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13 C NMR studies of 2,3‐dihydrofurans. Restricted rotation of bulky aryl rings in cis ‐2‐aryl‐3‐methyl‐2,3‐dihydrofurans
Author(s) -
Convert Odile,
Touboul Estera,
Dana Gilbert
Publication year - 1984
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270221008
Subject(s) - aryl , chemistry , rotation (mathematics) , nmr spectra database , proton nmr , stereochemistry , carbon 13 nmr , spectral line , methyl group , medicinal chemistry , group (periodic table) , physics , organic chemistry , mathematics , alkyl , geometry , astronomy
13 C NMR spectra of some 2,3‐dihydrofurans were measured. Restricted rotation of the bulky aromatic groups of cis ‐2‐aryl‐3‐methyl‐2,3‐dihydrofurans is observed when these groups have substituents in both ortho positions. Barriers to rotation were deduced from the variations in line widths of the 13 C NMR signals. Exchange rates are highly affected by the buttressing effect of meta ‐methyl groups.