First Synthesis of N-(3-Carboxylpropyl)-5-amino-2-hydroxy-3- tridecyl-1,4-benzoquinone, an Unusual Quinone Isolated from Embelia ribes

The first synthesis of the unusual nitrogen-containing 3-alkyl-1,4-benzoquinone, N-(3-carboxylpropyl)-5-amino-2-hydroxy-3-tridecyl-1,4-benzoquinone, isolated from Embelia ribes, is reported. The key steps are a microwave-assisted combined Mitsunobu reaction-Claisen rearrangement to introduce the alkyl side chain into 2,5-dimethoxyphenol, followed by alkene reduction, oxidation to the quinone, and sequential displacement of the methoxy groups with hydroxide and GABA tert-butyl ester. Two other naturally occurring benzoquinones, O-methylrapanone and rapanone, were also prepared en route.