Chapter 3 The Amaryllidaceae Alkaloids

Total synthesis of the Amaryllidaceae alkaloid clivonine

“…These alkaloids 15 can mostly be classified as belonging to one of eight skeletally distinct subclasses all derived biosynthetically from a common precursor, norbelladine. [1][2][3] Clivonine (1), along with homolycorine (2), hippeastrine (3) and lycorenine (4) are prominent members of the lycorenine subclass; these alkaloids 20 feature a tetracyclic 2-benzopyrano-[3,4-g]indole skeleton and display growth inhibition of various tumour cells, [4][5][6] DNA binding properties, 7 anti-viral activity, 8,9 antifungal activity, 10 and insect antifeedant activity 11 ( Figure 1). 12 (+)-Clivonine (1) was first isolated as white prisms in 25 0.0007% yield from an ethanolic extract of freshly collected rhizomes and leaves of Clivia miniata Regel in 1956 by Wildman, who also tentatively proposed the correct gross topology of the molecule.…”

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“…ambelline, caranine, crinamine, crinine, lycorine, narwedine, tazettine, ismine and galanthine (50 mg/Kg, in rabbits) 31,50 , while haemanthamine exhibited hypertensive properties 51 . The alkaloid narwedine was found to decrease the frequency of cardiac contractions, while galanthamine is known to cause bradycardia or atrioventricular conduction disturbance 52 . Galanthamine HBr was found to cause a fall in blood pressure in anaesthetized dogs, an effect apparently associated with a transient decrease in respiration 53 .…”

Synthesis of Some Members of the Hydroxylated Phenanthridone Subclass of the Amaryllidaceae Alkaloid Family

“…The mixture was stirred under a H 2 atmosphere at rt overnight, filtered through celite and concentrated under reduced pressure. The crude residue was subjected to flash silica gel chromatography to give 6 mg (80%) of (±)-7-deoxypancratistatin (10) as a colorless oil 13 ; 1 …”