Sulfoxides sodium periodate

Sodium periodate Sulfoxides from thioethers s. 31, 971 NalOt >S >SO... 

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... 

Oxidation of Sulfides to Sulfoxides and Sulfones - Sodium Periodate-Silica... 

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)... 

Rj = PhCH2 R2 = Ph Rj = Ph, n-C12ttz R2 = Me Scheme 6.34 Oxidation of sulfides to sulfoxides and sulfones by silica-supported sodium periodate. 

Oxidation of the heterocycles with common reagents such as MCPBA, sodium periodate or hydrogen peroxide cleanly affords the sulfoxides and sulfones, and it is clear that the sulfur atom is the principal centre of reaction for electrophiles. While the sulfone is a quite inert functionality, the sulfoxides may be reduced to the sulfides with phosphorus pen-tasulfide as for the tetrahydro systems (78CJC1423). Positive halogen sources likewise react at sulfur, and the intermediate sulfonium halide rearranges, usually by 1,2-shift to the a-halo product. 

For less reactive thiazines sodium periodate or 3-chloroperbenzoic acid are suitable reagents for sulfoxide synthesis but it is not always possible to prevent over-oxidation and the formation of the corresponding sulfone (75JCS(P1)716>. Carbonyl substituents at C-6... 

To a cooled solution of dithiane (1) (2.00 g, 16.7 mmol) in methanol (125 ml) was added an aqueous solution (35 ml) of sodium periodate (3.68 g, 17.5 mmol) at such a rate (approximately 30 min) to maintain the temperature at 20°C. Stirring and cooling were continued for an additional 30 min. The reaction mixture was then filtered to remove sodium iodate, and the resulting solution taken to near dryness on a rotary evaporator. Extraction of the solids with chloroform produced a solution which was dried over sodium sulfate, and filtered. Evaporation left the crystalline sulfoxide (2) (2.13g, 94%), m.p. 86-87°C. 

The present procedure is a specific example of the method generalized by Leonard and Johnson.8 The method employs extremely mild reaction conditions and affords high yields of sulfoxides (Note 9) free of contamination by sulfides or sulfones. Sodium periodate is easily and safely handled however, the higher cost of this reagent in comparison to certain other oxidants, e.g., hydrogen peroxide, may prohibit its use in large-scale reactions. 

On the pages which follow, general methods are illustrated for the synthesis of a wide variety of classes of organic compounds including acyl isocyanates (from amides and oxalyl chloride p. 16), epoxides (from reductive coupling of aromatic aldehydes by hexamethylphosphorous triamide p. 31), a-fluoro acids (from 1-alkenes p. 37), 0-lactams (from olefins and chlorosulfonyl isocyanate p. 51), 1 y3,5-triketones (from dianions of 1,3-diketones and esters p. 57), sulfinate esters (from disulfides, alcohols, and lead tetraacetate p. 62), carboxylic acids (from carbonylation of alcohols or olefins via carbonium-ion intermediates p. 72), sulfoxides (from sulfides and sodium periodate p. 78), carbazoles... 

Keywords sulfide, sodium periodate, wet silica, microwave irradiation, sulfoxide... 

The sulfide 1 (0.75 mmol) is dissolved in dichloromethane (2-3 mL) and adsorbed over silica supported sodium periodate (20%, 1.36 g, 1.28 mmol) that is wetted with 0.3 mL of water by thoroughly mixing on a vortex mixture. The adsorbed powdered material is transferred to a glass test tube and is inserted in an alumina bath (alumina 100 g, mesh 65-325, Fisher scientific bath 5.7 cm diameter) inside the microwave oven. The compound is irradiated for the time specified in the table and the completion of the reaction is monitored by TLC examination. After completion of the reaction, the product is extracted into ethyl acetate (2x15 mL). The removal of solvent at reduced pressure affords crude sulfoxide 2 that contains less than 5% sulfone. The final purification is achieved by column chromatography over silica gel column or a simple crystallization. 

Selective oxidation of sulfides to sulfoxides and sulfones was achieved over sodium periodate (NaI04) on silica (20%), under solvent-free conditions to afford either sulfoxides or sulfones as desired (Scheme 5) [49]. 

Alkylthio)pyridines can also be oxidized to sulfoxides using sodium periodate in methanol <2002SL1404> or MCPBA in dichloromethane <2001TL8845>. 

Several l,3-dihydrobenzo[c]thiophenes have been oxidized to the corresponding sulfoxides (Table VI) with peracetic acid,43,44 /-butyl hydroperoxide,9 sodium periodate in aqueous ethanol,52,55,56 or... 

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. 

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. 

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. 

This Dod-S-Me recovered from the reaction can be reoxidized to dodecyl methyl sulfoxide by sodium periodate. 

---