Cyclohexyl trifluoroacetate

Peroxytnfluoroacetic acid is used tor numerous oxidations of saturated hydrocarbons and aromatic compounds It oxidizes alkanes, alkanols, and carboxylic acids with formation of hydroxylation products [29] Oxidation of cyclohexane with peroxytnfluoroacetic acid proceeds at room temperature and leads to cyclohexyl trifluoroacetate in 75% yield, 1-octanol under similar conditions gives a mixture of isomeric octanediols in 59% yield, and palmitic acid gives a mixture of hydroxypalmitic acids in 70% yield [29]... 

The full reduction of 1,3-dienes with Et3SiH/TFA occurs in certain systems although the yields are only modest.231 For example, 1,3-cyclohexadiene gives a 65% yield of cyclohexyl trifluoroacetate, presumably by way of cyclohexene (Eq. 88).211 On the contrary, 1,4-cyclohexadiene fails to undergo reaction with 10 equivalents of triethylsilane and 20 equivalents of trifluoroacetic acid even after 24 hours at room temperature (Eq. 89). 

The selective oxidation of saturated hydrocarbons is a reaction of high industrial importance. Besides a variety of other oxidants, hydrogen peroxide as a very clean oxidant has also been used for these purposes . As an example, in 1989 Moiseev and coworkers reported on the vanadium(V)-catalyzed oxidation of cyclohexane with hydrogen peroxide (Scheme 146) . When the reaction was carried out in acetic acid cyclohexanol and cyclohexanone were formed, bnt conversions were very poor and did not exceed 13%. Employing CF3COOH as solvent, complete conversions could be obtained within 5 min-ntes. Here, cyclohexyl trifluoroacetate was the main product (85% of the products formed) resulting from the reaction of cyclohexanol (the primary product of the oxidation) with CF3COOH. 

Alkyl cations thus formed may recombine with the nucleophile (Eq. 10) giving tri-fluoroacetates or acetamides under anodic oxidation conditions in CF3COOH or CH3CN, respectively. For example, electrooxidation of cyclohexane (7) in CH2C12/ CF3COOH yielded 84 % cyclohexyl trifluoroacetate (15) [23] oxidation of adamantane (9) gave acetamide (16) cleanly (Scheme 4) [24]. 

The oxidation of cyclohexene under the same conditions afforded a variety of products including cyclohexenyl and cyclohexyl trifluoroacetates, 1,2-cyclo-hexanediol ditrifluoroacetate, and a number of unidentified components. The complex mixture of products is probably formed via rearrangement of various cationic intermediates subsequent to the initial electron transfer process. As a preparative method, the oxidation of alkenes under these conditions also suffers from the competitive addition of trifluoroacetic acid to the olefin ... 

Over the past few years, the debate over the origin of the p-silicon effect on carbocations has narrowed to one of the relative magnitudes of inductive and hyperconjugative factors. Theory and experiment are finally in agreement that hyperconjugation is by far the dominant factor—29 kcal/mol calculated to be from P-stabilization ( ) versus 9 kcal/mol from induction and polarization. The realization of these effects is dramatically revealed in the SnI solvolyses of the conformationally locked cyclohexyl trifluoroacetates (OTFA) (3-5), The relative solvolysis rates at 25 °C for compounds 3-5 are 1, 4 X 10, and 2.4 X 10, respectively. Compound 4 cannot attain the necessary anti-coplanar relationship of the Si-C and C-O bonds, which is present in 5 and required for full hyperconjugative interaction with the cation formed as the C-O bond suffers heterolysis. 

Simple alkanes can be converted to esters with dialkyloxrranes. Cyclic alkanes are oxidized to alcohols with dimethyl dioxirane. " Cyclohexane was converted to cyclohexyl trifluoroacetate with di(trifluoromethyl) dioxrrane and trifluoroacetic anhydride and also with RuCl3/MeC03H/CF3C02H. Dimethyl dioxrrane converts alkanes to alcohols in some cases. Adamantane is converted to adamantyl alcohol with DDQ (p. 1710) and triilic acid. The mechanism of oxygen insertion into alkanes has been examined. ... 

Scheme 3-1 First order rate constants for ionisation, relative to cyclohexyl trifluoroacetate 97% CF3CH2OH...

CIS-1,2-Cyclohexanediol, 257 Cyclohexanone oxime, 2 Cyclohexene, 276 2-Cydohexene-l-ol, 62, 63 CyclohexentHics, 24, 105 Cydohexylnittile, 236 Cyclohexyl trifluoroacetate, 281... 

In another significant study, Lambert et al. reported the following relative rates for a series of conformationally constrained cyclohexyl trifluoroacetates (Lambert, J. B., et al. 

It is expeded that more reactive species will be generated in the presence of a strong add. Indeed, the RuCl3-nH20-catalyzed oxidation of cydohexane in tri-fluoroacetic add and didiloromethane (5 1) with peracetic add gives cyclohexyl trifluoroacetate in 77% (Eq. (7.83)) [136aj. 

---