Trifluoroethyl groups

The trifluoroethyl group was used as an activating group in the phosphotriester approach to oligonucleotide synthesis, as well as a protective group that could be removed with 4-nitrobenzaldoxime (tetramethylguanidine, dioxane, H20). ... 

Characteristic proton and carbon data for compounds containing the trifluoroethyl group are given in Scheme 5.21. 

For example, the 1,2,2 trifluoroethyl group has found use in the fungicide tetraconezole (6-1), whereas the 1,1,2,2-tetrafluoroethyl group is encountered in the benzoylphenylurea insecticide hexaflumuron (6-2), which is used to control locust and grasshoppers in Sahalian grasslands (Fig. 6.1). 

The common 2,2,2-trifluorocthyl group was discussed in Chapter 5. Less commonly encountered is the 1,1,2-trifluoroethyl group, the ether... 

Halazepam Halazepam, 7-chloro-1 -(2, 2, 2 -trifluoro-1 -ethy 1)-l,3-dihydro-5-pheny 1-2//-l,4-benzodiazepin-2-one (5.1.19), also differs from diazepam in that it has a substituent on the nitrogen atom in the first position of the benzodiazepine system, which in this case is represented by the 2, 2, 2 -trifluoroethyl group. It can be made by any of the diagrams described above [13,14],... 

Characteristic proton and carbon data for compounds containing the trifluoroethyl group are given in Scheme 5.23. The series of 2-, 3-, and 4-butanamines provides insight regarding trends in proton chemical shifts. 

An example of CF3 bound to boron in a boronic ester is provided in Scheme 5.27, as is an example of a boronic ester with the CF3 group one carbon away. The fluorines of this trifluoroethyl group are perhaps the most deshielded of any CF3 group bound to a saturated carbon. 

The difference in aggregation between these structurally similar amides, dimers versus trimers in toluene and monomers versus dimers in THF, is surprising. It is likely due to the different steric requirements of the substituents on the nitrogen, the smaller methyl group in Davidsson s study compared to the larger neopentyl or 2,2,2-trifluoroethyl group in Koga s study. 

Note The trifluoroethyl groups alter reaction stereoselectivity. 

Introduction of a trifluoroethyl group at the a-carbon of the nitro group of 280 by a sequence of reactions - (l,5-diazabicyclo[4.3.0]non-5-ene) (DBU)-catalyzed alkylation with trifluoroacetaldehyde hemiacetal in MeCN, dehydration with acetic anhydride-pyridine, and reduction of the C-C double bond with NaBH4 - produces 281. 6-Trifluoroethyl-L-lysine 282 can be prepared from 281 (see Scheme 9.60) [88]. 

The value of K has been measured for several amines with 2-methylpropanal. The effect of the structure of the alkyl group is quite small, although the trifluoroethyl group significantly reduces imine stability. 

I have been told of an analogue of MDE that has been synthesized, and explored by the researcher who synthesized it. It contains the N-trifluoroethyl group common to several pharmaceuticals such as Quazepam. The analogue is... 

Onomura O, Ishida Y, Maki T, Minato D, Demizu Y, Matsumura Y (2006) Electrochemical oxidation of L-Prolinol derivative protected with l-Alkoxy-2,2,2-trifluoroethyl group. Electrochemistry 74 645-648... 

In this contribution, we will only consider polymers with longer i/segments (alkyl and perfluoroalkyl units directly linked via C—C— bond, not by functional groups like ester, amide, and urethane as, for instance, in References 39 and 40). Only /segments able to self-organize will be discussed. We will comment only briefly on polymers with short i/groups such as trifluoroethyl groups. Reviews about this polymer type... 

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