Bismuth trifluoromethanesulfonate

Ollevier T, Nadeau E, Desyroy V (2009) Bismuth(III) trifluoromethanesulfonate. In eE-EROS Encyclopedia of reagents for organic synthesis 41. Wiley, New York... 

Finally, it s worth emphasizing that trivalent bismuth salts such as the chloride, nitrate, and trifluoromethanesulfonate (triflate) are extremely attractive as Lewis acid catalysts. Applications include Friedel-Crafts acylations, Diels-Alder reactions, esterifications. 

Bismuth(III) trifluoromethanesulfonate D3i(OTf)3] has been established as an efficient catalyst (0.05 molar equiv.) for the sulfonylation of a range of substituted benzenes by sulfonyl chlorides and sulfonic anhydrides. With the former, ligand exchange is believed to lead to the formation of a mixed sulfonic anhydride (RS020Tf) which is the reactive sulfonylating species. 

Bismuth tris-trifluoromethanesulfonate has been found to be an efficient catalyst for the Mukaiyama aldol-type reactions (Equation (8.14)). The catalytic activity of this catalyst is higher than the one reported for the rare earth triflates M(OTf)3 (M = Sc, Ln). In its presence the mechanism involves a transmetallation step [33]. The catalyst s water stability allows the recovery and recycling. 

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