No abstract

A system aluminum (and titanium) tert butoxide-tert butyl hydroperoxide (1 : 2) under mild conditions (20 °C, 1 h) oxidizes aliphatic and alkylaromatic sulfides and diphenyl sulfide to the corresponding sulfones in yields close to ~100%. The oxidation is induced by electron excited dioxygen formed upon thermal decomposition of intermediate metal containing peroxy trioxides (ozonides). The latter are formed as a result of the reversible reaction of aluminum or titanium tert butoxides with tert butyl hydroperoxide followed by the interaction of di tert butoxy tert butylperoxyaluminum and tri tert butoxy tert butylperoxytitanium that formed with another Bu t OOH molecule. Aluminum containing peroxide (Bu t O) 2 AlOOBu t oxidizes sulfides to sulfoxides.

Methyl phenylethynyl and phenyl phenylethynyl sulfides are selectively converted into methyl phenylethynyl and phenyl phenylethynyl sulfones, respectively, under the action of system tert butyl hydroperoxide-aluminum tri tert butoxide in benzene at 20 °C. The analo gous oxidation of diphenyl disulfide results in S phenyl benzenethiosulfonate.Key words: oxidation, aluminum tri tert butoxide, tert butyl hydroperoxide, activated di oxygen, alkynyl sulfides, sulfones, diphenyl disulfide, S phenyl benzenethiosulfonate.Sulfides and their oxygen containing derivatives, sul foxides and sulfones, are incorporated in natural organic compounds and polymers and widely used in different fields. 1 The sulfones are usually obtained by the oxidation of initial sulfides with organic peroxy acids, in particular, m chloroperbenzoic acid. The reactions occur in two steps: first, sulfides are converted into sulfoxides, which then transform into sulfones at 20 °C with high yields. Current ly, catalytic systems based on 30% hydrogen peroxide in water soluble solvents in the presence of derivatives of transition metals, for example, titanium 2,3 and vanadi um 2,4-6 compounds are often used in the synthesis of sulfones. It is of note that such catalytic systems allow high conversion degrees (>90%), however, it is difficult to accomplish the process selectively.In the present study, we offer a single step preparative method for the synthesis of phenylethynyl sulfones by ox idation of the respective sulfides under the action of the system Bu t OOH-(Bu t O) 3 Al. It was earlier shown 7,8 that the latter oxidizes dialkyl, dibenzyl, and diphenyl sulfides to sulfones in virtually quantitative yields. The oxidant is the dioxygen formed in successive reaction of two moles of tert butyl hydroperoxide with aluminum tert butoxide in benzene or CCl 4 and located in the coordination sphere of the Al atom.The aim of the present work was to study the oxidation of sulfides containing the phenylethynyl fragment under the action of the system Bu t OOH-(Bu t O) 3 Al.The oxidation of methyl phenylethynyl sulfide (1a) and phenyl phenylethynyl sulfide (1b) containing the alky nyl group at the S atom with the Bu t OOH-(Bu t O) 3 Al system results in the respective sulfones 2a,b (Scheme 1).The reactions were carried out at a molar ratio subst rate : Bu t OOH : (Bu t O) 3 Al = 1 : 2 : 1 (benzene, 20 °C), i.e., under the conditions comparable to those described earlier. 7 The oxidation occurs at the sulfur atom of the sulfides, the yields of sulfones 2а,b are 92% and 47%, respectively. According to GLC data, in the case of com pound 1a, ∼50% of the starting sulfide is converted into sulfone 2a already in 50 min after the mixing of compo nents, and after 20 h the reaction is fully completed.The oxidation of compound 1b under analogous con ditions is also completed in 24 h, but it occurs substantial ly more slowly, and sulfone is formed in lower yield: after 1 h, compound 2b was not observed in the reaction mix ture, only after 3.5 h the yield of the sulfone reache...