SYNTHESIS AND NMR SPECTRA OF TETRAHYDROFURAN-2- 13 C

Abstract

An original method was developed for the synthesis of THF labeled selectively with the 13 C isotope at the α-carbon atom. The effective reduction of symmetry brought about by the insertion of the isotopic label removes the excess degeneracy of the spin systems describing the multiplet structure of the 1 H and 13 C NMR spectra, making it possible to undertake a detailed analysis. Exact values for the 1 H– 1 H spin-spin coupling constants through four bonds and also the 13 C– 1 H and 13 C– 13 C spin-spin coupling constants involving the α-carbon atom were determined for the first time. The isotopic chemical shifts of the protons and 13 C nuclei caused by replacement of the 12 C nucleus by 13 C were determined. These data can be used to construct a quantitative model of the conformational behavior of THF as a molecular system in which pseudorotation in terms of vibrations with large amplitude is realized. Authors: A. V. Chertkov, A. K. Shestakova, and V. A. Chertkov. English Translation in Chemistry of Heterocyclic Compounds , 2012, 48 (3), pp 412-421 http://link.springer.com/article/10.1007/s10593-012-1008-0