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The NMR spectra and conformations of dihydropyran derivatives—I: The conformations of 2‐alkoxy‐5,6‐dihydro‐α‐pyran‐6‐carboxylic esters
Author(s) -
Achmatowicz O.,
Jurczak J.,
Konowal A.,
Zamojski A.
Publication year - 1970
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.1270020107
Subject(s) - alkoxy group , dihydropyran , chemistry , pyran , stereochemistry , nmr spectra database , carboxylic acid , medicinal chemistry , spectral line , organic chemistry , catalysis , alkyl , physics , astronomy
On the basis of NMR spectra of trans ‐ and cis ‐2‐alkoxy‐5,6‐α‐pyran‐6‐carboxylic esters it was found that, at room temperature, the trans ‐compounds exist exclusively in the conformation with equatorial carbalkoxy and pseudoaxial alkoxy groups. The cis ‐isomers appear to be in conformational equilibrium between a form with equatorial carbalkoxy and pseudoequatorial alkoxy groups and that with axial and pseudoaxial substituents. In the latter case, the axial carbalkoxy group is bent out off its normal position by about 15°.