Lithium sulfinate

Scheme 2.1.4.3 Pd-catalyzed kinetic resolution of cyclic allylic carbonates with lithium sulfinates.

Synthesis of a polymer-bound methyl sulfone (R H) (Scheme 70) [314] Polystyrene bearing lithium sulfinate (332) (3.51 g) was allowed to swell in THF... 

PS/DVBsulfonyl)-3-sulfolene (Scheme 72) A suspension of polymer bearing lithium sulfinate (332) (10 g, 8 mmol), trans-3,4-dibromosulfolane (llg, 40 mmol), and pyridine (3.2 mL, 40 mmol) was stirred at 80 °C for 48 h, after which time the reaction was cooled to r. t., quenched with water, and filtered. The resin was washed as follows ... 

PS-TsCl has also been used as a reagent for a-chlorination of ketones (eq 15). p-toluenesulfonyl chloride has been used for the same transformation however, the solid-supported toluene-sulfonyl chloride offers the advantage of rendering the lithium sulfinate by-product insoluble and thus easily removed from the reaction mixture. 

Fig. 22 Crosslinking of poly(ether sulfone)s by conversion of lithium sulfinate groups with diiodobutane...

Organolithiums readily combine with organic azides to form adducts 46 (Scheme 1-37). If the former azide substituent R was aliphatic or aromatic, hydrolysis gives rise to a mixture of two triazenes or, depending on the substituent pattern, even just one of them. If R is /j-toluenesulfonyl or another good nucleofuge, lithium salt elimination produces a new azide (Scheme 1-37). Exceptionally a lithium sulfonylimide rather than a lithium sulfinate may get eliminated and, thus, diazocyclopentadiene is set free (Scheme 1-37). ... 

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. 

The lithium enolate of ethyl V-methoxyacetimidate (55) was also successfully sulfmy-lated by treatment with sulfinate ester 19 (equation 19)87. Sulfoxide 56 was used in an asymmetric synthesis of some /1-hydroxy esters. 

Similarly, the reaction of the parent thiirane dioxide, the 2-chloro- and 2,3-cis-dimethylthiirane dioxides with either Grignard or alkyl lithium reagents, has been studied extensively. The fair-to-good yields of the sulfinates (62) obtained (48-82%), accompanied by ethylene (or the corresponding alkenes for substituted thiirane dioxide), have been interpreted in terms of initial nucleophilic attack of the base on the sulfur atom as depicted in equation 17116. 

The zinc chloride is acting here as a Lewis acid. Similarly, thiirane dioxides react with metal halides such as lithium and magnesium chlorides, bromides and iodides in ether or THF to give the halo-metal sulfinates (130) in fair yields . 

The polarimetric method, in combination with the results of chemical correlation, made it possible to determine the optical purity of a range of chiral sulftnates (105-107), thiosulfinates (35,105), and sulfinamides (83) with the sulfur atom as a sole center of chirality. These compounds were converted by means of Grignard or alkyl-lithium reagents into sulfoxides of known specific rotations. This approach to the determination of optical purity of chiral sulfinyl compounds has at least two limitations. The first is that it cannot be applied to sterically hindered compounds [e.g., t-butyl /-butanethio-sulfinate 72 does not react with Grignard reagents]. Second, this... 

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]. 

Chlorides of sulfonic acids can be reduced either partially to sulfinic acids, or completely to thiols. Both reductions are accomplished in high yields with lithium aluminum hydride. An inverse addition technique at a temperature of —20° is used for the preparation of sulfinic acids, while the preparation of thiols is carried out at the boiling point of ether [69S]. 

Chlorine, Antimony trichloride, Tetramethylsilane, 4047 Chlorine, 2-Chloroalkyl aryl sulfides, Lithium perchlorate, 4047 Sulfin tetrafiuoride, 2-(Hydroxymethyl)furan, Triethylamine, 4350 Titaniiun, Halogens, 4919... 

Table 2.7.4.5 Selectivity of the Pd(0)/BPA-catalyzed kinetic resolution of rac-laa with lithium t-butyl-sulfinate.

The proposed mechanism of this reaction is composed by an initial S v2-type nucleophilic substitution reaction of 113 with the nucleophilic a-sulfonyl lithium carbanion to give the alkylmagnesium species (114) having a sulfonyl group at the / -position. Then, a -elimination reaction of magnesium sulfinate from the intermediate (114) occurs... 

The sulfonic acids of these metallocenes can be converted to sulfonyl chlorides, sulfonamides, etc., by appropriate reagents. Reduction of ferrocene-sulfonyl chloride by lithium aluminum hydride produces the rapidly oxidized ferrocenethiol in quantitative yield (43). Both the sulfonic acid of cyclopentadienylmanganese tricarbonyl and the corresponding sulfinic acid (obtained by sodium sulfite reduction of the sulfonic acid) have been converted to sulfones (10). 

Lithiation of dibenzofuran with butyllithium and mercuration both occur at the 4-position. Thallation occurs at the 2-position, however (57IZV1391). The mercury and thallium derivatives serve as a source of the iodo compounds by reaction with iodine. Bromodibenzofurans undergo bromine/lithium exchange with butyllithium and the derived lithio compounds may be converted into phenols by reaction with molecular oxygen in the presence of a Grignard reagent, into amines by reaction with O-methylhydroxylamine, into sulfinic acids by reaction with sulfur dioxide, into carboxylic acids by reaction with carbon dioxide and into methyl derivatives by reaction with methyl sulfate (Scheme 100). This last reaction... 

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