Configurational and conformational insights on exo‐ and en do‐1, 4:3, 6‐dianhydroglucitol mononitrate

Abstract

A PMR study of the 1,4: 3,6-dianhydroglucitol mononitrates allows the easy attribution of the 2-exo-or 5-endo nitrate configuration to each of the isomers. Coupling data obtained in chloroform and in pyridine provide insight into their conformations. The solvent shifts indicate a hydrogen bridged solute-solvent complex in the exo-compound, but a random solvation for the endo-nitrate.NMR spectral data SPECTRA of 1,4 : 3,6-dianhydroglucitol dinitrate and the two isomeric mononitrates (the 2-ex0 nitrate (I), ,L = ONO,, 5L = H and the 5-endo nitrate (l), = H, 5L = ONO,) were obtained for chloroform and pyridine solutions respectively (Spec. No. 0350-0354). The spectral information extracted is presented in Table 1. Values of coupling constants for the ABMY spin systems were obtained graphically by the subspectral pr0cedure.l The most striking features are (a) the isochronism (shift degeneration) of the H-2 atoms for the chloroform solutions, but disappearing in pyridine, (b) the absence of any appreciable coupling between H-2 and H-3, as was also observed in the ditosylate and dimesylate,, (c) the typical solvent induced shift values for the exo-and endo-isomer respectively, and (d) the difference in ,J-values for CH,-2 (pyridine) and CH,-6 (in chloroform and pyridine).The first point is connected with the observation that in changing a vicinal hydroxyl group into a nitrate group a downfield shift of 0.1 to 0.25 ppm occurs. Observation (b) indicates, as can easily be seen in DKEIDING models of the cis-joined" bicyclic system, that only H-2 can be involved in a vicinal coupling equalling zero. This allows a direct structure assignation for the respective isomeric mononitrates.

Improved automated simultaneous determination of isosorbide dinitrate and its metabolites in plasma by capillary column gas chromatography

“…lsomannide mononitrate (IMMN) and isoidide mononitrate (IIMN) were synthesized according to a method described elsewhere [15].…”