Synthesis
Ephedrine can be synthesized from benzaldehyde in a few different ways. According to the first, benzaldehyde is condensed with nitroethane, giving 2-methyl-2-nitro-1-phenylethanol, which is reduced to 2-methyl-2-amino-1-phenylethanol. The necessary L-isomer is isolated from the mixture of isomers by crystallization. Methylation of this gives ephedrine.
The second method consists of the fermentation of glucose by yeast carboligase in the presence of benzaldehyde, which during the process turns into phenylacetylcarbinol. This is reduced by hydrogen in the presence of methylamine to give the desired ephedrine.
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