Knochel fluorination

Scheme 15.61 Knochel fluorination of aryl Grignard reagents.

FI.FI. Coenen, B. Klatte, A. Knochel, M. Schuller, G. Stocklin, Preparation of n.c.a. [i7-i8F]f uoroheptadecanoic acid in high yields via aminopolyether supported, nucleophilic fluorination, J. Label. Compds Radiopharm. 23 (1986) 455-467. 

For a report on selenium-catalyzed epoxidations with hydrogen peroxide in perfluroalkanes (not fluorinated alcohols), see Betzemeier, B., Lhermitte, F., and Knochel, P. (1999) Synlett, 489-491. 

Yamada S, Gavryushin A, Knochel P (2010) Convenient electrophilic fluorination of functionalized aryl and heteroaryl magnesium reagents. Angew Chem Int Ed 49 2215-2218... 

The design of a novel series of cycUn-dependent kinase (CDK) inhibitors with a macrocyclic quinoxaline-2-one 208 is reported (Kawanishi et al. 2006), where 208 was synthesized as shown in Scheme 5.50. The deprotonation of the fluorine-adjacent position of l-fluoro-2-iodobenzene 209, with LDA, followed by the carbon dioxide trapping and then esterification of the carboxylic acid, led to methyl 2-fluoro-3-iodobenzoate. The iodomagnesium exchange of methyl 2-fluoro-3-iodobenzoate according to Knochel s procedure (Knochel et al. 2003) followed by chloroglyoxylic acid ethyl ester resulted in ketoester 210, which was coupled with 3-[(tert-bulyldimethylsilyl)oxy]benzene-1,2-diamine to... 

The preparation of aryl fluorides through the treatment of aryl Grignard reagents with a source of F has been reported by Knochel and Beller (Schemes 7.46 and 7.47) [79-81]. Knochel generated aryl Grignards at low temperature and treated them with NFSI. The choice of solvent was altical to the success of the fluorination step, and the authors found that CHjClj/perfluorodecaUn mixtures (4 1) afforded higher yields of the aryl fluorides. 

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