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Reverse anomeric effect of the carbamoyl group of 2,6‐disubstituted 6‐carbamoyl‐5,6‐dihydro‐2 H ‐pyrans
Author(s) -
Chmielewski Marek,
Jurczak Janusz,
Priebe Waldemar,
Horton Derek
Publication year - 1987
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.1260250215
Subject(s) - chemistry , stereochemistry , anomeric effect , anomer , cyclohexane conformation , coupling constant , ring (chemistry) , organic chemistry , hydrogen bond , molecule , physics , particle physics
The 1 H NMR spectra of 2,6‐disubstituted 6‐carbamoyl‐5,6‐dihydro‐2 H ‐pyrans and their 6‐methoxycarbonyl analogs have been recorded. With the use of coupling constants between ring protons, the conformational preference of the carbamoyl group has been evaluated. The 1 H 6 ⇌ 6 H 1 conformational equilibria in the above compounds are discussed. It is found that the conformational tendency of the carbamoyl group to the equatorial disposition helps to determine the conformational equilibrium in the seven examples studied.