Question

The sugar D-gulose is a sweet-tasting syrup. (13.3, 13.4)

a. Draw the Fischer projection for L-gulose.

b. Draw the Haworth structures for $\alpha$- and $\beta$-D-gulose.

Short answer

Part a) An Anomer of a saccharide only differs in its structure at the anomeric carbon.

Part b) Anomeric carbon is the functional group of the carbohydrate, which is usually the carboxyl group attached to it.

Part c) Epimeres, differ at only one chiral center, not the anomeric carbon.

Step-by-step solution

Introduction (Part a)

Aldehydo-L-glucose is the L-enantiomer of aldehydo-glucose. It is a L-glucose and an aldehydo-glucose. It is an enantiomer of analdehydo-D-glucose.

Draw the Fischer projection for L-gulose. (Part a)

$-\mathrm{OH}$on farthest chiral $\mathrm{C}$is on left so it is $L-$Glucose

b) Draw the Haworth structures for α - and β-D-gulose.

The Haworth structure.