Sulfones dimethyldioxirane

Butyl hypochlorite, 55 of phenols to quinones Benzoyl /-butyl nitroxide, 28 2,3-Dichloro-5,6-dicyano-l, 4-benzoqui-none, 104 Periodic acid, 238 of phosphorus compounds Dimethyldioxirane, 120 of selenium compounds Potassium permanganate, 258 of sulfides to sulfoxides and sulfones /-Butyl hydroperoxide-Dialkyl tar-trate-Titanium(IV) isopropoxide, 51 ra-Chloroperbenzoic acid, 76, 112 Dimethyldioxirane, 120 of thiols to sulfur compounds Trimethylsilyl chlorochromate, 327... 

Chemical shift data (toluene-r/8) for the sulfoxides and sulfones obtained from the oxidation of 3-arylide-nethiochroman-4-ones using dimethyldioxirane are shown in Table 9 <2003MRC193>. 

Stable sulfones have been obtained from oxidation of 2,5-dimethylthiophene and benzo[A]thiophene with dimethyldioxirane. Trifluoroperacetic acid in MeCN in the absence of water is an effective reagent for the oxidation of thiophenes bearing electron-withdrawing groups to the corresponding thiophene 1,1-dioxides <2001TL4397>. 

Determination of dimethyldioxirane concentration by the GLC method is as follows A standard solution of thioanisole (phenyl methyl sulfide) is prepared. The solution is usually 0.2 M in acetone, but other concentrations may be used. It is important to keep the sulfide in excess so that oxidation by the dioxirane will produce largely or exclusively the sulfoxide and not the sulfone. 

A useful conversion of a nucleoside 2,6-dithione into a 6-methylamino-adenosine via oxidation with dimethyldioxirane, illustrates several instructive points. The presumed intermediates are sulfinic acids the 2-sulfinic acid loses sulfur dioxide to leave hydrogen at C-2, and nucleophilic displacement of the 6-sulfinic acid (or possibly the sulfonic acid after further oxidation) introduces the amino group. Similar reactions can be carried out on pyrimidine thiones. The scheme shows intermediates derived from a disulfinic acid - it is not clear in what order oxidations/loss of sulfur dioxide/displacements take place. 

Another set of tribenzotriquinacenes functionalized at the peripheral bridgehead positions is shown in Scheme 32. The triamines 162 and 163 were obtained in excellent yield by aminolysis of the methyltribenzotriquinacene 142 with ammonia and dimethylamine, respectively, in benzene solution [100]. Solvolysis of 142 in the neat alkyl (R = Me, Et, Pr, nBu) and benzyl mercaptane gave the three-fold thioethers 164 and 165 [106]. Oxidation of these compounds with raeta-chloroperbenzoic acid (MCPBA) led to complete decomposition [98], whereas use of dimethyldioxirane gave high yields of the tris(sulfones) 166 and 167 as thermally stable compounds [106]. 1H- and 13C-NMR spectrometry as well as X-ray structural analysis revealed the dynamic behaviour of the sulfones,... 

Oxidation of Sulfur Functional Groups. Dimethyldioxirane rapidly oxidizes sulfides to sulfoxides and converts sulfoxides to sulfones (eq 25). The partial oxidation of sulfides to sulfoxides can be controlled by limiting the quantity of DDO. Since Oxone is one of the many reagents that can perform these reactions, the extra effort involved in preparing DDO solutions is often not warranted. An exception involves the transformation of thiophenes to the corresponding sulfones (eq 26). A similar procedure gives a-0x0 sulfones by DDO oxidation of thiol esters (eq 21)P... 

The cleavage of heteroaryl sulfones from polymeric supports can be achieved by reaction with azide ions. Suckling el al. applied this strategy to the synthesis of pteridines. In fact, the starting pyrimidine was linked to polystyrene via a thioether 214. After con-stmction of the pteridine ring system, the activation of the sulfur linker by oxidation to the sulfone with dimethyldioxirane followed by nucleophilic substitution with sodium azide affords the target molecule 218 in 41% overall yield (Scheme 3.30). 

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