Perfluorinated cyclic amine

FIGURE 9.10 Perfluorinated lactams prepared by hydrolysis of perfluorinated cyclic amines. 

Due to the combination of lower electronegativity and the presence of unshared electron pair on nitrogen atom, perfluorinated cyclic amines are more reactive toward electrophiles, compared to ethers. As it is demonstrated by Hayashi et al., cyclic perfluorinated amines undergo selective, high-yield conversion into the corresponding lactams 41—45 upon treatment with fuming 112804 ° (Fig- 9.10). 

As it was shown by Sokolov et al., perfluorinated amines are more reactive toward AICI3. The reaction of perfluorinated cyclic amines results in the ring opening and is accompanied by fluorine-chlorine exchange, leading to noncyclic isomeric imidoyl chlorides 80 (Fig. 

The reaction of perfluorinated cyclic amines with strong Lewis acids, such as SbFs or aluminum chlorofluoride (ACF), at elevated temperature results in rapid cleavage of amine, leading to the formation of cyclic perfluorinated imidoyl fluorides (Fig. 9.23). In contrast to AICI3 reactions, this process is catalytic. The outcome of the reaction depends on the structure of amine. For example, the reaction of A-alkyl piperidines or morpholines leads to the elimination of perfluoroalkane... 

Petrov, V.A. Kunanets, V.K. Makarov, K.N. German, L.S. Isomerization of perfluorinated cyclic amines by antimony pentafluoride. Izv. Akad. Nauk SSSR, Ser. Khim. 1989 (3), 646-649. 

ECF of azabicycloalkanes in anhydrous HF forms perfluorinated derivatives, which are also potential components of blood substitutes. Thus perfluoro-A -me-thylazatricyclodecane was obtained in 8.6% yield (69ZAAC62) (Scheme 78). Perfluorinated cyclic amines are formed from 2-azatricyclo-[4.2.2.1 ]undecane... 

Japanese chemists reported on syntheses of perfluorinated cyclic amines by ECF of the hydrocarbon analogs. They synthesized perfluoro-A -alkylperhydroindole, perfluorooctahydroindole, perfluoro-A -methyleneperfluoroquinoline, and perfiuoro-A -cycloalkyl-pyrrolidine (83JPP83-144370, 82M33). 

Electrochemical fluonnation ot N,N dialkylamino-substituted carboxylic acids as their methyl esters produces the analogous perfluorinated tertiary amine carboxylic acid derivatives in 18-30% yields as well as cyclic amine ethers [100]... 

Other examples of electrophilic reactions of perfluorinated heterocyclic compounds include mentioned earlier hydrolysis of cyclic chlorinated ethers 20 (Fig. 9.5), unsaturated ether 27 (Fig. 9.8), and cyclic amines leading to fluorinated lactams (Fig. 9.10). 

Fig. 9.26) by ferrocene or PPh3 was used for the preparation of imidoyl fluorides 81,83, and 91. The cleavage of perfluorinated tertiary amines under the action of SbFs (see Fig. 9.23) is another convenient method for the synthesis of cyclic imines, such as 81-83. 

A wide variety of perfluorinated cyclic materials has been prepared and a large body of experimental material on the synthesis and chemistry of perfluorinated nonaromatic heterocyclic was accumulated. Despite the fact that the saturated perfluorinated heterocycles are expected to be chemically inert, this group of materials actually have an interesting and unusual chemistry, which can be exemplified by reductive defluorination of cyclic perfluorinated N—F amines under the action of mild reducing agents or cleavage of cyclic amines under the action of strong acids. 

A wide range of fluids with similar physical and chemical properties, including linear and cyclic perfluoroalkanes, linear and cyclic perfluoroethers and polyethers, perfluorotertiary amines and, in a few instances, perfluoroalkylhalides, may be considered to be perfluorinated or fluorous . Solvents within these categories are marketed around the world under a series of brandnames (Table 1). In certain instances, the commercial fluids represent mixtures of similar compounds with... 

Redistribution of the electron density in perfluorinated heterocycles leads to the signihcant increase in the basicity of the fluorine substituent, resulting in an unusual reactivity toward strong electrophiles. This effect makes possible reactions, which are virtually unknown for cyclic hydrocarbons, such as reactions of perfluorinated ethers or amines with strong Lewis (AICI3, SbFs, SO3) or protic acids. Short summaries on these reactions can be found in two reviews... 

FIGURE 9.22 Ring opening of cyclic perfluorinated amines under the action of AICI3. 

The mechanism of the reductive defluorination of perfluorinated N F amines may involve a relatively low laying LUMO of N—F bond. The injection of an electron on this orbital leads to the formation of radical anion D, which can further lose fluoride anion, forming radical E. The reduction of E to azaanion F followed by second fluoride anion elimination may lead to the corresponding cyclic imidoyl fluoride as a result of reductive defluorination (Scheme 9.1). 

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