Synthesis of Phenanthrene Alkaloids from Herbal Aporphine Alkaloids in Subcritical Water Using Synthesis of Seco-Glaucine as an Example

Transformation of the model aporphine alkaloid glaucine into the phenanthrene alkaloid secoglaucine (seco-GL) in subcritical water at 100–250°C without catalytic additives is studied. The maximum yield of seco-glaucine is achieved at 250°C. It is shown that under these conditions the load of the initial compound affects only slightly the yield of the target compound, which is on average 80%. The increase of the GL load up to 400 mg results in precipitation of the target seco-GL directly from the reaction mixture. The suggested method avoids the use of costly and toxic organic solvents.