Sulfite esters cyclic

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. 

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. 

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... 

Likewise, unprotected polyhydroxy compounds can be successfully fluorinated to give the products resulting from substitution of the hydroxy groups by fluorine, wn-o-lnositol reacts with sulfur tetrafluoride and anhydrous hydrogen fluoride at ambient temperature to give a moderate yield of the cyclic sulfite ester of tw/o. cfo-5,6-difluoro-7-oxabicyclo[2.2.1 heptane-e.w,e.vo-2,3-diol (6) and, alter hydrolysis, the free difluoro diol 7.61... 

Konovalova and Orekhov103 demonstrated that the primary hydroxyl group in platynecine is more reactive to acylation than the secondary. For example, use of more or less drastic conditions yields platynecine di- or mono-benzoate, respectively. Pyrrolizidine alcohols can be esterified with inorganic acids e.g., mild treatment of platynecine with thionyl chloride yields the cyclic sulfite ester hydrochloride79 (see Section III, A). 

Of related interest in this connexion is the discovery of Deni eUe43 that the cyclic sulfite ester of 2,3-butanodiol gives on heating 2,3-epoxybutane and sulfur dioxide, along frith other products (Eq. 316). 

The diols (97) from asymmetric dihydroxylation are easily converted to cyclic sulfite esters (98) and thence to cyclic sulfate esters (99). ° This two-step process, reaction of the diol (97) with thionyl chloride followed by ruthenium tetroxide catalyzed oxidation, can be done in one pot if desired and transforms the relatively unreactive diol into an epoxide mimic, i.e. the 1,2-cyclic sulfate (99), which is an excellent electrophile. A survey of reactions shows that cyclic sulfates can be opened by hydride, azide, fluoride, thiocyanide, carboxylate and nitrate ions. ° Benzylmagnesium chloride and the anion of dimethyl malonate can also be used to open the cyclic sulfates.Opening by a nucleophile leads to formation of an intermediate P-sulfate anion (100) which is easily hydrolyzed to a p-hydroxy compound (101). ° Conditions for catalytic acid hydrolysis have been developed that allow for selective removal of the sulfate ester in the presence of other acid sensitive groups such as acetals, ketals and silyl ethers. ... 

Of related interest in thi connexion is the discovery of I>eniv lle that the cyclic sulfite ester of 3,3-butanediol gives on heating 2,3> opoxybotane and sulfur dkneide, along with ctber products ( q. 31 ),... 

Chiral epoxides and vicinal diols (employed as their corresponding cyclic sulfate or sulfite esters as reactive intermediates) are extensively employed high-value intermediates in the synthesis of chiral compounds because of their ability to react with a broad variety of nucleophiles (Figs. 11.2-1 and 11.2-2). In recent years, extensive efforts have been devoted to the development of chemo-catalytic methods for their production19, 10]. Thus, the Sharpless methods allowing for the asymmetric epoxida-... 

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-... 

Similarly, cyclic sulfite and cyclic sulfate esters of the corresponding 1,2-diamines have been named 1,2,5-thiadiazole 1-oxide (5) and 1,2,5-thiadia-zole 1,1-dioxide (6). In this chapter, emphasis is placed on cyclic sulfites and cyclic sulfates however, the synthetic preparation and nucleophilic transformations of cyclic sulfamidites and cyclic sulfamidates are also compared. 

The - C NMR studies were conducted to determine the conformation of a cyclic sulfite and larger-ring cyclic sulfite esters (76CJC1428), since chemical shifts are highly sensitive to the stereochemistry of the S = 0 bond. - C NMR data for various substituted ethylene sulfites are presented in Table III. 

In the case of an ester cyclic sulfite, reaction was carried out at lower temperature (ca.-20°C) to furnish an azido alcohol. Higher reaction temperatures led to elimination, giving rise only to azido maleate (93JA10267). 

A few miscellaneous cyclic esters are known in this class. The cyclic sulfinic ester (402) (a sultine) is formed in 40% yield, but no proof has been offered that the compound is not a 16-membered dimer <76CJC3012>. The cyclic sulfites (403) and (404) are obtained, together with their 16-membered dimers, by the action of thionyl chloride on the appropriate glycol (80TL1039). 

Acidolysis of cyclic sulfites with sulfuric acid and ester interchange with dimethyl sulfate produce cyclic sulfates (104). 

This method is also used with alcohols of the structure Q(CH2)kOH (114). Halo alkyl chlorosulfates are likewise obtained from the reaction of halogenated alkanes with sulfur trioxide or from the chlorination of cyclic sulfites (115,116). Chlorosilanes form chlorosulfate esters when treated with sulfur trioxide or chlorosulfiiric acid (117). Another approach to halosulfates is based on the addition of chlorosulfuric or fluorosulfuric acid to alkenes in nonpolar solvents (118). 

There are many reagents that add two OH groups to a double bond.705 OsO470< and alkaline KMn04707 give syn addition, from the less-hindered side of the double bond. Osmium tetroxide adds rather slowly but almost quantitatively. The cyclic ester 69 is an intermediate and can be isolated,7(18 but is usually decomposed in solution, with sodium sulfite in ethanol... 

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