Cyclic sulfates of 1,2-diols

Dioxathiolane 2,2-dioxides (cyclic sulfates of 1,2-diols) show, similar to open-chain dialkyl sulfates, the typical IR absorption bands of the —S02— group in the ranges 1196-1221 and 1365-1401 cm-1 (60JCS201). l,2,3-Oxadithiolan-5-one 2-oxides are characterized by the S=0 band at 1170 cm-1 and the C=0 band at 1800 cm-1 (77MI43301). 

Nonaka and coworkers [177,178] found that a stereoselective one-electron reductive elimination reaction of cyclic sulfates of 1,2-diols proceeded to provide the tra/ .s -olefins and disulfate dianions of the parent diols. This reaction may be not only stereoselective but also stereospecific. An epoxide was also stereoselectively and regioselectively reduced to the monoalcohol [179,180]. 

Cyclic sulfates of 1,2-diols 2.14 are transformed into monoalcohols by NaCNBHj in refluxing THF at pH 4-5 followed by hydrolysis, or regioseiectively to p-hydroxyesters by NaBH4 in DMA when R = COO -Pr [GS3] (Figure 2.10). 

Difluoromethyl phenyl sulfone is lithiated by LiHMDS at -78°, and the lithio species attacks cyclic sulfates of 1,2-diols and 1,2-amino alcohols to afford a,a-difluoroalkyl sulfones. The benzenesulfonyl group can be reductively removed (Mg, HOAc, NaOAc) or eliminated to provide 1,1-difluoroalkenes with an allylic OH or NH2 group. 

Lloyd and Porter have conducted extensive mass spectroscopic studies of several cyclic sulfites and cyclic sulfates of 1,2-diols, 1,3-diols, and 1,4-diols. One important fragment of a cyclic sulfite of a 1,2-diol is extruded SO2 (77AJC569) (Scheme 2). 

Alkyl-substituted 1,3,2-dioxathiolane 2,2-dioxides can be prepared in a similar manner to the parent compound, ethylene sulfate (18) (66HC(2l-l)i) (cf. Scheme 10, Section 4.33.4.2.1). The method of choice is the permanganate oxidation of the corresponding cyclic sulfites (cf. Section 4.33.3.2.3) since the direct reaction of 1,2-diols with sulfuryl chloride often proceeds less smoothly than does the reaction with thionyl chloride. 4,5-Diaryl-l,3,2-dioxathiole 2,2-dioxides of type (186) are obtained by treatment of 9,10-... 

Dioxathiolane 2,2-dioxides (cyclic sulfate esters of 1,2-diols) are used in practice like sultones to introduce acid substituents into nitrogen heterocycles (48BSF1002), especially into cyanine dyes (58GEP1028718). Fluorinated derivatives are useful in the treatment of textiles such as cotton to impart wash and wear characteristics (62USP3055913). The conversion of cyclic sulfates into resinous film-forming polymers has been likewise patented (64USP3154526). 

Quinoline-containing 1,2,4-trioxolanes such as 107 have been patented as anti-malarial agents <05FRP2862304>. Further results on the reactivity of the novel 13,2-dioxathiolane-2-thione containing the cyclic thionosulfite function have appeared <05HCA1451> and a convenient method for direct conversion of 1,2-diols into cyclic sulfates using sulfuryl chloride has been described <05TA3908>. 

We have already seen how cyclic sulfates such as 123 can be converted into amino alcohols that might have been made by amino hydroxylation. The conversion of 1,2-diols, made by the AD reaction, into epoxides has been very widely used. A combination of acetyl bromide and an orthoester gives a bromo-acetate via an oxonium ion 182. The ion is formed with retention, bromide opens it with inversion at the benzylic centre, and epoxidation in base inverts it again. The net result is retention.39... 

The name cyclic sulfate originates from the sulfate ester of alcohols. Because in the present case the diol forms a part of the cyclic system, it is known as a cyclic sulfate. To avoid ambiguities, a systematic lUPAC nomenclature is required. Thus, the cyclic sulfite esters of 1,2-diols are named 1,3,2-dioxathiolane 2-oxides (1), and the corresponding cyclic sul-... 

To gain an insight into the likely hydrolytic behavior of sulfated simple sugars and polysaccharides, Brimacombe, Foster, Hancock, Overend, and Stacey carried out a rigorous set of experiments with the cyclic sulfates of cyclohexane cis-and trims-1,2-diol as model compounds. The results were interpreted on the reasonable assumption that, in all cases, the cyclic sulfates initially afford a diol monosulfate. Examples of both S-0 and C-0 bond cleavage were encountered. A qualitative reaction mechanism was proposed for use as a working hypothesis for the hydrolysis of sugar sulfates. 

Treatment of diethyl malonate and related compounds with 1,2-dihaloethane in the presence of base constitutes a classical method of cyclopropane synthesis296"300. The reaction can be conveniently carried out under PTC conditions. An improved method utilizing solid-liquid phase transfer catalysis has been reported298. The reaction of dimethyl or diethyl malonate with 1,2-dibromoalkanes except for 1,2-dibromethane tends to give only low yields of 2-alkylcyclopropane-l, 1-dicarboxylic esters. By the use of di-tm-butyl malonate, their preparations in satisfactory yields are realized (equation 134)297. The 2-alkylcyclopropane derivatives are also obtained from the reaction of dimethyl malonate and cyclic sulfates derived from alkane-1,2-diols (equation 135)301. Asymmetric synthesis... 

The most widely used method for the preparation of 1,3,2-dioxathiolane. Y-oxides (cyclic sulfites) 65 bearing C-linked substituents is the reaction of the corresponding 1,2-diols with thionyl chloride in presence of pyridine or Et3N (Scheme 18). More reactive 1,3,2-dioxathiolane. Y,.Y-dioxidcs (cyclic sulfates) 66 are usually obtained by oxidation of sulfites 65 with sodium periodate, which is mediated by mthenium tetroxide generated in situ from a catalytic amount of ruthenium trichloride. Numerous derivatives 65 and 66 were obtained via this approach and its modifications for further transformations, mostly as the synthetic equivalents of epoxides <1997AHC89, 2000T7051> (see also Sections 6.05.5 and 6.05.6, and Tables 1-7). 

Most compounds of this type are cyclic sulfite and sulfate esters of aromatic 1,2-diols as well as anhydrides of aromatic 1,2-disulfonic acids. The simplest representatives with unsubstituted benzene rings are 1,3,2-benzodioxathiole 2-oxide (48) (catechol sulfite), the corresponding 2,2-dioxide (156) (catechol sulfate) and 2,1,3-benzoxadithiole 1,1,3,3-tetroxide (158) (1,2-benzenedisulfonic anhydride). Compound (48) was synthesized by refluxing catechol with thionyl chloride in the presence of pyridine. In a similar fashion, from 2-mercaptophenol 1,2,3-benzoxadithiole 2-oxide was prepared (81AG603). The dioxide (156) was obtained in two steps by reaction of catechol monosodium salt with sulfuryl chloride in benzene at 0-10 °C and subsequent reflux of the intermediate (155) in the presence of pyridine. 

Reaction of cyclic sulfates or thionocarbonates, derived from 1,2-diols, with telluride results in stereospecific alkene formation <1995TL7209>. This is illustrated by the conversion of the cyclic sulfate OTitra-l,2-diphenyl-l,2-ethanediol 49 into fif-stilbene exclusively by Te, as shown in Equation (13). Treatment of the cyclic sulfate of 47-1,2-diphenyl-1,2-ethanediol with Te produces /ra r-stilbene exclusively. These results are accounted for by intermolecular Te Sn2 displacement followed by intramolecular Sn2 displacement to form the corresponding tellurirane. The tellurirane then thermally loses tellurium stereoselectively forming alkene. Cyclic sulfates need not be used dimethanesulfonates or di-/i-toluenesulfonates prepared from 1,2-diols also, stereospecifically, provide alkenes via telluriranes <1993CC923, 1996SL655>. 

Cyclic sulfates of unactivated diols, such as 2,3-butanediol, are reduced in DMF/0.4 M Et4NC104 at a mercury electrode at potentials less negative than the background reduction 2-butene (cis-trcms, 5 95) was formed in moderate yields, = 1 minor amounts of several unidentified compounds were seen in GLC [75]. 

In other cases, it can be better to perform an AD reaction followed by nucleophilic substitution with a nitrogen nucleophile on the derived cyclic sulfate of the diol (cf. Section 3.2.6.1) [373, 374],... 

The cinchona alkaloids have opened up the field of asymmetric oxidations of alkenes without the need for a functional group within the substrate to form a complex with the metal. Current methodology is limited to osmium-based oxidations. The power of the asymmetric dihydroxylation reaction is exemplified by the thousands (literally) of examples for the use of this reaction to establish stereogenic centers in target molecule synthesis. The usefulness of the AD reaction is augmented by the bountiful chemistry of cyclic sulfates and sulfites derived from the resultant 1,2-diols. 

Sharpless and Kim reported a one-pot synthesis of cyclic sulfates 96 from 1,2-diols via catalytic oxidation with ruthenium chloride51. The cyclic sulfates 96 thus formed on treatment with nucleophiles give /2-sulfates 97, which in turn are hydrolyzed to the / -hydroxy compounds 98 (equation 54). Hence the cyclic sulfates 96 are synthetically equivalent to epoxides. The results of ring opening of cyclic sulfates 96 are shown in Table 4. When the reaction of 99 with malonate anion is carried out in DME, the /2-sulfate moiety serves as a leaving group to give cyclopropane 100 (equation 55)51. 

Cyclic sulfites. 1,2-Diols form cyclic sulfites very readily. Although there are few important synthetic uses for these compounds, their oxidation to cyclic sulfates provides excellent substrates for nucleophilic substitutions. Tetrahydrofuran ring closure in an intramolecular attack has enormous implication for the synthesis of a family of natural products, because proper design can precipitate a cascade process. 

A similar rearrangement attempted on a five-membered cyclic sulfite failed to yield either a four-membered sulfone or an elimination product. However, tetramethyl-l,3,2-dioxathiolane 2,2-dioxide furnished pinacolone in good yield when heated under aqueous acidic conditions (74JOC3415). In contrast, six-membered cyclic sulfates derived from a number of 1,3-diols underwent a smooth ring contraction reaction when treated with lithium powder and a catalytic amount of 4,4 -di-/ert-butylbiphenyl (DTBB, 5 mol%) in THF at 0°C followed by hydrolysis as shown in Scheme 24 (95T11445). 

---