Configurational effects in ¹⁷O NMR chemical shifts of hydroxyl‐substituted, bicyclo [2.2.1]heptenes and ‐heptanes, their methylated derivatives and some related compounds

Abstract

Well resolved natural abundance I7O NMR spectra of 27 mono-, di-, tri-and tetrahydroxybicyclol2.2.1 I heptenes and -heptanes (norbornenes or norbornanes), their methylated derivatives and some related compounds were measured for 0.5 M or saturated solutions in acetonitrile at 65°C. In addition, the "0 NMR chemical shifts of 14 aliphatic and alicyclic alcohols were also determined for reference purposes. The I7O NMR chemical shifts of all compounds were assigned. Both methyl-and hydroxyl-induced deshielding &effects were consistent with those reported in the literature. Similarly, observed shielding y-effects were in agreement with the earlier observations and characteristic especially for mutual y-gauche and -eclipsed orientations of substituents. In addition, clear shielding &effects (up to 10 ppm) were observed in tri-or tetrahydroxynorbornanes. These &effects can be related to the attractive van der Waals interactions observed earlier in "C NMR chemical shifts.