Methyl, trifluoro-, oxide

Recently, Mello et al. have disclosed a simple and robust protocol for the generation of methyl(trifluoromethyl)-dioxirane from an aqueous solution of 1,1,1-trifluoroacetone hydrate, sodium bicarbonate, and peroxomonosulfate on a preparative scale (typically <2 g the authors suggest multiple iterations for larger scales). The methyl(trifluoro-methyl)dioxirane is removed from the reaction mixture by the evolved gases (O2, CO2) and has been applied to the oxidation of substrates in a second reaction zone (e.g., the epoxidation of cyclohexenone Scheme 33) <2007S47>. 

Only a few new reports of ring oxidations have appeared. One method uses dimethyldioxirane or methyl(trifluoro-methyl)dioxirane to convert 2,2-dimethyl-l,3-dioxolanes into 2-hydroxyketones under mild conditions (Equation 29) <1996TL115>. Ozonolysis of 1,3-dioxolanes has also been examined, and the primary reaction product of 2-alkyl-1,3-dioxolanes with ozone was identified as the 2-alkyl-l,3-dioxolan-2-ol <2002JA11260, 2004JA16093>. 

The N(l) atom of 3-aryl-l,2,4,5-tetrazines is oxidized regioselectively by methyl(trifluoro-methyl)dioxirane to give the hitherto unknown iV(l)-oxides (96T2377). 

Bis(trimethylsilyl) oxide reacts with phosphoryl fluoride or pyrophosphoryl fluoride to give derivatives with P-O-Si linkages (9.272) and (9.273). With tris (trifluoro-methyl)phosphine oxide a trigonal bipyramidal phosphorane is obtained (9.274). 

Ketones and Other Oxygen Functions. Various ketones can be converted to the corresponding dioxiranes by treatment with buffered aqueous solutions of Oxone (eq 1). Of particular interest are dimethyldioxirane (R = R = Me) and methyl(trifluoro-methyl)dioxirane (R = Me, R = CF3) derived from acetone and l,l,l-trifluoro-2-propanone, respectively. The discovery of a method for the isolation of dilute solutions of these volatile dioxiranes in the parent ketone by codistillation from the reaction mixture has opened an exciting new area of oxidation chemistry. Solutions of dioxiranes derived from higher molecular weight ketones have also been prepared. ... 

Polymer-bound phenyliodine difluoride, which also has been used as a reagent to add fluorine to alkenes, can be prepared by the addition of xenon difluoride to the polymer [134, 135 136] Methyl iodide is converted to trifluoro methyliodine difluoride by treatment with fluorine at -110 C [137] Perfluoro-alkyliodine tetrafluorides could be synthesized from the perfluoroalkyliodine difluorides and fluorine [138] or chlorine trifluoride [139] Perfluoroalkyl [140] and perfluoroaryl [141] iodides are oxidized to the corresponding iodine difluorides by chlorine trifluoride. 

On reaction of methyl trifluoropyruvate with phosphorus pentachlonde 1,1,2,2 tetrachloro-3,3,3-trifluoro-l-methoxypropane IS obtained [273] Hexafluo-roacetone hydrazone is oxidized to bis(tnfluoromethyl)diazomethane upon tieat-ment with phosphorus pentachlonde [274]... 

Notable examples of general synthetic procedures in Volume 47 include the synthesis of aromatic aldehydes (from dichloro-methyl methyl ether), aliphatic aldehydes (from alkyl halides and trimethylamine oxide and by oxidation of alcohols using dimethyl sulfoxide, dicyclohexylcarbodiimide, and pyridinum trifluoro-acetate the latter method is particularly useful since the conditions are so mild), carbethoxycycloalkanones (from sodium hydride, diethyl carbonate, and the cycloalkanone), m-dialkylbenzenes (from the />-isomer by isomerization with hydrogen fluoride and boron trifluoride), and the deamination of amines (by conversion to the nitrosoamide and thermolysis to the ester). Other general methods are represented by the synthesis of 1 J-difluoroolefins (from sodium chlorodifluoroacetate, triphenyl phosphine, and an aldehyde or ketone), the nitration of aromatic rings (with ni-tronium tetrafluoroborate), the reductive methylation of aromatic nitro compounds (with formaldehyde and hydrogen), the synthesis of dialkyl ketones (from carboxylic acids and iron powder), and the preparation of 1-substituted cyclopropanols (from the condensation of a 1,3-dichloro-2-propanol derivative and ethyl-... 

Trifluoroacetonitrile oxide has been used in the synthesis of trifluoro-methyl isoxazoles and isoxazolines (84BCJ2184 86BCJ2631). In the presence of a base it dimerizes to a dioxadiazine (84JOC919). 

Tagat, J.R., Steensma, R.W., McCombie, S.W. et al. (2001) Piperazine-based CCR5 antagonists as HIV-1 inhibitors. II. Discovery of 1 - [(2,4-dimethyl-3-pyridinyl)carbonyl]-4- methyl-4- [3 (S)-methyl-4- [ 1 (5)- [4-(trifluoro- methyl)phenyl]ethyl]-l-piperazinyl]-piperidine Nl-oxide (sch-350634), an orally bioavailable, potent CCR5 antagonist. Journal of Medicinal Chemistry, 44 (21), 3343-3346. 

Other useful dehydrating agents are dimethylaminosulfur trifluoride (DAST), methyl A -(triethylammoniosulfonyl)carbamate (Burgess salt), acetic anhydride, oxalyl chloride, and phosphorous oxychloride, each one in combination with triethylamine (89). Dehydration of O-sUylated hydroxamic acids using trifluoro-methanesulfonic anhydride and triethylamine under mild conditions also gave nitrile oxides, which in the presence of olefins led to the formation of 2-isoxazolines in moderate to good yields (90). In view of the less readily available starting materials, this method probably will be of limited use. 

Recently, Olah and co-workers reported a new route to tributyl(trifluoro-methyl)tin via in situ formation and capture of the trifluoromethyl anion by trialkyltin oxide [106]. Reaction of trimethyl(trifluoromethyl)silane with tribu-tyltin oxide in the presence of catalytic TBAF in THF afforded the corresponding tributyl(trifluoromethyl)tin in good yield (Scheme 38). This reaction system was first reported by Warner and Buchwald [107]. 

Iron(ll) sulfate. CopperO) trifluoro-methylsulfonatc. Cyanuric chloride. Di-n-butyltin oxide. N-Methyl-N-phcnylaminocthynyllithium. Oxygen, singlet. 

Bobbitt, J. M., Periodate Oxidation of Carbohydrates, 11, 1-41 Boeseken, J., The Use of Boric Add for the Determination of the Configuration of Carbohydrates, 4, 189-210 Bonner, T. G., Applications of Trifluoro-acetic Anhydride in Carbohydrate Chemistry, 16, 59-84 Bonneb, William A., Friedel-Crafts and Grignard Processes in the Carbohydrate Series, 6, 251-289 Bourne, E. J., and Peat, Stanley, The Methyl Ethers of D-Glucose, 6, 145-190... 

A special oxidizing agent. A.A-dichlorotrifluorornethanesulfonamide, converts aryl trifluoro-methyl sulfides into sulfimides at room temperatures (Table 19).296 Bis(perfluorophenyl) sulfide is converted into the sulfone 12 by refluxing for an extended period with in situ prepared peracetic acid.297... 

Telramethyl-2-(trifluoro-l-trifluoio-methyl-l-lrimethi lsilyloxy-ethyl)- -2-oxide ElOb,. 683 (Fc —acetone + R4-2-OS1R3 - l,3.2-dioxaphospho-lane)... 

MPO 3-methyl, pyridine-N-oxide HTTMA thenoyl trifluoro (methyl)... 

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