Tertiary Selenonium and Telluronium Ions

Methylation of trifluoromethylphenylselenide under conditions shown in Eq. (4.81) was successfully employed in the synthesis of Me(CF3)PhSe+BF4. 278 The cyclization methods described in Eq. 4.45 have also been used to prepare analogous Se and Te derivatives175 [Eq. (4.83)]. 

Kataoka and co-workers have developed methods to obtain alkynyl- and alkenyl-selenonium ions279 280 [Eq. (4.84)] and allenylselenonium triflate derivatives.281 

Various organoselenium compounds are able to add in stereospecific anti fashion to alkenes282 [Eq. (4.85)]283 or alkynes282 [Eq. (4.86)] to form stable cyclic selenonium ions. 

The synthesis and detailed H, 13C, 77Se, and 125Te NMR spectroscopic characterization of the corresponding triflates have been reported by Laali et al 275 The 77 Se 

1-Alkynylphenyliodonium tetrafluoroborates selectively transfer the unsaturated group to diphenyl chalcogens to form 1-alkynyldiphenyIonium ions290 

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