Perfluoroalkyl group, activation

The perfluoroalkyl groups activate fluoro or nitro displacement by phenoxides that is quite similar to... 

A perfluoroalkyl group activates fluorine atom in 2-fluoro-3-trifluoromethylfurans to nucleophilic substitution with a broad range of nucleophiles [102-105]. Huorine can be efficiently substituted by alkoxy or phenoxy groups, aliphatic or heterocyclic thiols and amines or reduced with lithium aluminium hydride. The C-nucleophiles like cyanide or malonate anion as well as phenylithium and phenylmagnesium bromide can also be involved into the reaction. 

Under sonication conditions, the reaction of perfluoroalkyl bromides or iodides with zinc can be used to effect a variety of functionalization reactions [39, 40, 41, 42] (equation 30) Interestingly, the ultrasound promoted asymmetric induction with the perfluoroalkyl group on the asymmetric carbon was achieved by the reaction of perfluoroalkyl halides with optically active enamines in the presence of zinc powder and a catalytic amount of dichlorobisftc-cyclopenta-dienyl)titanium [42] (equation 31)... 

Fluorocarbons with a hydrophilic functional group are very active surfactants [23]. Less than 1% of ionic or nonionic surfactants with perfluoroalkyl groups can reduce the surface tension of water from 72 to 15-20 dyne/cm, compared with 25-35dyne/cm for typical hydrocarbon surfactants [24] Perfluoroether surfactants are about as active as their perfluoroalkyl counterparts of similar chain length [25, 26], but fluorosurfactants with more polar alkyl end groups are considerably less active than their perfluoroalkyl analogues (Table 7)... 

Recent investigations focus on the introduction of fluorine atoms and perfluoroalkyl groups into molecules of known bioactive compounds to improve their properties. The modification of biological activity in this way can be connected with the following factors ... 

These examples demonstrate the efficiency of the activated double bonds with functional groups for the syntheses of various heterocyclic compounds with perfluoroalkyl groups when binucleophilic regents are... 

Thus conditions are provided for further interactions between active perfluoroazaalkene and the reaction product whose structure involves an N-C-NH triad. This opens up an opportunity to construct bicyclic nitrogen-containing heterocycles with perfluoroalkyl groups. 

The optically active carbinols 6 (77 85% ee) of the compounds listed in the table above are only obtained in small amounts (3-9% yield). However, the situation changes if the perfluoroalkyl group is an immediate substituent at the carbon-carbon double bond. In this case the keto group is preferably reduced affording the corresponding unsaturated optically active alcohol 7 which is further converted into the saturated optically active alcohol 8 after prolonged incubation 52. Since the carbon-carbon double bond bears, in this case, a substituent other than H, a second center of asymmetry is created during the double-bond reduction. The ratios for the two observed diastereomers (d.r. see table) are a measure of the enantiospecificity of the enzymatic reductions. 

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