Premium
Stereochemistry of alkyl 3‐substituted 4‐halotetrahydro‐2‐oxo‐3‐furancarboxylates: 2 — 1 H and 13 C NMR spectra
Author(s) -
GryffKeller A.,
Kołodziejek W.,
Prejzner J.
Publication year - 1983
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/omr.1270210302
Subject(s) - vicinal , chemistry , halogen , alkyl , ring (chemistry) , stereochemistry , nmr spectra database , cis–trans isomerism , proton nmr , solvent , spectral line , organic chemistry , physics , astronomy
The 1 H NMR parameters of methyl 3‐substituted cis ‐4‐halotetrahydro‐2‐oxo‐3‐furancarboxylates are reported, with assignments of the ring protons based on solvent‐induced changes in the vicinal trans coupling constants, 3 J (H‐4, H‐5). Preferred conformations, ce with a pseudo‐equatorial halogen for the cis isomers and ta with a pseudo‐axial halogen for the trans isomers, have been suggested on comparison of the magnitudes of J(trans) and J(gem) in both series. The 3 J ( 13 CH 3 , H‐4) values measured for methyl cis ‐4‐bromotetrahydro‐3‐methyl‐3‐furancarboxylate, methyl trans ‐4‐bromotetrahydro‐3‐methyl‐3‐furancarboxylate and trans ‐3,4‐dibromodihydro‐3‐methyl‐2(3 H )‐furanone have confirmed the stereochemical assignments.