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NMR and quantum‐chemical study of the stereochemistry of spiroepoxides obtained by oxidation of ( Z )‐3‐arylidene‐1‐thioflavan‐4‐ones
Author(s) -
Tóth Gábor,
Kovács József,
Lévai Albert,
Kleinpeter Erich,
Koch Andreas
Publication year - 2001
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/mrc.840
Subject(s) - chemistry , conformational isomerism , ab initio , quantum chemical , chemical shift , nuclear magnetic resonance spectroscopy , computational chemistry , envelope (radar) , maxima and minima , spectroscopy , cis–trans isomerism , stereochemistry , crystallography , molecule , organic chemistry , quantum mechanics , physics , telecommunications , mathematical analysis , radar , mathematics , computer science
Abstract Epoxidation of ( Z )‐3‐arylidene‐1‐thioflavan‐4‐ones ( 1 ) yielded trans,cis ( 2 ) and trans,trans ( 3 ) isomers. The structure and signal assignments were elucidated by extensive application of one‐ and two‐dimensional 1 H and 13 C NMR spectroscopy. The conformational analysis was achieved by the application of 3 J (C,H) couplings and ab initio MO calculations. Both the preferred ground‐state conformers (envelope‐A conformations) obtained as global minima of the HF ab initio structures and the 13 C chemical shifts calculated by the GIAO method from the global minima structures of the trans,cis and trans,trans isomers are in agreement with the experimentally obtained NMR results. Copyright © 2001 John Wiley & Sons, Ltd.