Total Synthesis Blog

You can read here today about total synthesis of (+)-Isofregenedol and, in my opinion, this is the very total synthesis which looks like a magic. In one aspect, at least.

Let’s see our current target molecule:

It looks interestingly. Only one chiral carbon atom, but five-substituted aromatic ring – in other hand. This stuff is a diterpene which was isolated from chilean flower Haplopappus parvifolius by Niemeyer in 1991. (+)-Isofregenedol exhibits important biological activites. It’s – for example – methionine aminopeptidase-2 reversible inhibitor, agonist of glucocorticoid receptor and agonist of serotonin 5-HT₇ receptor. Sounds seriously.

Before you’ll see how this molecule were prepared, I’ll show you my approach to its organic synthesis. First – retrosynthesis:

As you can see, my synthesis would be start with bromoxylene. However, I know that there could be some problems with regioselectivity during Friedel-Crafts acylation step. But see:

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This time short synthesis of racemic Cacalol:

This is a sesquiterpene isolated from the roots of Psacalium decompositum and it exhibit some interesting biological properties including antihyperglycemic, anti-inflammatory, antimicrobial and antioxidant activities. Authors of paper didn’t mention anything about biological activity of single enantiomers of Cacalol.

Retrosynthesis chart (not very good-looking…) is shown below:
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