Manufacturing by-products from, and stereochemical outcomes of the biotransformation of benzaldehyde used in the synthesis of methamphetamine

Clandestine synthesis of methamphetamine in Australia has predominantly started from pseudoephedrine extracted from over the counter cold and flu medications. However, recently introduced restrictions on the sale of these products have made pseudoephedrine much more difficult to obtain. As a result clandestine chemists have had to resort to other means of obtaining the necessary chemical precursors. A recent drug raid (Adelaide, January 2008) resulted in the seizure of an unusual reaction mixture that indicated a novel approach involving the fermentation of glucose by yeast in the presence of benzaldehyde to give 1-hydroxy-1-phenylpropanone, also known as l-phenylacetylcarbinol (l-PAC), a known precursor to ephedrine and pseudoephedrine and hence methamphetamine. A study was undertaken into this process with the aim of determining the characteristic reaction by-products associated with methamphetamine made in this way. The study also looked at the stereochemical selectivity of the fermentation reaction and the stereochemistry of the subsequent reaction products, ephedrine and pseudoephedrine, and the final methamphetamine.