Question

What are the steps to convert bond line views to Fischer projections?

Answer 1

Here are the steps to convert a bond-line view to a Fischer projection.

Explanation:

The bond-line structure of D-altrose is

This structure gives no stereochemical information.

But here's how to convert a wedge-dash formula to a Fischer projection.

The wedge-dash structure of D-altrose is

(from www.chemeddl.org)

Now we can convert the wedge-dash to a Fischer projection.

(a) Arrange the molecule so that the chiral carbons and the longest continuous chain are in a vertical arrangement, with the aldehyde group at the top and the hydroxymethyl group at the bottom. Put crosses at C-2, C-3, C-4, and C-5.

(b) Put the OH group at C-2 on the correct side of the cross.

View the molecule from an angle that puts C-2 closest to our eye and C-1 at the top (the upper left). The OH group is on the left.

(c) Put the OH group at C-3 on the correct side of the cross.

View the molecule from the lower left. The OH group is on the right.

(d) Repeat at C-4, viewing from the upper left.

The OH group is on the right.

(e) Repeat at C-5, viewing from the lower left.

The OH group is on the right.

And we have the Fischer projection of D-altrose.