Epoxides with dimethyl sulfoxide

The maiin domain of oxidation with dimethyl sulfoxide is the conver-sionofprimary alcoholsinto aldehydes andofsecondaryalcoholsintoketones. These reactions are accomplished under very mild conditions, sometimes at temperatures well below 0 °C. The reactions require the presence of acid catalysts such as acetic anhydride [713, 1008, 1009], trifluoroacetic acid [1010], trifluoroacetic anhydride [1011, 1012, 1013], trifluorometh-anesulfonic acid [1014], phosphoric acid [1015, 1016], phosphorus pentox-ide [1006, 1017], hydrobromic acid [1001], sulfur trioxide [1018], chlorine [1019, 1020], A -bromosuccinimide [997], carbonyl chloride (phosgene) [1021], and oxalyl chloride (the Swem oxidation) [1022, 1023, 1024], Dimethyl sulfoxide also converts sufficiently reactive halogen derivatives. into aldehydes or ketones [998, 999] and epoxides to a-hydroxy ketones at -78 °C [1014]. 

The oxidative cleavage of epoxides with hydrogen peroxide gives vicinal hydroxy hydroperoxides [178]. With dimethyl sulfoxide in the presence of trifluoromethanesulfonic acid and diisopropylethylamine, epoxides are converted into a-hydroxy ketones [1014], and with periodic acid, dicarbonyl compounds are formed [761] (equations 343 and 344). 

Oxidation of an alkene with a peroxyacid leads to an epoxide, with a carboxylic acid as the by-produet 18,37,38,40,42,44, 51. Oxidative cleavage of an alkene with ozone leads to an ozonide. Reductive workup with dimethyl sulfoxide or zinc and acetic acid gives ketones and/or aldehydes. Oxidative workup with hydrogen peroxide gives ketones and/or earboxylic acids 19,20, 21, 22,36,39,41,44. 

Solvolysls of oxiranes with dimethyl sulfoxide and 2,4,6-trlnltro-benzenesulfonlc acid affords threo-glyools from ois-epoxides and... 

A mixture of the epoxide ca. 5 mmol), sodium azide (6 g, activated by the method of Smith) and 0.25 ml of concentrated sulfuric acid in 70 ml of dimethyl sulfoxide is heated in a flask fitted with a reflux condenser and a drierite tube on a steam bath for 30-40 hr. (Caution carry out reaction in a hood.) The dark reaction mixture is poured into 500 ml of ice water and the product may be filtered, if solid, and washed well with water or extracted with ether and washed with sodium bicarbonate and the water. The crude azido alcohols are usually recrystallized from methanol. 

The hydrolysis of epoxides is a convenient method for the preparation of vie-diols. The reaction is catalyzed by acids or bases (see discussion of the mechanism on p. 369). Among acid catalysts the reagent of choice is perchloric acid, since side reactions are minimized with this reagent.500 Dimethyl sulfoxide is a superior solvent for the alkaline hydrolysis of epoxides.501 OS V, 414. 

Organocopper reagents, 207 of cyclopropanes Dimethyl sulfoxide, 124 Lead tetraacetate, 155 of epoxides (see also Rearrangement reactions, Reduction reactions) with organocopper reagents... 

Ylides based upon sulfur are the most generally useful in these cyclopropane-forming reactions.133 Early work in this area was done with the simple dimethyloxysulfonium methylide (9) derived from dimethyl sulfoxide. The even simpler dimethylsulfonium methylide (10) was studied at the same time as a reagent primarily for the conversion of carbonyl compounds into epoxides.134 Somewhat later, other types of sulfur ylides were developed, among which the nitrogen-substituted derivatives such as (11) are... 

A new parameter space for the synthesis of silsesquioxane precursors was defined by six different trichlorosilanes (R=cyclohexyl, cyclopentyl, phenyl, methyl, ethyl and tert-butyl) and three highly polar solvents [dimethyl sulfoxide (DMSO), water and formamide]. This parameter space was screened as a function of the activity in the epoxidation of 1-octene with tert-butyl hydroperoxide (TBHP) [26] displayed by the catalysts obtained after coordination of Ti(OBu)4 to the silsesquioxane structures. Fig. 9.4 shows the relative activities of the titanium silsesquioxanes together with those of the titanium silsesquioxanes obtained from silsesquioxanes synthesised in acetonitrile. The values are normalised to the activity of the complex obtained by reacting Ti(OBu)4 with the pure cyclopentyl silsesquioxane o7b3 [(c-C5H9)7Si7012Ti0C4H9]. 

Mildly basic conditions can be provided using quaternary ammonium fluorides with aqueous hydrogen peroxide in dimethyl sulfoxide solution. For example, carvone gives 82% epoxide in six hours at room temperature. The method is particularly suited to base-sensitive substrates such as cinnamalde-hyde.65... 

Reaction with epoxides. Dimethyl sulfoxide and a strong acid (2,4,6-trinitro-bcnzcncsulfonic acid, TNBSA, was used) reacts with epoxides (1) to form alkoxy-sulfonium salts (2) in good yield. Since hydrolysis of alkoxysulfonium salts proceeds exclusively by attack at sulfur, the reaction provides a stereospecific synthesis of 1,2-glycols. Thus the reaction of lis- and rrans-9,10-epoxystearic acids with DMSO-... 

This stabilized ylide reacts with aldehydes and ketones to furnish epoxides. The difference in reactivity between dimethylsulfonium methylide and dimethyloxosulfo-nium methylide is apparent when considering their reactions with a, 3-unsaturated ketones. Whereas the nonstabilized ylide yields the epoxide, the stabilized ylide affords a cyclopropane via conjugate addition followed by ring closure and loss of dimethyl sulfoxide. 

Acyloins are sometimes formed in moderate yield when 1,2-disubstituted epoxides are treated with BFj in dimethyl sulfoxide solvent. A curious report of highly temperature dependent nonoxidative rearrangement of 2,3-epoxycyclododecanone indicates that a 1,2-dione is formed at 85 °C, whereas a 1,3-dione is the product at 150 °C. All of these applications require heating, since the Lewis acidity of BF3 is strongly attenuated in dimethyl sulfoxide. O ... 

Dimethyl sulfoxide-derived reagent (c). Dimethyloxosulfonium methylide, (C H. i)2S=C H 2. This more stable reagent introduced by Corey reacts with monofunctional carbonyl compounds to give epoxides (oxiranes), but with a,/3-unsaturated ketones it gives cyclopropyl ketones. In one procedure a mixture of 0.1 mole each of powdered sodium hydride and trimethyloxosulfonium iodide (I) - is placed in a three-... 

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