Chapter 18, Problem 18.78P

Interpretation Introduction

Interpretation:

The mechanism showing conversion of $\text{α-D-allopyranose}$ to $\text{α-D-allofuranose}$ under acidic conditions is to be drawn.

Concept introduction:

The electron rich O atom acts as nucleophile, and the C atom in C-O acts as electrophile in $\text{α-D-allopyranose}$.

The attack of nucleophile from top pushes the OH group on the opposite side, resulting in the formation of $\text{α-anomer}$.