Trifluoromethanesulfonates alkenyl

The last comprehensive review on electrophilic reactions of fluoroolefins was published in 1969 [6], Since then, several reviews and papers dealing with different aspects of this chemistry, such as alkylation and alkenylation reactions [7], addition of halogen fluorosulfates [8], trifluoromethanesulfonates [9] and halogen fluorides [10] to fluoroolefins have been published. Additional information on the reactions involving carbocations could be found in two recent review articles [11,12] some data on the subject are scattered in several books and journals [13-19]. 

Takai, K., Tagashira, M., Kuroda, T., Oshima, K., Utimoto, K., Nozaki, H. Reactions of alkenylchromium reagents prepared from alkenyl trifluoromethanesulfonates (triflates) with chromium(ll) chloride under nickel catalysis. J. Am. Chem. Soc. 1986, 108, 6048-6050. 

Metal-catalyzed hydroarylation of alkynes catalyzed by electrophilic transition metal complexes has received much attention as a valuable synthetic alternative to the Heck and cross-coupling processes for the synthesis of alkenyl arenes (384). Metal trifluoromethanesulfonates (metal triflates) [M(OTQn M = Sc, Zr, In] catalyze the hydroarylation of alkynes via 71 complexation to give 1,1-diarylalkenes in very good yields (Scheme 32) (385). The reaction likely proceeds by a Friedel-Crafts mechanism via the alkenyl cation intermediate where the aryl starting material also serves as the solvent. 

MeOTf has been reported to effect the dealkoxylation of a perfluoroalkyltrialkoxyboronate to generate the corresponding boronic ester, l Conversely, an alkenyl boroxycarbene complex was reacted with MeOTf to remove the borane-based chiral auxiliary yielding a Fischer carbene complex. l l ferf-Amide substituted oxetanes rearranged in anhydrous nitrobenzene at 150 °C with a catalytic amount of MeOTf to produce ester-substituted azetidines (eq 16).i Other acids such as boron trifluoride ether-ate, trifluoromethanesulfonic acid, and benzylthiolanium hexaflu-oroantimonate led to low yields of the desired azetidines. 

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