Synthesis and structure of nitrones derived from 2-trifluoromethyl bornane 3-imines |
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Authors: | Grzegorz Mloston Emilia Obijalska Anthony Linden |
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Affiliation: | a Department of Organic and Applied Chemistry, University of Lodz, Tamka 12, PL-91-403 Lodz, Poland b Organisch-chemisches Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland |
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Abstract: | Upon treatment with (trifluoromethyl)trimethylsilane (CF3SiMe3), 3-(N-alkyl or 3-N-aryl)imines of camphorquinone of type 1 smoothly undergo stereoselective conversion to yield 2-endo-trifluoromethylated 1:1 adducts 2, which, after subsequent desilylation with sodium borohydride in boiling alcoholic solutions, were converted into imino alcohols 3. Unexpectedly, oxidation of 3 with m-CPBA resulted in the formation of a new type of trifluoromethylated nitrones 5 (and not the expected oxaziridines) in a stereoselective manner. In the case of 5a, the (Z)-configuration of the CN double bond of the nitrone unit was unambiguously established by an X-ray crystal-structure determination. However, photolysis of 5a led to the exo,exo/exo,endo mixture of the isomeric oxaziridine 7; the two stereoisomers were separated chromatographically. |
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Keywords: | Imines Nitrones Oxaziridines Oxidations Trifluoromethylbornan-2-ols |
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