Trifluoromethyl-containing

Various trifluoromethyl containing a, -unsaturated acids, esters, ketones, and nitriles have been used as dienophiles Details regarding regiochermstry and stereochemistry have been reported [2S, 98, 99] (equations 82-84)... 

Trifluoromethyl-containing valence bond isomers have been reviewed (81ACR76). 

Khunt RC, Akbari JD, Manvar AT, Tala SD, Dhaduk MF, Joshi HS, Shah A (2008) Green chemistry approach to synthesis of some new trifluoromethyl containing tetrahydropyrimi-dines under solvent-free conditions. Arkivoc 277-U8... 

Shen L, Zhang J, Cao S, Yu JL, Liu NJ, Wu JJ, Qian XH (2008) One-pot synthesis of trifluoromethyl-containing pyrazoles via sequential Yb(PFO)(3)-catalyzed three-component reaction and IBX-mediated oxidation. Synlett 3058-3062... 

The main commercially available and/or easily accessible chemicals for the synthesis of trifluoromethyl-containing molecules are discussed in this section. 

A range of trifluoromethyl-containing pyrazolo[3,4- ]pyridines have been prepared, in good yield, from the reaction of 4,4,4-trifluoro-3-oxobutanoates with electron-rich amino pyrazoles (Equation 53 Table 29) <2003S1531>. 

Recently two other trifluoromethyl-containing monomers have been introduced—OBABTF and DABTF—that have been shown to decrease the dielectric constant and moisture absorption.Polyimides made from OBABTF had a lower dielectric constant than materials made from the unfluorinated analogue ODA in every case with PMDA, BPDA, and ODPA. 

The development of new types of reagents for the formation of perfluoroalkyl derivatives of metals is of interest since, as discussed below (Section II), the types of trifluoromethyl complexes which could be prepared until quite recently have been severely limited by the synthetic methods that have been historically available. Virtually all of the trifluoromethyl-containing transition metal species prepared prior to the 1980s arose from only two types of reactions thermal decarbonylations of trifluoroacetyl complexes or oxidative additions of CF3I. 

Each of these synthetic methods is limited to low valent metal complexes in each case at most two CF3 groups have been substituted onto a metal ion. In Section III some of the contemporary approaches that have been designed to curtail the enforced reliance upon only two precursors are indicated and some of the early results from these preliminary studies into the chemistry of trifluoromethyl-containing transition metal compounds are presented. 

Immediately upon their isolation, trifluoromethyl-containing derivatives of (low valent) transition metals were universally found to be much more robust, both thermally and oxidatively, than their methylated counterparts. Many perfluoromethyl complexes, for example, have been found to be unreactive in air whereas the corresponding methyl derivatives are air sensitive. Under anaerobic conditions a number of trifluoromethylated species decompose at temperatures approximately 100°C higher than the analogous methylated compounds. 

Once the trifluoromethyl-containing organometallic compounds have been formed, ligand-exchange reactions usually proceed readily. The first example was reported by Hieber, who observed that NO reacted cleanly with CF3Co(CO)3P(0)3 to afford CF3Co(NO)2P(Ot/>)3 quantitatively (22). 

Fig. 11. Trifluoromethyl-containing generation of sterol biosynthesis inhibitors.

Chlorfenapyr (Phantom ), a trifluoromethyl-containing pyrrole ring insecticide, belongs to a new class of uncouplers of oxidative phosphorylation [80], The original insecticidal lead that resulted in chlorfenapyr was the fermentation product dioxapyrrolomycin, isolated from a Streptomyces strain [81], The presence of the trifluoromethyl group is essential for a broad spectrum of insecticide and acaricide activity. 

Benzoylphenyl urea. Substitution at the anilide portion of the molecule, particularly at the 4 position, has resulted in a variety of different commercial benzoylphenyl urea insecticides diflubenzuron (Dimilin ), with chlorine at the 4 position of the anilide, provides one of the earliest examples [153], The trifluoromethyl-containing benzoylphenyl ureas flufenoxuron and bistrifluron were discussed in Section 2.1.1.2, and chlorfluazuron was discussed in Section 2.1.2.2. Tefluben-zuron (Nemolt ) is used for the control of lepidoptera, coleoptera, diptera, and hemiptera larvae on vines, pome fruit, cabbages, vegetables, and cotton. 

As well as atmospheric sources, pyrolysis of fluorine-containing polymers, which may occur in engine oil additives, non-stick cookware or incinerated medical equipment (i.e. syringes) and household waste, may also produce TFA. This process may also produce perfluorinated alkanes and cycloalkanes, which have significant GWP, and have estimated tropospheric half-lives of more than 2000 years. Trifluoroacetate may also be produced by metabolism of trifluoromethyl-containing drugs such as Prozac, and anaesthetics including halothane and iso-fluorane [4],... 

Aoki and Koga also reported a structurally simpler trifluoromethyl-containing and readily accessible chiral base. Deprotonation of 28 with 40 did not require HMPA to yield the silylenol ether (R)-29 in high ee (92%) (Scheme 26)62. 

Reactions of 2-trifluoromethylchromones with ethyl mercaptoacetate have been carried out to give trifluoromethyl containing l,2-dihydrothieno[2,3-c]chromen-4-ones 25-28. Two thieno[2,3-c]coumarins have been prepared from the corresponding sulfoxides using the Pummerer rearrangement followed by aromatization <03T2625>. 

Trifluoromethyl-containing Amino Acids in Protein Design... 

Soloshonok, V. A., Kukhar, V., Pustovit, Y. and Nazaretian, V. (1992) A new and convenient synthesis of S-trifluoromethyl-containing amino acids. SynLett., 657-658. 

The purpose of the present review is to examine the current status of the chemistry of trifluoromethyl-containing transition metal compounds where the term transition metal had been defined to include the metals of groups 3-12. The early studies in this area have been discussed previously several times (1-4), and there has been no effort to provide a comprehensive literature coverage of the CF3-metal chemistry that was reported prior to 1980. 

The first trifluoromethyl-containing derivative of a d block element was formed when Mn(CO)s(COCF3) was thermally decarbonylated to give Mn(CO)5(CF3) (10) ... 

For many years now, the reactivity of trifluoromethyl bromide has been underestimated. During the past decade the major breakthrough in this area has been the realisation that trifluoromethylation of organic compounds with this halide can be induced by mild reductants such as thiolates, zinc or sulfoxylate radical anion. Nowadays, a great variety of fluorinated products are available by these new methods sodium triflinate and triflic acid, trifluoromethylated alcohols, trifluoromethyl-containing aromatic compounds, ethyl trifluoropyruvate, trifluoromethylsulfides. ... 

The Perkin reaction has been used to synthesize trifluoromethyl-containing building blocks that are very useful in the pharmaceutical and agrochemical industries. For example, 2,2,2-trifluoro-l-(4-methylphenyl)ethanone (43) reacts with acetic anhydride, when heated in the presence of sodium acetate, to produce 3-polyfluoroalkyl- -cinnamic acid 44.11... 

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