Cyclic Sulfite

Cyclic Sulfites and Sulfates (epoxide equivalents) Syntfiesis 1992, 1035. 

Dicyano-l,2,3-trithiole 2-oxide (143) has been prepared from the silver salt of 2,3-dimercaptomaleonitrile (142) and thionyl chloride (66HC(2l-i)67). Similarly, the reaction of ethylene glycol (144) with thionyl chloride gave 1,3,2-dioxathiolane 2-oxide (145), the parent compound of saturated five-membered cyclic sulfites (see Chapter 4.33). 

Although carbanionic and enolate species are most often sulfinylated using sulfinate esters, particularly homochiral ester 19, other tricoordinate S(IV) compounds may be used in their place. Sulfinamides (66) and cyclic sulfite ester-amides (67) are two examples of such compounds. 

Although the Sharpless asymmetric epoxidation is an elegant method to introduce a specific defined chirality in epoxy alcohols and thus, in functionalized aziridines (see Sect. 2.1), it is restricted to the use of allylic alcohols as the starting materials. To overcome this limitation, cyclic sulfites and sulfates derived from enantiopure vfc-diols can be used as synthetic equivalents of epoxides (Scheme 5) [12,13]. 

C-chiral racemic y-hydroxy sulfides were also resolved using PEL under kinetic resolution conditions. The products were transformed into optically active 3-(alkanesulfonyloxy)thiolane salts (Scheme 1). Similarly, 1,2-cyclic sulfite glycerol derivatives cis and trans) were resolved into enantiomers via a Pseudomonas cepacia-catalysed acylation with vinyl butyrate. The E values depended on the solvent used and varied from 2 to 26. ... 

This reagent combination also converts carboxylic acids to acyl chlorides (see Section 3.4.1). The mechanistic basis for the special effectiveness of benzotriazole has not yet been determined, but it seems likely that nucleophilic catalysis is involved. Sulfinyl ester intermediates may be involved, because Z-2-butene-l,4-diol gives a cyclic sulfite ester with one equivalent of reagent but the dichloride with two equivalents. 

Cyclic sulfites and sulfates are obtainable by the following reactions [29H31]... 

The activation of an anomeric hydroxyl group from partially protected or unprotected monosaccharides can be achieved via 1,2-cyclic sulfite formation. A subsequent trans-ring opening with azide N3 affords one anomeric derivative exclusively 133... 

A review of cyclic sulfites and sulfates in organic synthesis includes many examples of 1,3,2-dioxathiolane 5-oxides and 5,5-dioxides <0OT7O51>. Reaction of cyclic sulfates such as... 

Scheme 4.34 Preparation of cyclic sulfites from glycols.

The 1,2-cyclic sulfites are readily obtained from anomeric mixtures of 1,2-diols by reaction with sulfinyl diimidazolide as mixtures of exo- and endo-isomers at sulfur (Scheme 4.34) [312-314],... 

The cyclic sulfites were first found to react with lithium phenoxides as nucleophiles in DMF in a one-pot procedure commencing from the unprotected diol [357]. Subsequent work opened up this class of donor to alcohol nucleophiles in conjunction with the use of a Lewis add, such as Yb(OTf)3 or Ho(OTf)3, to activate the donor in refluxing toluene (Scheme 4.57) [314,358,359]. The very high degree of P-selec-tivity observed in these reactions is consistent with an SN2-like displacement of the sulfite oxygen. 

Colonna, S., Gaggero, N., Carrea, G. and Pasta, P., Oxidation of organic cyclic sulfites to sulfates a new reaction catalyzed by cyclohexanone monooxygenase. Chem. Commun., 1998, 415. 

Cyclic sulfites (320) have been shown to react with sodium acetoacetate (321 ... 

Fig. 5 gives examples of many of the types of sulfur-containing pesticides which are currently in use or have been used. It is clear that the types of functionalities present, e.g. organophosphate derivatives, chlorocarbons, sulfanamides, dithiocarbamates, oxime derivatives, and cyclic sulfite esters are "unnatural" (or at least presently "unnatural") groupings... 

Related imino alditols such as azepanes or lactam derivatives have been obtained and have shown to be glycosidase inhibitors [96, 100]. Both d- and l-gulonolactone have been converted into polyhydroxylated 1,6-aldonolactams of type 79 in a sequence of straightforward functional transformations, including sulfinylation of the corresponding aldonolactone-derived acetonides 76 that gave 5,6-cyclic sulfites 77 (Scheme 23) [101]. The latter reacted with sodium azide... 

Oxidation of cyclic sulfites to sulfates was accomplished with RuClj/aq. Na(IO )/CH3CN-CCiyO°C and a large-scale oxidation of D-mannitol-l,2 5,6-diacetonide-2,3-cyclic sulfite to the sulfate described (Fig. 5.17) [437]. The system RuO /aq. Na(10 )/CHCl3 converted cyclic sulfite diesters to the sulfates (Fig. 5.18) [438]. Oxidations of thiophene and aUcyl- and aryl-substituted thiophenes by RuCyaq. Na(ClO) were compared with similar reactions effected by stoich. [MnOJ- [439]. 

RuCyaq. Na(lO )/CH3CN-CCiy0°C (D-mannitol-1,2 5,6-diacetonide-2,3-cyclic sulfite (6 g) to the sulfate) [116], and stoich. RuOyCCl (ca. 5 g methyl-p-tolyl, meth-ylbenzyl and triphenyl-methyl phenyl and diphenyl sulfides to the sulfones) [99,122],... 

The endiol-cyclic sulfite 19 obtained by oxidation of the dihydropyran 18 affords a trans-fused bipyran <99TL2235> and this system is also accessible from the sulfonyl-stabilised oxirane 20 (Scheme 6) <99TL8019>. 

No theoretical studies were reported in the previous volume <1996CHEC-11(7)89> for these 5-5 bicyclic systems. Since then a number of computational studies have been carried out. The structure and properties of cyclic sulfites 3a and 3b and thionosulfites 3c and 3d have been reported <2003HAC587, 2005HCA1451>. Density functional theoretical (DFT) calculations using the Becke s exchange with Lee, Yang, and Parr correlation functional (B3LYP/6-31G level) have shown that the cyclic sulfite 3b is more stable than its diastereomer 3a. 

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