Trifluoromethyl dioxirane

This was also accomplished with BaRu(0)2(OH)3. The same type of conversion, with lower yields (20-30%), has been achieved with the Gif system There are several variations. One consists of pyridine-acetic acid, with H2O2 as oxidizing agent and tris(picolinato)iron(III) as catalyst. Other Gif systems use O2 as oxidizing agent and zinc as a reductant. The selectivity of the Gif systems toward alkyl carbons is CH2 > CH > CH3, which is unusual, and shows that a simple free-radical mechanism (see p. 899) is not involved. ° Another reagent that can oxidize the CH2 of an alkane is methyl(trifluoromethyl)dioxirane, but this produces CH—OH more often than C=0 (see 14-4). ... 

Aryl-l,2,4,5-tetrazines are oxidised by methyl(trifluoromethyl)dioxirane to their previously unknown iV-oxides 96. NMR studies have shown that N-l is oxidised regioselectively <96X2377 >. 

This synthesis is shown in Scheme 13.59. Two enantiomerically pure starting materials were brought together by a Wittig reaction in Step C. The aldol addition in Step D was diastereoselective for the anti configuration, but gave a 1 1 mixture with the 6S, 1R-diastereomer. The stereoisomers were separated after Step E-2. The macrolactonization (Step E-4) was accomplished by a mixed anhydride (see Section 3.4.1). The final epoxidation was done using 3-methyl-3-trifluoromethyl dioxirane. 

CgoO (1) can also be prepared by allowing toluene solutions of CgQ to react with dimethyldioxirane (Scheme 8.3) [28], The so-obtained product is identical to that prepared by photochemical epoxidation [15], Upon treatment of CgQ with dimethyldioxirane, a second product is formed simultaneously (Scheme 8.3), which was identified to be the 1,3-dioxolane 6. Upon heating 6 in toluene for 24 h at 110 °C, no decomposition could be observed by HPLC, implying that 1 and 6 are formed by different pathways. Replacement of dimethyldioxirane with the more reactive methyl(trifluoromethyl)dioxirane allows much milder reaction conditions [29]. At 0 °C and a reaction time of only some minutes this reaction renders a CgQ conversion rate of more than 90% and higher yields for CgoO as well as for the higher oxides. 

FIGURE 13. B3LYP/6-311- -G(3df,2p)-optimized stractures of dioxirane (DO), dimethyldioxirane (DMDO) and methyl(trifluoromethyl)dioxirane (TFDO). Bold numbers for DO are experimental microwave-stractural data. ... 

Part of the mystique surrounding the often assumed high reactivity of dioxiranes stems from the observation that dioxiranes such as methyl(trifluoromethyl)dioxirane (TFDO) are capable of oxidizing saturated hydrocarbons to their alcohols at relatively low temperatures in high yields and with impressive stereoselectivities (equation 8). 

The NMR data of dimethyldioxirane 36 have already been reviewed, but the closely related spectrum of methyl(trifluoromethyl)dioxirane 37 was not reviewed and a comparison of its experimental data with the computed values for the parent dioxirane 38 and of difluorodioxirane 39 can be of interest. Experimental and computed data are gathered in Table 9. 

The synthetically most useful method for the preparation of dioxiranes is the reaction of appropriate ketones (acetone, trill uoroacetone, 2-butanone, cyclohexanone etc.) with Caroate, commercially available as the triple salt of potassium monoperoxysul-fate (KHSOs). The catalytic cycle of the dioxirane formation and oxidation is shown in Scheme 1 in general form. For acetone as the ketone, by simple distillation at a slightly reduced pressure ca 100 torr) at room temperature ca 20 °C), Jeyaraman and Murray successfully isolated dimethyldioxirane (DMD) as a pale yellow solution in acetone (maximally ca 0.1 M). This pivotal achievement in 1985 fomented the subsequent intensive research activity in dioxirane chemistry, mainly the synthetic applications but also the mechanistic and theoretical aspects. The more reactive (up to a thousandfold ) fluorinated dioxirane, methyl(trifluoromethyl)dioxirane (TFD), was later isolated in a similar manner by Curd, Mello and coworkers". For dioxirane derived from less volatile ketones, e.g. cyclohexanone, the salting-out technique has been developed by Murray and coworkers to obtain the corresponding dioxirane solution. 

Methyl(trifluoromethyl)dioxirane (TFD) was isolated by Curd and coworkers . 

Polymer-bound trifluoromethyl aryl ketone 42 was prepared by attaching 4-(trifluoroacetyl)benzoic acid to a suitably functionalized resin and used as a catalyst in Oxone-mediated epoxidations.64 The reactions proceed by in situ generation of the polymer-supported (trifluoromethyl)-dioxirane. A series of epoxides was formed in good to excellent yield. 

Two new reactive, very powerful organic peroxides, dimethyldioxirane and methyl(trifluoromethyl)dioxirane (4), have been introduced.81-83 The latter is more reactive and can be used more conveniently.84 85 Acyclic alkanes give a mixture of isomeric ketones on oxidation with methyl(trifluoromethyl)dioxirane,84,85 while cyclohexanone is the sole product in the oxidation of cyclohexane (99% selectivity at 98% conversion).85 With the exception of norbomane, which undergoes oxidation at the secondary C-2 position, highly selective tertiary hydroxylations can be carried out with regioselectivities in the same order of magnitude as in oxidations by peracids.85-87 A similar mild and selective tertiary hydroxylation by perfluorodialkyloxaziridines was also reported.88 Oxidation with dioxiranes is highly stereoselective 85... 

An efficient oxidizing reagent for oxyfunctionalization of saturated hydrocar bons, methyl(trifluoromethyl)dioxirane, can be prepared from aqueous potassium peroxomonosulfale and 1,1,1-tnfluoropropanone [752] The reaction of this reagent with adamantane gives the corresponding tris(hydroxy)adamantane in high yield [755] (equation 80)... 

Dimethyldioxirane (7) and methyl(trifluoromethyl)dioxirane (8) are the two most effective reagents mainly used in preparative organic chemistry. 

See Bis(trifluoromethyl)dioxirane See Hydrogen Peroxide Acetone See other CYCLIC PEROXIDES... 

Bis(trifluoromethyl)cadmium—1,2-dimethoxyethane adduct, 0584 Bis(trifluoromethyl)chlorophosphine, 0594 Bis(trifluoromethyl)cyanophosphine, 1050 Bis(trifluoromethyl)dioxirane, 1052 Bis(trifluoromethyl) disulfide, 0640a... 

R. Mello, M. Fiorentino, C. Fusco, and R. Curci, Oxidations by methyl (trifluoromethyl)-dioxirane. 2-Oxyfunctionalization of saturated hydrocarbons, J. Am. Chem. Soc., Ill (1989) 6749-6757. 

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