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Configurational 1 H NMR study of optically active 7‐(1‐phenylethyl)‐2‐oxa‐7‐azabicyclo[3.2.0]heptan‐6‐one derivatives using Pirkle’s alcohols and a chiral shift reagent
Author(s) -
GarcíaMartínez Cirilo,
Taguchi Yoichi,
Oishi Akihiro,
Hayamizu Kikuko
Publication year - 1998
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/(sici)1097-458x(199806)36:6<429::aid-omr306>3.0.co;2-t
Subject(s) - chemistry , enantiomer , isocyanate , nuclear magnetic resonance spectroscopy , absolute configuration , reagent , chiral derivatizing agent , stereochemistry , asymmetric carbon , organic chemistry , optically active , chiral column chromatography , polyurethane
Four novel stereoisomers of 7‐(1‐phenylethyl)‐2‐oxa‐7‐azabicyclo[3.2.0]heptan‐6‐one were prepared under high pressure from [2+2] cycloaddition of the pure enantiomers of 1‐phenylethyl isocyanate and 2,3‐dihydrofuran. Their conformational preferences in solution and the absolute configurations of the bridgehead carbon atoms were unambiguously determined by 1 H NMR spectroscopy using tris[3‐(2,2,2‐trifluoro‐1‐hydroxyethylidene)‐ d ‐camphorato]europium(III) and ( R )‐ or ( S )‐1‐(9‐anthryl)‐2,2,2‐trifluoroethanol (Pirkle’s alcohols). MM2 single‐point energy calculations were consistent with the experimentally determined stereochemistry. ©1998 John Wiley & Sons, Ltd.