Bis-iodonium ethyne

A number of interesting bis-iodonium acetylenes and bis-iodonium diynes were reported in the early 1990s. Reaction of bis-tin-acetylene 29 and bis-tin-diyne 31 with two equivalents of 7 in cold dichloromethane results in the formation of novel bis-iodonium ethyne 30 [24] and bis-iodonium diyne 32 [39], respectively [Eqs. (15), (16)]. 

Scheme 3-10 Diels-Alder cycloaddition of bis-iodonium ethyn 30, with cyclopentadiene and furans and subsequent reaction of the adducts.

Likewise, this methodology is well suited for the preparation of novel bis(iodonium)ethyne (24) (equation 8) as well as bis(iodonium)diynes (25-27). This procedure is also applicable to the preparation of buta-l,3-diynyl(phenyl)iodonium trifiates (28) (equation 9). The use of iodosyl trifiate (29) and two equivalents of silylacetylene affords the dialkynyliodonium salts (30) (equation 10). ... 

Diels-Alder reactions of alkynyl(phenyl)iodonium triflates (i.e. containing electron-withdrawing groups in the alkynyl moiety) and [bis(phenyliodonium)] ethyne ditrifiate have been employed for the synthesis of cyclic vinyliodonium salts (equations 143 and 144)17,41. The availability of such compounds offers considerable potential for the elaboration of densely functionalized cyclic molecules. 

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