A New Synthetic Pathway for Saxitoxin

Saxitoxin, mostly noted as a toxin in oceanic red tide poisonings, has become a significant target of interest for synthetic organic chemists, due to the challenges associated with its efficient synthesis and its use in probing sodium ion channels. The main goal of this study was to determine an efficient way in synthesizing saxitoxin by improving the product yield and/or reducing the number of steps necessary to produce it. The beginning steps of a possible pathway involve the esterification and protection of β-alanine. When this amino acid is heated with acetyl chloride in methanol, a methyl 3-aminopropanoate is formed. This amino ester can then be protected as a carbamate using Di-tert-butyl dicarbonate  and a mixture of dichloromethane and sodium carbonate, to give methyl 3-[(tertbutoxycarbonyl)amino]propanoate. We hope to determine a synthetic pathway that is short in the number of steps with high product yields overall. A successful synthesis of saxitoxin should not only provide improved access to this valuable molecule and its derivatives, but also open the door to new strategies for polar, nitrogen-rich functional group chemistry.