Converting Fischer Converting Fischer structures to Haworth and structures to Haworth and chair formschair forms

Start with the Fischer Start with the Fischer (Rosanoff) structure(Rosanoff) structure

D-glucose

Form the pyranose ringForm the pyranose ring

D: CHD: CH22OH at C5 goes upOH at C5 goes up

L: CHL: CH22OH at C5 goes downOH at C5 goes down

O5

This is a D-sugarThis is a D-sugar

O

H

CH2OH

Determine alpha or Determine alpha or betabeta

If OH at C1 is on the same side If OH at C1 is on the same side of the ring as the CHof the ring as the CH22OH group, OH group, the sugar is betathe sugar is beta

If the OH at C1 is on the If the OH at C1 is on the opposite side of the ring as the opposite side of the ring as the CHCH22OH group, the sugar is alphaOH group, the sugar is alpha

Let’s make our example betaLet’s make our example beta

The beta anomerThe beta anomer

O

H

HOH

CH2OH Same side

What remains to be What remains to be done?done?

We need to know the We need to know the configuration of the OH groups configuration of the OH groups at carbons 2, 3, and 4at carbons 2, 3, and 4

How do we do this?How do we do this? Go back to the Fischer Go back to the Fischer

(Rosanoff) projection(Rosanoff) projection Then lay it over on it’s side to Then lay it over on it’s side to

the rightthe right

Fischer structureFischer structure

D-glucose

Place remaining OH Place remaining OH groupsgroups

Put the remaining OH groups Put the remaining OH groups on the Haworth ring at C2, C3, on the Haworth ring at C2, C3, and C4 in the same orientation and C4 in the same orientation (up or down) as they are in the (up or down) as they are in the leaned over Fischer/Rosanoff leaned over Fischer/Rosanoff structurestructure

Beta-D-glucopyranoseBeta-D-glucopyranose

O

HH

HH

OHOH

H OH

OH

CH2OH

Haworth to chair formHaworth to chair form

O

HH

HH

OHOH

H OH

OH

CH2OH

O

HOH

HH

H

H

OHOH

OHHOH2Ce

ae

a

a

e

e

a

a

e

beta-D-glucopyranose

(Haworth form)

beta-D-glucopyranose

4C1 chair form