- Heteroaryl-N-difluoromethyltrimethylsilanes - Versatile sources of heteroaryl-N-difluoromethyl anions in reactions with carbonyl compounds
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An efficient procedure for synthesizing heteroaryl-N-difluoromethyltrimethylsilanes - new nucleophilic difluoromethylene synthons - from easily available N-bromodifluoromethylated heterocycles, chlorotrimethylsilane and aluminium powder in triglyme or N-methylpyrrolidinone on a preparative scale in 71-75% isolated yield is described. Heteroaryl-N-difluoromethyltrimethylsilanes and benzaldehyde react under fluoride ion catalysis to give 1-(1,1-difluor-2-hydroxy-2-phenyl-ethyl)heteroaryls, whereas for anionic heteroaryl-N-difluoromethylation of cyclohexanone a stoichiometrical mixture of heteroaryl-N-difluoromethyltrimethylsilanes and tetramethylammonium fluoride has to be used.
- Bissky,Staninets,Kolomeitsev,R?schenthaler
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p. 374 - 378
(2007/10/03)
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- Generation of heteroarylium-N-difluoromethylides and heteroaryl-N-difluoromethyl anions and their reactions with electrophiles: Heteroaryl- and heteroarylium-N-difluoromethyl trimethylsilanes and a new heteroaryl-N-trifluoromethane
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Reductive debromination of N-bromodifluoromethyl-4-dimethylaminopyridinium bromide, 1-bromodifluoromethyl-imidazole, 1-methyl-3-bromodifluoromethyl-imidazolium bromide and 1-bromodifluoromethyl-2-methyl-benzimidazole using tetrakis(dimethylamino)ethylene (TDAE) or tris(diethylamido)phosphite leads to new fluorinated carbanionic species, namely heteroarylium-N-difluoromethylides and heteroaryl-N-difluoromethyl anions. In the presence of electrophiles such as benzaldehyde, chlorodiphenylphosphine and chlorotrimethylsilane, the corresponding heteroarylium- and heteroaryl-N-difluoromethylated derivatives, imidazole-N-difluoromethyl-phosphines and -silanes, 2-methyl-benzimidazole-N-difluoromethyltrimethyl-carbinols-phosphines and -silanes were obtained. Similar 4-dimethylaminopyridinium derivatives were synthesized.
- Bissky, German,Roeschenthaler, Gerd-Volker,Lork, Enno,Barten, Jan,Medebielle, Maurice,Staninets, Vasilij,Kolomeitsev, Alexander A.
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p. 173 - 181
(2007/10/03)
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