Total Synthesis Blog

Do you know snowdrops? It’s well-known that bulbs of these flowers (latin name is Galanthus nivalis) contain many alkaloids and galantamine (or galanthamine) is one of them:

This is an important natural product because of its biological properties and phamacological applications – it’s used in treatment of mild Alzheimer’s disease. So there are many approaches to total synthesis of galantamine and here I’ll try to show most recent of them (I think so).

Authors of the paper on which I base developed new interesting reaction: DMCRC – what means Double Michael-Claisen Reaction Cascade. The reaction allows to synthesise quickly highly substituted cyclohexenones which can be used in total syntheses of many ’sterically congested’ natural products and galantamine is only one of several examples mentioned in paper (the others are aspidospermidone, lycoramine and  mesembrine).

Let’s look at retrosynthetic analysis:

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Back again! Today great and classic target: cholesterol (click on image to enlarge it).

When I was preparing to my summer Natural Product Exam and when I was admiring how Nature ‘do’ such big molecules by biosynthetic routes I just wanted to know how R. B. Woodward could synthesize such complex molecule like cholesterol. Well, it was more complicated than I expected. By the way – articles from 1950s are so difficult to read… there are no chemical equations and no schemes in some of them.

But let’s see how Woodward did his synthesis, but first let’s remind designation of steroids fused-ring system:

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