How can I convert the bond line view of L-idose to a Fischer projection?
1 Answer
A bond-line view gives no stereochemical information, so all 16 hexoses have the same bond line structure.
But each hexose has its own wedge-dash structure. Here are the steps to convert it to a Fischer projection.
- Draw the wedge-dash structure of the aldose.
- Draw a vertical line with C-1 (the aldehyde group) at the top and C-6 (the CH₂OH group) at the bottom.
- Draw horizontal lines to make crosses at C-2, C-3, C-4, and C-5.
- Put the OH groups and the H atoms on the correct sides of the crosses.
The wedge-dash structure of L-idose is
To convert this to a Fischer projection, we must view the molecule from the correct angle. Each chiral carbon must be closest to us, and C-1 must be at the top.
C-2: View from the upper left. This puts the OH on the right and the H on the left.
C-3: View from the lower left. This puts the OH on the left and the H on the right.
C-4: View from the upper left. This puts the OH on the right and the H on the left.
C-5: View from the lower left. This puts the OH on the left and the H on the right.
The Fischer projection of L-idose then becomes
