Trifluoroperoxyacetic acid

With aliphatic and alicyclic ketones, it appears that trifluoroperoxyacetic acid is the reagent of choice. It reacts much faster than other... 

More recently, permaleic acid has been recommended as a very satisfactory reagent for the Baeyer-Villiger reaction. It reacts almost as fast as trifluoroperoxyacetic acid and does not require buffering. Unfortunately, neither of these two reagents has been used extensively on 20-keto steroids a patent claims the conversion of progesterone to testosterone acetate with trifluoroperoxyacetic acid, but a later communication describes the ready reaction of 3-keto-A" -steroids with this reagent. 

Consistent with this mechanism is the observation that trifluoroperoxyacetic acid is reported to be the most effective peracid in aromatic oxidation134 the great stability of the trifluoroacetate anion causes it to be an excellent leaving group so that heterolysis to give hydroxyl cations OH+ occurs most readily. 

The rate of epoxidation of alkenes is increased by alkyl groups and other ERG substituents and the reactivity of the peroxy acids is increased by EWG substituents.72 These structure-reactivity relationships demonstrate that the peroxyacid acts as an electrophile in the reaction. Decreased reactivity is exhibited by double bonds that are conjugated with strongly electron-attracting substituents, and more reactive peroxyacids, such as trifluoroperoxyacetic acid, are required for oxidation of such compounds.73 Electron-poor alkenes can also be epoxidized by alkaline solutions of... 

Also other examples.518,703 Using Trifluoroperoxyacetic Acid... 

Deprotonation of S7NF1 produces the thermally unstable, yellow [S7N] anion, which decomposes to the deep blue [S4N] anion.69 The oxidation of S7NH with trifluoroperoxyacetic acid yields S7NH(0), while oxidation with SbCl5 in liquid sulfur dioxide generates the [NS2]+ cation. 

The detellurative methoxylation of the telluroxides also proceeds in high yields by treatment with trifluoroperoxyacetic acid (generated in situ from TFA and (method C). 

Benzyl ( )-ra-2-Acetoxycyclobutanecarboxylate Typical Procedure using Trifluoroperoxyacetic Acid 37... 

Baeyer-VUliger oxidation by trifluoroperoxyacetic acid converts a chlo-rofluoroalkyl ketone into an ester L71] (equation 63)... 

Ring Oxidation (with trifluoroperoxyacetic acid, F3CC—OOH)... 

Peracid epoxidations are often favorable due to higher chemoselectivity the diastereoselectivity under standard conditions (e.g., 3-chloroperoxybenzoic acid in dichloromethane, see Section 4.5.1.1.1.) is mostly satisfactory for compounds with equatorial hydroxy groups (95 5 cis-epoxide with 2-cyclohexcnol50), when purification does not give problems. Diastereoselectivity in pcracid epoxidation of compounds with axial hydroxy groups is somewhat lower (90 10 cw-epox-ide with fra s-5-te/Y-butyl-2-cyclohexenol. Trifluoroperoxyacetic acid is reported to be much more diastereoselective (100 1 in both cases, see Houben-Weyl, Vol. E13/2, pp 1263, 1264). 

Conjugation of the alkene double bond with an electron-withdrawing group reduces the rate of epoxidation. Thus, a, 3-unsaturated carboxylic acids and esters require a stronger oxidant, such as trifluoroperoxyacetic acid, for oxidation. 

One of the first examples of Baeyer-Villiger reactions to be reported involved the oxidation of menthone using Caro s acid. The Baeyer-Villiger oxidation of cycloalkanones (Eq. 26) using trifluoroperoxyacetic acid generated by the inter-... 

---