Step 1: Understanding the Fischer Projection

The Fischer projection of an aldose monosaccharide is drawn by placing the aldehyde group (CHO) at the top and the CH₂OH group at the bottom.

In D-glyceraldehyde, the hydroxyl group (OH) is on the right side of the chiral carbon in the Fischer projection.

Step 2: Converting to a 3D Structure (Wedge and Dash Bonds)

• Horizontal bonds (OH and H): Represented as wedge bonds (coming out of the plane).
• Vertical bonds (CHO and CH₂OH): Represented as dash bonds (going behind the plane).

This method ensures that the stereochemistry at the chiral center remains unchanged.

Explanation Summary

Using the above method, we can correctly convert the Fischer Projection using wedge and dash bonds without changing the configuration at the chiral carbon.

Correct 3D Structure of D-Glyceraldehyde

– CHO and CH₂OH groups are shown as dash bonds.
– OH and H are shown as wedge bonds.
– This reflects the D-configuration of glyceraldehyde in three dimensions.

Conclusion

This method provides a reliable way to convert a Fischer projection to a wedge-and-dash 3D structure, preserving stereochemistry at the chiral center. The final drawing accurately represents D-glyceraldehyde.