Chapter 3, Problem 50DSP

Interpretation Introduction

Interpretation:

The relationship of the $\text{OH}$ groups at C2 and C3 in the $\text{β-pyranose}$ form of D-ribose is to be identified.

Concept introduction:

The basic chair conformation of cyclohexane is shown below:

Two substituents are cis to each other if they are on the same side of the ring.

Two substituents are trans to each other if they are on the opposite side of the ring.

When the torsion angle between two substituents is approximately $\text{60°}$, their relationship is gauche.

When the torsion angle between two substituents is approximately $\text{180°}$, their relationship is anti.

When the torsion angle between two substituents is approximately $\text{0°}$, their relationship is eclipsed.