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Umpolung Reactivity of Difluoroenol Silyl Ethers with Amines and Amino Alcohols. Application to the Synthesis of Enantiopure α-Difluoromethyl Amines and Amino Acids

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journal contribution
posted on 04.04.2008, 00:00 by Florent Huguenot, Anne Billac, Thierry Brigaud, Charles Portella
Difluoroenol silyl ethers, produced in situ from acylsilanes and CF3TMS, react as electrophiles with amines to give difluoroimines, via the corresponding hemiaminal adduct, as evidenced by 19F NMR spectroscopy. Reaction with (R)-phenylglycinol led to 2-difluoromethyloxazolidines. After separation of the diastereomers, reduction with LAH and Strecker-type synthesis gave enantiopure α-difluoromethylamines and α-difluoromethyl-α-amino acids, respectively.