Sulfoxide from sulfides

The synthesis of sulfoxides from sulfides has been widely explored, and numerous oxidants have been investigated to achieve an efficient and selective sulfoxidation [38]. However, most of the reagents require carefully controlled conditions, including the quantity of oxidants, to avoid the formation of sulfone side products. Control to avoid formation of sulfones is particularly difficult since the first oxidation to sulfoxides requires relatively high energy [38]. m-Chloroperbenzoic acid (mCPBA) has been intensively used in the synthesis of prazole derivatives [39]. 

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... 

Another argument against the oxo-transfer mechanism in our catalytic aerobic oxidation protocol is the lack of formation of sulfoxides from sulfides, N-oxydes from amines and phosphine oxydes from phosphines. Alkenes also proved to be inert towards oxidation no epoxide formation could be detected under our reaction conditions. 

Remarkably, there is a noticeable lack of general methods for the asymmetric preparation of chiral sulfoxides from sulfides. The most satisfactory method would be a generally applicable enantioselective sulfoxidation reaction which would allow the preparation of sulfoxides from any prochiral sulfide with high ee s and in which the sulfoxide would be amenable to enantioselective preparation in both senses. 

A variety of other oxidants that produce sulfoxides from sulfides are known, such as nitric acid, acyl nitrates, nitronium salts,N204, oxygen with ruthenium complex catalysts, - pressurized oxygen with CAN as a catalyst, ozone, - TTN, Ce salts, - and potas-... 

Organic hydroperoxides are generally used for the preparation of sulfoxides from sulfides, - while sulfones can be obtained in neutral organic solvents in the presence of metal catalysts such as V, Mo and Ti oxides at 50-70 C. Two polymer-supported reagents which involve peroxy acid groups and bound hypervalent vanadium(V) and molybdenum(VI) compounds have been developed for facile oxidation of sulfoxides to sulfones. 

Mata, E. G. Recent advances in the synthesis of sulfoxides from sulfides. Phosphorus, Sulfur Silicon Relat. Elem. 1996,117, 231-286. 

From Amberlyst A-26 0H form by treatment with aq. HIO4 soln.208 From Amberliie IRA 904 cr form by treatment with aq. NalOj soln. 0 Oxidative cleavage of 1,2-diols. - Quinones by oxidation of quinols. Sulfoxides from sulfides (in MeOH).-< Other transformations azobenzene from hydrazo-benzene. nitrosocarbonylbenzene from bcnzohydroxamic acid. ... 

Other classical oxidizing reagents for the sulfur-sulfoxide oxidation [132] were tested, and they nearly all gave the expected products but often without any control of the stereochemistry. Only Oxone which has been used for the formation of sulfoxides from sulfides [133, 134] gave an interesting result. Oxone is acidic and formed a water soluble salt with 26-diethylaminoethylthio pristinamycin Ilg (94a) and the oxidation, which could be carried out in water or aqueous ethanol between —20° and 5°, afforded in good yield a 95 5 mixture of the corresponding diastereomeric sulfoxides [135]. 

One reported method describes the convenient use of sodium metaperiodate as an oxidizing agent to form sulfoxides from sulfides free of... 

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