What question did this study set out to answer?

The research aims to explore the conformational characteristics of iminocyclitols using a 3-spherical approach to analyze NMR data and stereochemical parameters.

February 12, 2026Open Access

3-Spherical Conformational Insights into Iminocyclitols with 1-α-D-Ribose and 1-β-L-Ribose Stereochemistry Under Homotopic Behaviour of Nuclear Magnetic Resonance Data

Key Points

The research aims to explore the conformational characteristics of iminocyclitols using a 3-spherical approach to analyze NMR data and stereochemical parameters.
Utilized 3-sphere hypersphere approach for stereochemical parameter calculations.
Analyzed dihedral and tetrahedral angles using NMR data and vicinal coupling constants.
Calculated phase angles of pseudorotation and examined conformers through molecular modeling techniques.
Identified two conformers for 1-α-methyl-1,4-imino-1,4-dideoxy-D-ribitol with varying dihedral and tetrahedral angles.
Mapped phase angle of pseudorotation showing distinct regional placements for D and L ribitols.
Demonstrated homotopic switches in NMR data consistent with transformations in angles and energy relations.

Abstract

3-Sphere, a hypersphere in 4 dimensions approach, applied for calculating stereochemical parameters of iminocyclitol 1 – 5 with Hopf fibration and Lie algebra is described. Three angles have been considered, ii.e./i dihedral θsubHnHn+1/sub deg – tetrahedral φsubCn/sub deg – phase angle of the pseudorotation P deg calculated from NMR data, vicinal coupling constant sup3/supiJ/isubHH/sub Hz and carbon chemical shift δsubC/sub ppm. This approach gave for 1-α-methyl-1,4-imino-1,4-dideoxy-D-ribitol 2 two conformers Esub3/sub and sup3/supTsub2/sub having different dihedral θsubHnHn+1/sub deg and tetrahedral φsubCn/sub deg angles with same vicinal angles ϕ deg. Notably, phase angle of pseudorotation P deg placed the conformations on the south side for D-ribitols 1 - 3 and on the north side for L-ribitol 4, excepting trifluoroacetate salt of L-ribitol 5. The wave character of NMR data introduced few homotopic switches, the transformation from torus to inverse of torus, the relationship between angles of set A and set B, the transformation from Planck constants h to h-bar, along with the transformation from Joule to Calorie (J 4.1868 ⇆ Jsup-1/sup 0.238). Two methods for calculation of tetrahedral angles φsubCn/sub deg, energy-graph and Euler conic with two ways for representing the angles, polyhedron and unit models are analyzed. The conformational parameters, phase angle of the pseudorotation P deg established with VISION molecular model and exocyclic 3-Sphere dihedral angles θsubHnHn+1/sub deg relative to endocyclic torsional angles θsubn,n/subsub+1/sub deg from Altona-Sundaralingan model have been evaluated. In addition, the corresponding angle of deviation from planarity θsubm/sub deg has been determined.

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