Alkenyl triflones

Alkenyl triflones. This reagent, CF3S02SPh, as well as CFjS02SePh, react with alkenes at 80°, and the adducts undergo elimination on oxidation. 

Alkenyl triflones The fZ>alkenyl triflones can be made from alkynyl triflones by the addition of HI followed by StUle coupling. Some other alkenyl triflones are available from organocopper reactions. 

Alkenyl triflones have unusual reactivities. A stereoselective synthesis of trisubstituted alkenyl triflones involves the organocoppers and alkynyl triflones. 

In a series of papers, Fuchs has reported allylation [104], alkenylation [105, 106] and alkynylation [107-110] of C-H bonds. All these processes are based on the radical -fragmentation of triflones liberating a trifluroromethyl radical suitable for hydrogen atom abstraction (Scheme 24). The regioselectivity of the hydrogen abstraction has been examined and is governed by polar and thermodynamic effects as shown in Scheme 24 [107]. 

An example of allylation is depicted in Scheme 25 (Eq. 25.1). In this reaction, dioxane is used as solvent [104]. The alkenylation reactions (Eqs. 25.2 and 25.3) are run under similar conditions [105]. Very interestingly, these reactions are stereospecific and the geometry of the initial triflone is preserved during the process. Finally, the alkynylation of adamantane is performed in acetonitrile (Eq. 25.4) [110]. The reaction occurs exclusively at the bridgehead position. 

Scheme 25. Fuchs allylation, alkenylation and alkynylation with allyl and vinyl triflones...

Alkenyl and dienyl triflones also insert into unactivated C-H bonds. 

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