The (1)H NMR spectra of a number of alcohols, diols and inositols are reported and assigned in CDCl(3), D(2)O and DMSO-d(6) (henceforth DMSO) solutions. These data were used to investigate the effects of the OH group on the (1)H chemical shifts in these molecules and also the effect of changing the solvent. Inspection of the (1)H chemical shifts of those alcohols which were soluble in both CDCl(3) and D(2)O shows that there is no difference in the chemical shifts in the two solvents, provided that the molecules exist in the same conformation in the two solvents. In contrast, DMSO gives rise to significant and specific solvation shifts. The (1)H chemical shifts of these compounds in the three solvents were analysed using the CHARGE model. This model incorporates the electric field, magnetic anisotropy and steric effects of the functional group for long-range protons together with functions for the calculation of the two- and three-bond effects. The long-range effect of the OH group was quantitatively explained without the inclusion of either the C--O bond anisotropy or the C--OH electric field. Differential beta and gamma effects for the 1,2-diol group needed to be included to obtain accurate chemical shift predictions. For DMSO solution the differential solvent shifts were calculated in CHARGE on the basis of a similar model, incorporating two-bond, three-bond and long-range effects. The analyses of the (1)H spectra of the inositols and their derivatives in D(2)O and DMSO solution also gave the ring (1)H,(1)H coupling constants and for DMSO solution the CH--OH couplings and OH chemical shifts. The (1)H,(1)H coupling constants were calculated in the CHARGE program by an extension of the cos(2)phi equation to include the orientation effects of electronegative atoms and the CH--OH couplings by a simple cos(2)phi equation. Comparison of the observed and calculated couplings confirmed the proposed conformations of myo-inositol, chiro-inositol, quebrachitol and allo-inositol. The OH chemical shifts were also calculated in the CHARGE program. Comparison of the observed and calculated OH chemical shifts and CH.OH couplings suggested the existence of intramolecular hydrogen bonding in a myo-inositol derivative.

The conformations of cyclopentanol and cis-and trans-cyclopentane-1,2-diol have been studied by ab initio and molecular mechanics (MM) calculations and by the LIS technique, using Yb(fod) 3 to obtain the induced shifts of all 1 H and 13 C nuclei in the molecule, together with complexation shifts obtained by the use of La(fod) 3 . The MM calculations gave two optimised geometries for cyclopentanol. These were envelope conformations with the hydroxyl group equatorial (1A) and axial (1B) at the flap of the envelope. In contrast Gaussian 98 at the B3LYP level with the 6-31G** basis set gave an optimised geometry (1C) which was an envelope conformation with the hydroxyl group in an axial position at the fold of the envelope. ∆E(1A Ϫ 1B) = 0.47 kcal mol Ϫ1 (MM) and 0.93 kcal mol Ϫ1 (ab initio) and ∆E (1B Ϫ 1C) = 0.15 kcal mol Ϫ1 (ab initio). The MM and ab initio calculations for cis-1,2-cyclopentanediol gave different envelope conformations (2A) and ( 2B), both with one equatorial and one axial hydroxyl group. For trans-1,2-cyclopentanediol both calculations gave the same geometries, an envelope conformation with two axial hydroxyls (3A) and a half chair conformer with diequatorial hydroxyls (3B). ∆E (3A Ϫ 3B) = 2.9 kcal mol Ϫ1 ( MM) and 0.70 kcal mol Ϫ1 (ab initio). The LIRAS4 model involving an sp 3 hybridised oxygen atom with two symmetric lone pairs was used for these compounds. The calculated LIS for cyclopentanol gave poor agreement with the observed data for 1A, moderate agreement for 1B but good agreement for 1C. A LIS analysis combining 1B and 1C suggests that the population of 1C was >80% in CHCl 3 solution. The ab initio calculations and the LIS analysis agree that the unsymmetric conformer 1C is the major form in solution. The similarity between this conformer of cyclopentanol and that of the furanose sugars suggests that the anomeric effect may be more fundamental than hitherto realised. In cis-cyclopentane-1,2-diol the observed data were in good agreement with the calculated LIS for both 2A and 2B. In trans-cyclopentane-1,2-diol the observed data were in good agreement with the calculated LIS for 3B but in poor agreement for 3A. The LIS allowed the assignment of the proton chemical shifts of the individual methylene protons in these molecules which had not been given previously.

The conformations of cis-(1) and trans-cyclopentane-1,3-diol (2) have been studied by ab initio (Gaussian 98) and molecular mechanics (PCMODEL) calculations and by NMR spectroscopy. The calculations gave two low-energy conformations for (1), 1A and 1B, both with axial hydroxyl groups. Two conformations with equatorial hydroxyl groups (1C and 1D) were found but with much higher energy (ca 4.0 kcal mol −1 ). These novel findings are considered with previous data on cyclopentanol and cis-and trans-cyclopentane-1,2-diol and it is shown that the axial hydroxyl substituent at the fold of the envelope appears to be a major factor in determining the conformational energies of these compounds.