Electrophilic acetylene equivalents

Stang PJ (1995) Alkynyliodonium Salts Electrophilic Acetylene Equivalents. In Stang PJ, Diederich F (eds) Modern Acetylene Chemistry. VCH, Weinheim, p 67, chap 3... 

The great majority of o-acetylide transition metal complexes are prepared by interaction of a metal halide with acetylide, RC C", or the formal oxidative addition of terminal alkynes or alkynyl stannanes to the metal center. As amply demonstrated in the previous section, alkynyliodonium salts may serve as electrophilic acetylene equivalents. In other words, transition metal complexes may act as nucleophiles in reactions with alkynyliodonium species. Indeed, the reaction [81] of the square planar Vaska s complex, 106, and its Rh analog, 107, with a variety of alkynyliodonium triflates in toluene results in 89-96% isolated yield of the hexa-coordinate o-acetylide complexes, 108 and 109 [Eq. (58)]. Reaction is essentially instantaneous and occurs with retention of stereochemistry around the metal center. 

Trimethylsilylalkynes can be converted to alkynyl(phenyl) iodonium triflates by treatment with PhI(OAc)2 and Tf20 (eq 88). Alkynyl(phenyl)iodonium triflates are useful electrophilic acetylene equivalents and can act as Michael acceptors, 1,3-dipolariphiles and alkynyl cation equivalents. ... 

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