Total Synthesis Blog

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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Today, some nice total synthesis – Barrenazines A and B. Structure of these C₂-symmetrical molecules is shown below:

These Barrenazines were isolated in 2003 by Kashman from some (according to authors of article) unidentified tunicates from Barren Islands (Madagascar). They exhibit mild cytotoxic activity against certain tumor cells. The retrosynthetic analysis is shown below:

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