Selenium compounds reactions with arynes

Reactions of phosphines and phosphites have received some attention but their preparative value is limited. The zwitterion formed from diphenylmethylphosphine and benzyne rearranges to ylide (124) which can be captured by Wittig alkenation, with cyclohexanone, in about 20% yield.159 Some synthetically useful reactions of tellurium and selenium compounds with arynes have been reported. For example, heating diphenyl iodonium carboxylate and bis(p-ethoxyphenyl) ditelluride in dichlorobenzene affords the compound (125).160 The corresponding reactions with diphenyl selenide and diphenyl sulfide... 

The most useful procedure for the preparation of early transition metal complexes of type 13 is the thermal elimination of benzene or methane from diphenyl or arylmethyl compounds,respectively (12 and 14 in Scheme 1) [5-9]. At the end of the 1960s, the first studies of the reactivity of such a complex, specifically the aryne-titanocene complex 15, showed that it reacts with species such as alkynes, CO2, N2 or selenium to form titanacycles [7]. Particularly interesting for the aim of this chapter is the insertion of alkynes to form titana-cyclopentadienes 16. This reaction takes place in moderately good yields with both electron-rich and electron-poor alkynes (Scheme 2) [13-15]. 

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