Proton magnetic resonance studies of compounds with bridgehead nitrogen. 38—solvent effects in the 1H NMR spectra of nitrogen heterocyclic systems containing a 1,3-arrangement of heteroatoms

Solvent effects on the ¹H NMR parameters of perhydro-oxazolo3,4?a]pyridine, perhydropyrido1,2?c]?1,3]oxazine and perhydrothiazolo3,4?a]pyridine derivatives are described. Particularly marked are changes in the proton-proton geminal coupling constants of the NCH₂O and NCH₂S methylene protons with solvent and these are attributed to reaction field and solvation effects rather than to changes in the position of conformational equilibria.