Sulfides, 0-hydroxy oxidation

The reagent was used by Corey and Kim in an improved synthesis of prostaglandins. Thus oxidation of the hydroxy acid (5) to the keto acid (6) was effected in > 90% yield with ase of N-cblorosuccinimide-dimethyl sulfide. The oxidation had been carried out previously with Jones reagent at —20° in about 70% yield. The carboxyl function... 

Oxidation of sulfides. This oxide in combination with bromine has been used for selective oxidation of a secondary alcohol in the presence of a primary alcohol (7, 26 27). This mild procedure is also applicable to oxidation of sulfides (o sulfoxiilcs without further oxidation to sulfones (equation I). The method can also be used lo oxidi/c hydroxy sulfides to keto sulfoxides in one operation. The reageni also can be used lor oxidation of sidfenamides to sulfinamidcs without loi II union of sn I Iona in ides (eipial ion II). ... 

Chloro- and 2-acetamido-5-sulfide derivatives are readily oxidized to the corresponding sulfones, while curiously enough 2-hydroxy-5-arylsulfides are reported to be stable to oxidation (228, 55 )-... 

Attempts to oxidize 5-(2-hydroxy thiazo]yl)phenyl sulfides are reported to be unsuccessful (228). 

Electron-deficient alkenes add stereospecifically to 4-hydroxy-THISs with formation of endo-cycloadducts. Only with methylvinyl-ketone considerable amounts of the exo isomer are produced (Scheme 8) (16). The adducts (6) may extrude hydrogen sulfide on heating with methoxide producing 2-pyridones. The base is unnecessary with fumaronitrile adducts. The alternative elimination of isocyanate Or sulfur may be controlled using 7 as the dipolarenOphile. The cycloaddition produces two products, 8a (R = H, R = COOMe) and 8b (R = COOMe, R =H) (Scheme 9) (17). Pyrolysis of 8b leads to extrusion of furan and isocyanate to give a thiophene. The alternative S-elimi-nation can be effected by oxidation of the adduct and subsequent pyrolysis. 

The reaction with sodium sulfite or bisulfite (5,11) to yield sodium-P-sulfopropionamide [19298-89-6] (C3H7N04S-Na) is very useful since it can be used as a scavenger for acrylamide monomer. The reaction proceeds very rapidly even at room temperature, and the product has low toxicity. Reactions with phosphines and phosphine oxides have been studied (12), and the products are potentially useful because of thek fire retardant properties. Reactions with sulfide and dithiocarbamates proceed readily but have no appHcations (5). However, the reaction with mercaptide ions has been used for analytical purposes (13)). Water reacts with the amide group (5) to form hydrolysis products, and other hydroxy compounds, such as alcohols and phenols, react readily to form ether compounds. Primary aUphatic alcohols are the most reactive and the reactions are compHcated by partial hydrolysis of the amide groups by any water present. 

Hydrogen Sulfide andMercaptans. Hydrogen sulfide and propylene oxide react to produce l-mercapto-2-propanol and bis(2-hydroxypropyl) sulfide (69,70). Reaction of the epoxide with mercaptans yields 1-aLkylthio- or l-arylthio-2-propanol when basic catalysis is used (71). Acid catalysts produce a mixture of primary and secondary hydroxy products, but ia low yield (72). Suitable catalysts iaclude sodium hydroxide, sodium salts of the mercaptan, tetraaLkylammonium hydroxide, acidic 2eohtes, and sodium salts of an alkoxylated alcohol or mercaptan (26,69,70,73,74). 

Procedure 2 Oxidation of jS-Hydroxy Sulfides to yS-Hydroxy Sulfoxides Catalyzed by CHMO... 

Table 11.2 Oxidation of racemic (3-hydroxy sulfides catalyzed by CHMO...

The kinetic resolution of /3-hydroxy sulfides mediated by CHMO provides an excellent result in the case of sulfide ( )-2 and moderate results with ( )-l and ( )-3. Indeed, the enzyme-catalysed oxidation to sulfoxide 2a showed remarkable enantio- and diastereo-selectivity with an enantiomeric ratio E of 299 and with an ee > 98 % (C = 47 %). 

Steric effects dominate in the oxidation of dialkyl, alkyl phenyl and benzal methyl phenyl sulfides to their sulfoxides by quinolinium fluorochromate (QFC) in aqueous acetic acid. QFC oxidation of phenoxyacetic acids has been smdied. Imidazolium dichromate oxidations of a-hydroxy acids have been smdied. ... 

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