Chapter 20.4, Problem 20.13P

(a)

Interpretation Introduction

Interpretation:

The given L-Fucose has to be identified whether it is a $\alpha or\beta$ anomeric form.

Concept introduction:

• Haworth projection is used to represent sugars in their cyclic hemiacetal forms.
• In Haworth projection,

  $\text{α}$-indicates, the $–OH$ group of anomeric carbon $C1$ and ${\text{CH}}_{\text{2}}\text{OH}$ substituent on the $C5$ carbon is trans to each other. $\beta$-indicates, the $–OH$ group of anomeric carbon $C2$ and ${\text{CH}}_{\text{2}}\text{OH}$ substituent on the $C5$ carbon is cis to each other.

(b)

Interpretation Introduction

Interpretation:

The missing oxygen of L-Fucose as compared to galactose has to be identified.

Concept introduction:

The structure of L-Fucose is,

The structure of L-galactose is,

(c)

Interpretation Introduction

Interpretation:

The positons of $–OH$ groups on carbons of 2, 3 and 4 of L-Fucose as compared to L-galactose has to be identified.

Concept introduction:

The structure of L-Fucose is,

The structure of L-galactose is,

(d)

Interpretation Introduction

Interpretation:

The suitability of name 6-deoxy-L-galactose for L-Fucose has to be explained.

Concept introduction:

The structure of L-Fucose is,

The structure of L-galactose is,

The missing oxygen of L-Fucose as compared to galactose is on carbon atom 6.