Fluorine organic compounds Asymmetric fluorination

In contrast, there are now many examples in the literature to indicate that, when presented with organic compounds already labelled with fluorine, enzymes may be tolerant to the presence of fluorine, depending on the number of C-F bonds and their location [89, 90]. For example, baker s yeast may lead to significant asymmetric reduction of carbonyl (Figure 1.7). 

Reviews (a) F. A. Davis, H. Qi, G. Sundarababu, Asymmetric Fluorination in Enantiocontrolled Synthesis of Fluoro-Organic Compounds Stereochallenges and Biomedical Targets (V A. Solosho-nok Ed.), John Wiley and Sons, New York, 1999 (b) G. Resnati, Tetrahedron 1993, 49, 9385. 

P. V. Ramachandran, H. C. Brown, Asymmetric reduction of fluorine-containing carbonyl compounds, in V. A. Soloshonok (Ed.) Enantiocontrolled Synthesis of Fluoro-Organic Compounds Stereochemical Challenges and Biomedical Targets, John Wiley Sons, Inc., Hoboken, 1999, pp. 179-228. 

Enantioselectively introducing fluorine atom into small organic compounds is of great importance for life sciences and high-performance materials. To this end, a fluorous cinchona alkaloid ester 29 was developed as an organocatalyst for the asymmetric fluorination of p-ketoesters (Scheme 7.34) [50]. The fluorous catalyst... 

The importance of fluorinated organic componnds both in medicinal chemistry and biochemistry has resulted in much recent attention towards efficient carbon fluorine bond formation [30]. The reactions developed include a very successful electrophilic asymmetric mono-fluormation of 1,3-dicarbonyl compounds [31]. A nucleophilic variant was also investigated. In this context, the groups of Togni and Mezzetti have established that ruthenium Lewis acids could efficiently catalyze fluorination reactions [32]. In the presence of [Ru(l,2-bis(diphenylphosphino)ethane)2Cl][PF6] (8) (10 mol%), fert-butyl iodide reacted at room temperature with TIF (1.1 equiv.) to yield fert-butyl fluoride (84% yield). This reaction was extended successfully to a range of organic halides (Entries 1-3, Scheme 10.19). The use of the chiral complex [Ru((lS,2S)-N,N bis[2-diphenylphos-phino)benzylidene]diaminocydohexane))Cl][PF6] (9) showed modest chiral induction at the outset of the reaction (Entry 4, Scheme 10.17). The near-racemic mixture obtained at completion points to an SNl-type process in this nucleophilic halide... 

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