# ᴅ-amphetamine, ʟ-amphetamine

The following structural formula (source: Wikimedia) is labelled ᴅ-amphetamine:

A Fischer projection of this molecule would contain, I think, the following line:

$$\ce{H2N-C-H},$$

and I would have labelled the molecule therefore as ʟ-amphetamine.

Why am I wrong? Why is it called ᴅ-amphetamine?

The blue box in right-hand corner explains how L- and D-$$\alpha$$-amino acids get their names using Fischer projection (this is similar to D- and L-monosaccharides, replacing $$\ce{OH}$$ group by $$\ce{NH2}$$ group). If you reduced the carboxylate group of amino acid to a methyl group, the optical rotation of $$\alpha$$-carbon change from $$(S)$$ to $$(R)$$ because second highest priority of $$\ce{COOH}$$ group to third highest ($$\ce{CH3}$$ group) based on the size of the $$\ce{R}$$ group (see general formula of amino acid in top right corner). For example, when $$\ce{R=CH2Ph}$$ group, the amino acid is phenylalanine, which has $$(S)$$-rotation, but reduction of caboxylate group to methyl make the rotation $$(R)$$. However, the product $$(R)$$-amphetamine still carries the original L-nomenclature (see examples in bottom red box).