CONFORMATION OF NON-AROMATIC RING COMPOUNDS .52. NMR SPECTRA AND DIPOLE MOMENTS OF 2-ALKOXYTETRAHYDROPYRANS

The conformational equilibrium of six 2-alkoxytetrahydropyrans has been studied by means of vicinal coupling constants and dipole moments. The alkoxy group prefers the axial orientation to the extent of 0-1 kcal/mole, which is in agreement with earlier results. From the linear relationship between μ2 and J it follows that out of the six possible conformers of the COCOC moiety, two (or three) predominate in the mixture, one axial and one (or two) equatorial forms. A comparison is made with the conformation of the anomeric alkoxy group with respect to the ring as found in pyranosides by X-ray analyses. © 1969.