Sulfones osmium tetroxide

Selective hydroxylation with osmium tetroxide (one equivalent in ether-pyridine at 0 ) converts (27) to a solid mixture of stereoisomeric diols (28a) which can be converted to the corresponding secondary monotoluene-sulfonate (28b) by treatment with /7-toluenesulfonyl chloride in methylene dichloride-pyridine and then by pinacol rearrangement in tetrahydrofuran-lithium perchlorate -calcium carbonate into the unconjugated cyclohepte-none (29) in 41-48 % over-all yield from (27). Mild acid-catalyzed hydrolysis of the ketal-ketone (29) removes the ketal more drastic conditions by heating at 100° in 2 hydrochloric acid for 24 hr gives the conjugated diketone (30). 

Osmium tetroxide is another chemoselective oxidant repotted to yield sulfones frtxn sulfoxides. Thus, treatment of a mixture of diphenyl sulfide and sulfoxide with OSO4 in boiling ether for 48 h affords di-... 

Sodium permanganate and, especially, osmium tetroxide oxidize sulfoxides to sulfones but do not oxidize sulfides [837]. When a mixture of equimolar amounts of diphenyl sulfide, diphenyl sulfoxide, and osmium tetroxide is refluxed in ether for 48 h, the sulfoxide is oxidized in 96% yield to the sulfone, whereas the sulfide is completely recovered [837], Certain unsaturated sulfoxides treated with a catalytic amount of osmium tetroxide and trimethylamine oxide as a reoxidant are not only oxidized to sulfones but also hydroxylated at the double bond. The sulfoxide group exerts a steric influence in the hydroxylation two stereoisomers of a sulfoxide yield, by syn hydroxylation, two different stereoisomeric diols (equation 580) [1102]. 

The hrst example is relevant to the zaragozic acids field. As shown in Scheme 11.34, ketone 71 was treated with methyl triphenylphosphoranylidene acetate to give the Z olefin 130. Osmium tetroxide dihydroxylation of the latter gave the two possible diols with 131 as the major product. Problems arose in the attempted formation of the required 2,8-dioxabicyclo[3.2.1]-octane, possibly because of the presence of the carboxy residue. Only 1,5-anhydro derivatives were formed upon transacetalation of 131 and 132. Thus, allylic derivative 133, synthesized by the same route, was submitted to dihydroxylation and gave a mixture of diols. In this case, upon treatment with p-toluene sulfonic acid, the diol 134 gave the expected ring system 135. These synthetic smdies illustrate the inherent problematic nature associated with synthetic approaches to zaragozic acids [108]. 

Sulfur compounds. Sulfides are inert to osmium tetroxide but are oxidized rapidly by ruthenium tetroxide at 0° to sulfoxides, which in turn are oxidized by the reagent to sulfones. ... 

Carretero and co-workers found that dqjrotection and cyclization of the vinyl-sulfone 294 produced a 4 1 mixture of 2,3-cu-disubstituted pyrrolidine 295 and its tram isomer (Scheme 40). A/-Alkylation of the nuxture. with 3-chloro-2-chloro-methylprop-l-ene followed by chromatogttqjhy led to isolation of the pure 2,3-c/s product 296, silylation and base-initiated cyclization of which gave indolizidine 297. Ozonolysis and elimination of the sulfone group yieldied another pivotal intermediate, the bicyclic enone 298. Reduction with L-Selectride afforded an inseparable nuxture of two diastereomeric alcohols 299 (9 1). Separation was accomplished only after dihydroxylation with osmium tetroxide and peracetylation of the resdting tetrols. The synthesis of ( )-241 was completed by hyc lysis of the m or tetraacetate 300. 

Sulfur compounds [1, 988, after citation of ref. 4], The statement that sulfides are inert to osmium tetroxide is not entirely correct. Some sulfides (e.g., diphenyl sulfide and dibenzyl sulfide) are inert, but thiacyclohexane, S(CH2)5, is converted into the sulfone 02S(CH2)5 in 58% yield on treatment with osmium tetroxide at—15° for 2 hrs.40... 

Cyclic sulfonamides are Lermed sultams. From the enantiomeric 10-camphorsulfonic acids, both enantiomers of camphorsultam (49) are readily available by reduction of the intermediate sulfon-imide 484fi 50 and are commercially available. They have been used for the formation of amides with unsaturated acids, which are useful chiral dienophiles and dipolarophiles (Sections D. 1.6,1.1.1- and D. 1.6.1.2.1.) or undergo osmium tetroxide catalyzed dihydroxylations (Section D.4.4.). Other amides may be used for enolate reactions (Sections D.1.1.1.3.1., D.l.5.2.1. and D.4.3.). The. V-fluorinated derivative was obtained by direct fluorination of the sultam with 10% fluorine in nitrogen at low temperature5 , and has been used for the enantioselective formation of C —F bonds (Section D.3.). 

Osmium tetroxide also catalyzes the oxidation of organic sulfides to sulfones with NMO or trimethylamine iV-oxide (see Osmium Tetroxide-N-MethylmorphoUne N-Oxide). In contrast, most sulfides are not oxidized with stoichiometric amounts of OSO4. Oxidations of alkynes and alcohols with OSO4 without and in the presence of cooxidants have also been reported. However, these reactions have not found wide synthetic applications because of the availability of other methods. 

OSA n-OSA. See Octenylsuccinic anhydride OSBP. See o-s-Buty I phenol Osimol DR, Osimol SF. See Sulfonic acid OS/ Specialties LE-45 Series. See Polydimethylsiloxane Osmic acid. See Osmium tetroxide Osmium... 

Sulfones are valuable intermediates for the synthesis of chemically and biologically useful molecules. Traditionally, they are prepared by oxidation of sulfides with nitric acid, KMnO, MnO, NaClO, m-chloroperbenzoic acid, sodium metaperiodate, bromine, dinitrogen tetraoxide, oxaziri-dine, benzeneseleninic peracid, tert-butyl hydroperoxide, sulfinyl peroxy compounds, iodosobenzene diacetate and 4-methylmorpholine N-oxide/ osmium tetroxide. 

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