triflates

Triflates refer to compounds containing the triflate group, CF3SO3−, derived from triflic acid (CF3SO3H). The term covers the triflate anion, salts such as sodium triflate (NaOTf), and organic derivatives in which the sulfonate moiety is bound to a carbon atom, giving alkyl triflates (R–OTf) and aryl or vinyl triflates (Ar–OTf, vinyl–OTf).

Triflate esters are excellent leaving groups; once formed, substitution by nucleophiles or cross-coupling can proceed readily. They are typically stable to many reagents but hydrolyze in the presence of water.

Preparation and reagents: The group is introduced from triflic acid or triflic anhydride. Tf2O is widely used to convert alcohols and phenols into alkyl or aryl triflates (R–OTf, Ar–OTf) in the presence of base. Sodium or other metal salts of OTf form stable, non-coordinating counterions.

Uses: Aryl and vinyl triflates are common electrophiles in palladium- or nickel-catalyzed cross-coupling (e.g., Suzuki, Negishi, and Hiyama). Alkyl triflates serve as potent alkylating agents. Triflate groups also function as leaving groups in various substitution reactions and in the activation of hydroxy-bearing substrates.

Safety: Triflate reagents, including Tf2O and triflic acid, are moisture sensitive and highly reactive; they are corrosive and must be handled with appropriate protective equipment and inert atmosphere when necessary.