Oxygen → Vincamine

Beteiligte Stoffe

Reaktionsschritte

1 gr of tabersonine was dissolved in 150 ml of methanol containing 0.0066% (weight/volume) of Rose Bengal as a photosensitizer. 2 ml of NaOH 2 N and 1.5 ml of triethyl phosphite were added and irradiation was provided with a tungsten lamp of 300 W for about 50 minutes, maintaining a constant flow of oxygen equal to 5-10 l/hour and a temperature of 20° C. in the solution. After the reaction was complete, the solution was concentrated to a residue under reduced pressure, taken up with chloroform and filtered on neutral alumina. The solvent was dry evaporated, the residue was taken up with 20 ml of glacial AcOH and 2 gr of AcONa.3H2O, 150 ml of methanol was added and dilution was made to 300 ml with water, then refluxing was conducted for 15 minutes. The solution was cooled, alkalized at pH 8.5-9 with concentrated ammonium hydroxide and extracted with chloroform. The organic extracts were combined, washed with water, dried on sodium sulfate, filtered and concentrated into a residue. The residue was recrystallized from methanol. 600 mgr of Δ14 -vincamine (yield of 57%) and 200 mgr of Δ14 -16-epivincamine (yield of 19%) were obtained. The physico-chemical data of the obtained products were identical to those of corresponding reference compounds.

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