaching occurred with a quantum yield of 0.10-0.17 and that quantum yields for monomer loss were 1200-1700. The efficiency of the dye bleaching and the polymerization reaction increased as the electron donor ability of the sulfinate increased. ... 

Aryldiazosulfones of general structure Ar-N=N-S02Ar were shown to interact with excited dyes to yield aryldlazonium ions and arylsulfinate ions via a sensitized dissociation (9b) as shown in eq. 31. The sulfinate product can interact with another dye excited state to produce a sulfinyl radical capable of initiation in the conventional way (43.44). 

Sodium arylsulfinates and palladium salts react to form arylpaUadium salts and sulfur dioxide. When carried out in the presence of some dienes, stable organopalladium complexes have been obtained. For example, 1,5-cyclooctadiene and sodium p-toluenesulfinate with palladium chloride yields the a,it-complex shown in equation (48).109... 

Study of reactions in different solvents often provides crucial mechanistic evidence. This is the case in the reaction between thiolates and a -substituted nitroalkanes when changing from dipolar aprotic solvents to protic solvents. In contrast to the above reactions in dipolar aprotic solvents, where a mixture of disulfides and SRN1 products is obtained, disulfides are exclusively formed in methanol with no SRN1 products. Early studies had shown that SrnI substitution between a-substituted nitroalkanes and anions such as nitronates and arylsulfinates takes place at a slower rate in methanol. 

The apparent SN reactions of chlorosulfines with sodium arylsulfinates to give sul-fonylsulfines with inversion of configuration in high yield was suggested to proceed via an addition-elimination mechanism rather than an SN2 mechanism.58... 

Displacement of a nitro group has also been observed. 4,7-Bis(arylsulfonyl)benzofuroxans are formed from (56 n = 1) and arylsulfinates furthermore, the arylsulfonyl groups in the product may themselves be displaced by other nucleophiles. 

Oxoalkyl- and 3-oxoalkyl-triphenylbismuthonium salts transfer the alkyl groups to various hetero nucleophiles such as piperidine, triphenylphosphane, arylsulfinates, alcohols, arylthiolates, dimethyl sulfide, and metal halides under mild conditions (Equation (132)).214 215 Methyl- and allyl-triphenylbismuthonium salts also alkylate some heteronucleophiles.216 The leaving ability of the triphenylbismuthonio group has been found to be higher than that of the triflate anion. 

The mechanism involves deprotonation with a very strong base, usually butyliithium or LDA. to form the hydrazone aza-enolate, which then eliminates arylsulfinate to give an unstable anion. Loss of nitrogen, which is extremely favourable, leads to the vinyl lithium. 

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