- A convenient chemical-microbial method for developing fluorinated pharmaceuticals
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A significant proportion of pharmaceuticals are fluorinated and selecting the site of fluorine incorporation can be an important beneficial part a drug development process. Here we describe initial experiments aimed at the development of a general method of selecting optimum sites on pro-drug molecules for fluorination, so that metabolic stability may be improved. Several model biphenyl derivatives were transformed by the fungus Cunninghamella elegans and the bacterium Streptomyces griseus, both of which contain cytochromes P450 that mimic oxidation processes in vivo, so that the site of oxidation could be determined. Subsequently, fluorinated biphenyl derivatives were synthesised using appropriate Suzuki-Miyaura coupling reactions, positioning the fluorine atom at the pre-determined site of microbial oxidation; the fluorinated biphenyl derivatives were incubated with the microorganisms and the degree of oxidation assessed. Biphenyl-4-carboxylic acid was transformed completely to 4′-hydroxybiphenyl-4-carboxylic acid by C. elegans but, in contrast, the 4′-fluoro-analogue remained untransformed exemplifying the microbial oxidation-chemical fluorination concept. 2′-Fluoro- and 3′-fluoro-biphenyl-4-carboxylic acid were also transformed, but more slowly than the non-fluorinated biphenyl carboxylic acid derivative. Thus, it is possible to design compounds in an iterative fashion with a longer metabolic half-life by identifying the sites that are most easily oxidised by in vitro methods and subsequent fluorination without recourse to extensive animal studies.
- Bright, Tara V.,Dalton, Fay,Elder, Victoria L.,Murphy, Cormac D.,O'Connor, Neil K.,Sandford, Graham
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p. 1135 - 1142
(2013/03/28)
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- Activation of Reducing Agents. Sodium Hydride Containing Complex Reducing Agents. 32. NiCRAL's as Very Efficient Agents in Promoting Cross-Coupling of Aryl Halides
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Nickel-containing complex reducing agents NiCRA-bpy are shown to be the first nickel reagents able to efficiently perform cross-coupling of aryl halides.The presence of KI in the reaction medium generally improves the procedure.The mechanism and influence of the structures of the substrates are discused.
- Lourak, Mouhsine,Vanderesse, Regis,Fort, Yves,Caubere, Paul
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p. 4844 - 4848
(2007/10/02)
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- F-NMR-spectroscopy for the identification of photo products generated from aromatic iodo compounds - IV
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The investigation demonstrates the analytical power of F-NMR spectroscopy for the identification of isomeric substituted fluorobiphenyls.The biphenyls are formed by u.v. irradiation of iodobenzenes in aromatic solvents.A special procedure for the identification is outlined and tendencies of the results-chemical shifts and relative rates for the production of isomers-are discussed in consideration of electronic and steric substituent effects.
- Kelm, J.,Strauss, K.
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p. 689 - 692
(2007/10/02)
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