5.5- Dioxides, cyclic

Higher reactivity of 1,3,2-dioxathiolane j/A-dioxides (cyclic sulfates) toward nucleophiles, and practically guaranteed Sn2 stereochemistry of G-O bond cleavage, make them extremely useful synthetic intermediates <1996CHEC-II(4)545, 1997AHC89, 2000T7051>. The starting cyclic sulfates and the products of their reactions with O-nucleophiles are summarized in Table E... 

Table 1 Reactions of 1,3,2-dioxathiolane S,S-dioxides (cyclic sulfates) with O-nucleophiles... 

Several recent publications describe cleavage of 1,3,2-dioxathiolane. S -dioxides (cyclic sulfates) by halide nucleophiles that furnish halohydrines, which can be used as synthetic intermediates, primarily for preparation of corresponding epoxides or for further reactions with nucleophiles (Table 6). Similar reactions with chloride have been studied for 1,3,2-dioxathiolane J-oxides (cyclic sulfites) <1996ACS832>. 

It has been shown that 4-decyl-l,3,2-dioxathiolane AA-dioxide unexpectedly reacts with BuLi to give dodecanal in 99% yield <1994JOC520>. A few other examples of this base-mediated rearrangement of 1,3,2-dioxathiolane S,S-dioxides (cyclic sulfates) to ketonic products have been described (Table 7). The reaction may start with... 

The first enzymatic resolution of 1,3,2-dioxathiolane A-dioxides (cyclic sulfites) was achieved via lipase-catalyzed acylation with vinyl butyrate (Equation 17) <1999TA4755>. For the air-alcohol, 91% ee has been observed after 21% conversion for the ester. However, the enantioselectivity is too low for the resolution of the trans-alcohol <1999TA4755>. 

Dioxathiolane. Y-oxidcs (cyclic sulfites) and 1,3,2-dioxathiolane. Y,.Y-dioxides (cyclic sulfates) have been widely used in organic chemistry, mostly as the synthetic equivalents of epoxides (Sections 6.05.5 and 6.05.6 Tables 1-7). 

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). 

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). 

Heterocycles of this type occur widely. The benzo[l,3]dioxole ring system is often found in natural products and their degradation products, e.g., sesamol 38 lipoic acid 39 is a naturally occurring 1,2-dithiolane derivative. The 1,3-dithiolanes 40 are commonly known as 1,3-dithioacetals and have been extensively used in carbonyl group chemistry. In the absence of cyclic conjugation, ring sulfur atoms can readily exist in higher oxidation states as, for example, in the oxathiole S, -dioxide 41. 1,3,2-Dioxathiolane A-oxides 42 (cyclic sulfites) and 1,3,2-dioxathiolane A,A-dioxides (cyclic sulfates) are useful as synthetic equivalents of epoxides. 

Trithioles and 1,3,2-dioxathiolanes. 1,2,3-Trithiolanes are prepared by reaction of alkenes with elemental sulfur . The synthesis of 1,3,2-dioxathiolane -oxides (cyclic sulfites) and 1,3,2-dioxathiolane S, -dioxides (cyclic sulfates) is discussed in comprehensive reviews <1997AHC(68)89, 2000T7051>. The most widely used method for the preparation of 1,3,2-dioxathiolane A-oxides 557 is the reaction of the corresponding 1,2-diols 556 with thionyl chloride in the presence of pyridine or triethylamine (Scheme 251). More reactive 1,3,2-dioxathiolane S,A-dioxides 558 are usually obtained by oxidation of sulfites 557 with sodium periodate, which is mediated by ruthenium tetroxide generated in situ from a catalytic amount of ruthenium trichloride <1997AHC89, 2000T7051, CHEC-III(6.05.10.3)183>. 

The transamination of l,3-dihyro-2,l,3-benzothiadiazole-2,2-dioxides (cyclic sulphamides) (346) has successfully led to the formation of sulphamides353. Thus when cyclohexylamine, benzylamine and n-butylamine are used in a 1 1 ratio with 346, the fully exchanged iV,iV -dialkylsulphamides were obtained in 60 to 80% yield (equation 107). 

Hydrogen peroxide or peroxy acids oxidize thietanes to 1,1-dioxides (cyclic sulfones) via 1-oxides ... 

Z)-siloxy-2-ethylenes 43,813 thioethers 44,993 Sulfones, cyclic s.a. S,S-Dioxides, cyclic... 

Behr A, Thelen G (1984) Carbon-carbon coupling of carbon dioxide, cyclic hydrocarbon and nickel(0). Cj Mol Chem 1 137-153... 

Olefins may be converted in high yield to a-ahtoroketones by treatment with chromyl chloride in acetone. a-Carboxyketones, generally relatively inaccessible, can be prepared by treatment of ketones with lithium 4-methyl-2,6-di-tert-butylphenoxide and carbon dioxide. Cyclic ketones result from ring expansion of methylene cycloalkanes with cyanogen azide followed by hydrolysis, a procedure which complements the standard diazo-methane-ketone approach. Functionalized cis-bicyclic ketones can be synthesized by haloketal cyclizatlon followed by hydrolysis. ... 

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