Reaction with sulfinic acid salts

Monohalogenothiazoles, 567 nucleophilic substitution reactions, 322 with amines. 567 with ArSH, 567 with benzamide, 567 with OH", 567 with OR", 567 relative reactivities, 568 with SR", 567 with sulfinic acid salts, 567 with sulfonamide, 567 reactions, with alkyl halides, 574 with n-butyllithium, 573 with Gtignard reagents, 573 reeduction of, with nickel, 573 with zinc, 573... 

Aryl sulfones have been prepared from sulfinic acid salts, aryl iodides and Formation of thiocyanates from unactivated aryl halides has been accomplished with charcoal supported copper(l) thiocyanate. " The copper catalyzed reaction of Na02SMe and aryl iodides give the aryl methyl sulfone. " A similar synthesis of diaryl sulfones has been reported using a palladium catalyst. " ... 

An inverse addition of sulfinic acid to a thiocarbonyl group could have taken place with the reactive intermediate 8, which should arise from thiophosgene and methanesulfmic acid (sodium salt)106 (equation 28). The first step of this reaction represents an S-acylation... 

Alkyl halides or alkyl sulfates, treated with the salts of sulfinic acids, give sulfones. A palladium catalyzed reaction with a chiral complexing agent led to sulfones with modest asymmetric induction. Alkyl sulfinates (R SO—OR) may be side products. Sulfonic acids themselves can be used, if DBU (p. 1337) is... 

Cycloadditions to a cyano group are comparatively rare. The high-temperature reactions of 1,3-dienes, e.g. butadiene, isoprene and 2-chloro-l,3-butadiene, with dicyanogen, propionitrile or benzonitrile result in formation of pyridines (equation 80)70. Sulfonyl cyanides 147, obtained by the action of cyanogen chloride on sodium salts of sulfinic acids, add to dienes to give dihydropyridines 148, which are transformed into pyridines 149 by oxidation (equation 81)71. 

Sulfenyl cldorides, sulfinic acids and sulfinyl chlorides were reduced in good yields by lithium aluminum hydride to disulfides [680], The same products were obtained from sodium or lithium salts of sulfinic acids on treatment with sodium hypophosphite or ethyl hypophosphite [507]. Sulfoxy-sulfones are intermediates in the latter reaction [507]. 

There is always a considerable amount of inorganic mercury left in the filtrate, which gives very little more of the tolylmercuric chloride when treated with more of the sulfinate. This may be present largely in the form of the mercuric salt of />-toluenesulfonic acid produced by the oxidation of some of the sulfinic acid liberated in a side-reaction. 

Sulfur nucleophiles have not been widely used in ir-allylpalladium chemistry, principally due to their ability to interfere with the catalyst by coordination. This is a less serious concern for sulfinic acid and sulfinate salts than with sulfides, and as a result, several reports have appeared using RSO2H and RSO2-.211-219 Alkenes allylically functionalized with a leaving group, dienes214 and vinyl nitro con-pounds218 219 have all served as precursors for the required ir-allyl species in these reactions (equations 60 and 61). 

Single crystals of difluoromethane bis(sulfinic acid) anhydride 17 were isolated, after the cesium salt 119 was stored in the presence of traces of water vapor for several weeks <1998JFC(89)55>. Treatment of difluoromethane-l,l-bis(sulfonyl fluoride) 120 with liquid ammonia led to the formation of the cyclic ammonium imide 121 <1997ZNB359, 1997WO9731909>, while reaction of sulfamide 122 with trifluoroacetaldehyde O-ethyl hemiacetal afforded the cyclic aminal 60 (Scheme 41) < 1999S1731 >. 

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. ... 

Methylisothiourea is formally analogous to an amidine or guanidine (see also reactions of amidine sulfinic acids earlier in this chapter). It reacts readily with acylvinylphosphonium salts in much the same way as amidines to give 2-methylthio-4-imidazolylphosphonium salts, which can be converted into multifunctional imidazoles with recovery of triphenylphosphine [28]. 

The oxidation of thiols follows a completely different course as compared with the oxidation of alcohols, because the capacity of the sulfur atom to form hypervalent compounds allows it to become the site of oxidation. Thiols are readily oxidised to disulfides by mild oxidants such as atmospheric oxygen, halogens or iron(III) salts (Scheme 6). This type of reaction is unique to thiols and is not undergone by alcohols, it is a consequence of the lower bond strength of the S-H as compared with the O-H bond, so that thiols are oxidised at the weaker S-H bonds, whereas alcohols are preferentially oxidised at the weaker C-H bonds (Scheme 7). The mechanism of oxidation of thiols may be either radical or polar or both (Scheme 6). The polar mechanism probably involves transient sulfenic acid intermediates like (7) and (8). In contrast, thiols react with more powerful oxidants, like potassium permanganate, concentrated nitric acid or hydrogen peroxide, to yield the corresponding sulfonic acids (10). This oxidation probably proceeds via the relatively unstable sulfenic (7) and sulfinic acids (9), which are too susceptible to further oxidation to be isolated (Scheme 8). 

Attyl and propargyl group transfer. Sulfinic acids or their sodium salts assist Pd(0)-catalyzed deallylation by accepting the allyl group. In addition to allylic esters, allylic sulfoximines can also deliver the allyl group to nucleophiles such as amines. Acrolein acetals react with 1,3-dicarbonyl compounds but the regiochemistry is strongly dependent on reaction temperatures. ... 

Dutt-Wormall reaction. Preparation of dia-zoaminosulfinates by reaction of diazonium salts with aryl- or alkylsulfonamides followed by alkaline hydrolysis to the corresponding sulfinic acid of the sulfonamide and the azide. 

In a similar way, pyridine phosphonium salts and phosphonates can be prepared by reaction of trivalent phosphorus compounds with the more accessible iV-trifluoromethanesulfonyl-pyridinium salts, when tri-fluoromethanesulfone is the leaving group from nitrogen (as sulfinate anion) attack is normally at C-4, as illustrated below. The A -trifluoromethanesulfonyl-pyridinium salts also react with ketones or with electron-rich aromatic compounds to give 1,4-dihydropyridine adducts. Subsequent treatment with potassium t-butoxide brings about elimination of trifluoromethanesulfinic acid, and thus aromatisation. It is also possible to utilise phosphonates in reaction with aldehydes, leading finally to 4-substimted pyridines. ... 

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