Sulfoxides with sodium periodate

Next, the protecting group was removed with acid, and the sulfide was oxidized to the sulfoxide with sodium periodate (NaI04) ready for elimination. Heating to 110°C then gave the Queen Bee Substance in 86% yield. 

Only sulfoxidation, and no elimination, occurs when the hydrochloride of 2 (R = Me) is treated with sodium periodate at room temperature.3 Ketone 4, which represents the tautomeric form of dibenzo[6,/]thiepin-10-ol, can be sulfoxidized with hydrogen peroxide at room temperature to provide sulfoxide 5 in 56% yield however, at reflux temperature oxidation occurs additionally at the carbon atom next to the oxo group and sulfone 6 is isolated in 79% yield.3... 

Dihydro-l-benzothiepin 1-oxide (21) is obtained in 77% yield when 19 is treated with sodium periodate in glacial acetic acid at 0 °C, while a second method ultilizing sulfuryl chloride at — 70°C gives the dichlorosulfurane intermediate 20 and ultimately the sulfoxide 21 in 79% yield.86... 

Quench the reaction by immediate gel filtration on a desalting column. If a dextran-based resin is used for the chromatography, the support itself will react with sodium periodate to quench excess reagent. Alternatively, N-acetylmethionine may be added to quench the reaction, because the thioether of the methionine side chain will react with periodate to form sulfoxide or sulfone products (Geoghegan and Stroh, 1992). In addition, sodium... 

The next step was to introduce the alkyl chain—this was best done by first oxidizing the sulfide to a sulfoxide, using sodium periodate. The sulfoxide was then deprotonated with -BuLi and alkylated with an alkyl iodide containing a carboxylic acid protected as its r-butyl ester. Reduction of the sulfoxide and hydrolysis back to the free acid gave biotin. 

It has been shown66 that, whereas oxidation of 104 with sodium periodate affords a mixture of the axial and equatorial sulfoxides, 102 and 103, in which the equatorial sulfoxide preponderates (the ratio of 102 103 is 10 1), similar oxidation of 105 affords a mixture of 106 and 107 in which the axial isomer preponderates (ratio of 106 107,... 

Reduction of 91, respectively 92, with zinc borohydride, separation of the C, 5-isomers, followed by hydrolysis gave (d/)-9-deoxy-9-thiaprostanoid 93 and diy 1 l,15-epi-9-deoxy-9-thia-prostanoid 94. Oxidation of 93 with sodium periodate produced a mixture of two epimeric sulfoxides 95, which were partially separated by preparative thin layer chromatography. 

The pentaacetate 232 is readily oxidized with sodium periodate to a crystalline sulfoxide (234). It could not be decided whether this substance contains only one of the two isomers possible. The sulfoxide 234 is a sugar in which all of the atoms in the ring are asymmetric. Further oxidation of 234, or direct oxidation of the pentaacetate 232, with hydrogen peroxide in acetic acid gives the sulfone 235. 

Sulfides containing sulfur in the ring are oxidized to cyclic sulfoxides. Ethylene sulfide, upon treatment with sodium periodate in aqueous methanol at 20-25 °C, is converted into ethylene sulfoxide in 65% yield [768]. With peroxybenzoic addin dichloromethane, a 77% yield is obtained [309] (equation 558). 

Sulfenylation of lithium enolates with PhS-SPh or of silyl enol ethers with PhS-Cl allows any a-PhS carbonyl compound to be made regioselectively, e.g. 149 and 152 from 147 (see chapter 5). Oxidation with sodium periodate gives the sulfoxide without over-oxidation to the sulfone, but elimination requires reasonably high temperatures (about 120 °C for MeSO but only about 50 °C for PhSO). Together with the unpleasant by-products, the results of disproportionation of unstable PhSOH, this has led to a preference for the selenium version of the reaction, though we must admit that the by-products are even more offensive.22... 

The most widely used method for the preparation of dihydrothiazine oxides involves the oxidation of the parent dihydrothiazines with sodium periodate or w-chloroperbenzoic acid.79,95,98,100-102,113.114 jn certajn jn stances, oxygen will act as the oxidant for example, the sulfoxide 187 was formed when a cyclohexane solution of the compound 117 was exposed to the air.44,46,86 The mechanism of this reaction, in which the thiazolidine 186 was a co-product, has already been discussed (Section V,C,2,b). 

Perhydropyrrolo[2,l-6]thiazol-3-one (278) can be oxidized to the sulfoxide (279) with sodium periodate or to the sulfone (280) with H2O2. By reaction with n-butyllithium an enolate has been obtained. By reaction of this enolate with some electrophiles, such as esters or ketones, the corresponding 2-substituted perhydropyrrolo[2,l-i]thiazolones (281) or (282) have been obtained. These reactions are shown in Scheme 50. 

Oxidative Cleavage Reactions. Among the numerous methods for 1,2-diol cleavage there exist only a few that involve catalytic ruthenium reagents, for example Ruthenium(III) Chloride with Sodium Periodate Attempted selective monooxidation of a 1,2-diol to the hydroxy aldehyde with catalytic TPAP and NMO resulted in carbon-carbon bond cleavage to provide the aldehyde (eq 11). Furthermore, attempted oxidation of an anomeric a-hydroxy ester failed instead, in this case decarboxy-lation/decarbonylation and formation of the lactone was observed (eq 12). However, Dimethyl Sulfoxide-Acetic Anhydride provided the required a-dicarbonyl unit. Retro-aldol fragmentations can also be a problem. ... 

In another system [118], a prochiral sulfide is chemically converted into an optically active sulfoxide with appreciable enantioselectivity (ee 80%) upon reaction on the surface of a clay-ehelate adduct, A-tris-(l,10-Phenanthroline) nickel(II)-montmorillonite. The sulfide is added to a mixture of methanol/water (3 2) and is absorbed by the adduct. Under these conditions, the oxidation is effective with sodium periodate at room temperature in excellent yield (range of 80-90%) (Table 1.6). 

Recendy, we described a useful sequence where Michael-acceptor sulfoxides 30 were obtained in two steps from homopropargylic alcohols 29 by radical addition of thiophenol and oxidation with sodium periodate. The unsaturated sulfoxides were used in a highly stereoselective intramolecular oxa-Michael reaction. The sequence provided stereoselective functionalization of the sulfoxide moiety, and the products 31 proved to be useful in the synthesis of modified furanosides 32. This represents a good exanple where sugars are prepared from acyclic precursors. The Michael addition was followed by a hydrolytic Pummerer reaction, yielding protected a-hydroxy aldehydes tScheme 20.8) that upon acidic treatment afforded 3-substituted ribofuranoses. 

When the reaction was canied out in aqueous methanol as the solvent, hexyl bromide was converted to hexyl cyanide in 71% yield by heating with sodium cyanide. Although this is a perfectly acceptable synthetic reaction, a period of over 20 hoars was requited. Changing the solvent to dimethyl sulfoxide brought about an increase in the reaction rate... 

The oxidation of sulfides to the corresponding sulfoxides and sulfones proceeds under rather strenuous conditions requiring strong oxidants such as nitric acid, hydrogen peroxide, chromic acid, peracids, and periodate. Using MW irradiation, this oxidation is achievable under solvent-free conditions and with desired selectivity to either sulfoxides or sulfones using 10% sodium periodate on silica (Scheme 6.34)... 

In 1967 Cava and Pollack obtained derivatives of the fourth, so-called nonclassical , thienothiophene— thieno[3,4-c]thiophene (4), a condensed heterocycle with formdly tetracovalent sulfur (42)j. The reaction of 3,4-bischloromethyl-2,5-dimethylthiophene (141) with sodium sulfide afforded 4,6-dimethyl-lif,3ff-thieno[3,4-c]thiophene (142) periodate oxidation of 142 gave die corresponding sulfoxide (143) in 91% yield. Attempts to convert the sulfoxide (143) into the thieno-[3,4-c]thiophene by the method used for S3mthesizing benzo[c]-thiophene led only to polymer. However, 24% of adduct 144 and 10% of 145 were obtained by refluxing sulfoxide (143) with N-phenylmaleimide in acetic anhydride, indicating that the thieno[3,4-c]-thiophene was formed as an intermediate. 

Reduction of the furan (152) with sodium borohydride gave diol 154 and its cyclization (P2SJ/CS2) formed 19% of sulfide (155). Periodate oxidation of 155 gave (92%) the corresponding sulfoxide (156). The latter reacted with dimethyl acetylenedicarboxylate forming the adduct 157 (70%) the formation of 157 is evidence of the presence of the thieno[3,4-c]furan system (158) as an intermediate. Cyclization of diketone 153 in the presence of phosphorus pentasulfide proceeds M. P. Cava and M. A. Sprecker, J. Amer. Chem. Soc. 94, 6214 (1972). 

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