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3‐Tocopherylisoxazolines by [2+3] Cycloaddition
Author(s) -
Rosenau Thomas,
Adelwöhrer Christian,
Hofinger Andreas,
Mereiter Kurt,
Kosma Paul
Publication year - 2004
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200300636
Subject(s) - chemistry , cycloaddition , nitrile , triethylamine , nitration , oxide , organic chemistry , catalysis , medicinal chemistry
New isoxazoline derivatives of α‐tocopherol ( 1 ), the main component of vitamin E, were synthesized in a facile, two‐step sequence consisting of nitration followed by 1,3‐dipolar cycloaddition. 5‐Nitromethyl‐γ‐tocopheryl acetate ( 3 ), obtained from the cheap α‐tocopheryl acetate ( 2 ) by direct nitration in one step, acted as the nitrile oxide precursor in the reaction with various alkenes. The facile conversion proceeded in the presence of equimolar amounts of PhNCO and catalytic amounts of triethylamine. The NMR spectra of the product isoxazolines 5 − 13 , showing strongly temperature‐dependent resonances of the 4′′‐CH, 4‐CH 2 and the acetyl group, are discussed, and the crystal structures of model compounds containing a methyl group instead of the isoprenoid side chain are presented. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)