Sulfinates arylation

Scheme 1-121. Triaryl(trifluoromethyl)stilbenes (167) by sulfinate/aryl displacement.

Carbon-sulfur bonds can be formed by the reaction of elemental sulfur with a lithio derivative, as illustrated by the preparation of thiophene-2-thiol (201) (700S(50)104). If dialkyl or diaryl disulfides are used as reagents to introduce sulfur, then alkyl or aryl sulfides are formed sulfinic acids are available by reaction of lithium derivatives with sulfur dioxide. 

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. 

Benzopentathiepin rapidly reacts with sodium sulfinates RS02Na (R = alkyl or aryl) in ehloro-form/methanol at 20 °C to afford high yields of thiosulfonates RS02SNa.406... 

Aryl- and alkyl-magnesium halides were the first reagents used to form sulfoxides from sulfinate ester 19 and related (— )-menthyl arenesulfinates (equations 564,665,758 and 866). Whereas optically pure esters produced the homochiral sulfoxides shown in equations (5), (6) and (7), the ester shown in equation (8) was an oily mixture of four diastereomers which led to formation of a meso sulfoxide and a d, l pair enriched in one enantiomer. A homochiral sulfoxide was obtained by fractional crystallization. 

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 H and 13C CIDNP studies have shown that not only the sulfone 14, but also the sulfmic ester 15, is generated as cage products from the phenyl/p-toluenesulfonyl radical pair during the thermal decomposition of phenylazo aryl sulfone (13)54 (Scheme 2). The cross-termination of arenesulfonyl and triethylgermyl radicals was found to occur exclusively via the formation of germyl sulfinate, ArS(0)0GeEt333. 

Aryl sulfones have been prepared from sulfinic acid salts, aryl iodides and Cul. Unactivated thiocyanation has been accomplished with charcoal supported copper(I) thiocyanate." ... 

Reaction between aryl halides and sulfinate ions... 

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]. 

Sulfur dioxide (see above) as well as S02, SO , and SOj have been used as building blocks in three-component sulfone syntheses. It has long been known that aromatic sulfinic acids are easily available from diazonium salts and sulfur dioxide under copper catalysis . Mechanistically, aryl radicals as reactive intermediates add to sulfur dioxide generating arenesulfonyl radicals, which either take up an electron (or hydrogen) yielding a sulfinic acid or add to an olefinic double bond yielding final y -halogenated alkyl aryl sulfones (equation 78). 

In (62) a second molecule of thiolsulfinate performs the nucleophilic attack on the protonated thiolsulfinate. The key intermediates [16] and [17] are similar to the key intermediate [13] in the aryl thiolsulfinate disproportionation, and the chemistry suggested in (64)-(66) either has precedent in the behavior of [13] or in known reactions of sulfenic and sulfinic acids. 

Second, partial decomposition of an aryl thiolsulfinate specifically labeled (35S) at the sulfinyl sulfur indicates (a) some incorporation of label in ArSSAr, which would not be expected if (75) were the only path for formation of disulfide (b) a significantly unequal distribution of label beween the two sulfurs of ArS02SAr [in its simple form (76) predicts both sulfurs should be equally labeled] (c) some incorporation of label into the sulfenyl sulfur of the recovered unreacted thiolsulfinate. The specific reactions responsible for these variations of the 35S-distribution from the pattern predicted by (74)-(76) cannot be pinpointed with certainty, although Koch et al. (1970) considered that a homolytic decomposition (80) of sulfenyl sulfinate [20], competitive with its... 

In aqueous dioxan aryl sulfinyl sulfones undergo rapid (tin = 43 s for PhS(0)S02Ph at 21° in 60% dioxan) uncatalyzed hydrolysis to sulfinic acid (135). This spontaneous hydrolysis has a low activation energy ( a = 9.4 kcal mol-1 for Ar = /j tolyl), but a large negative entropy of activation (/IS4 =... 

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