B.R.S.M. To strive, to seek, to find and not to give a yield


Top Five Syntheses of May/June 2011

Here's an idea for a feature I've not seen anywhere else that I thought I'd try. It wasn't easy to choose, and my tastes in chemistry may be different to yours. These are not in any kind of order, because that would be silly. Please point out any nice work I've missed in the comments!

KCN's first dithiodiketopiperazine

Total Synthesis of Epicoccin G [PDF][SI][GROUP]

DOI: 10.1021/ja2032635

K. C. Nicolaou et al.J. Am. Chem. Soc., 2011, 133, 8150–8153

I was contemplating doing a full write up of this when I started blogging at the start of this month, but I'm not sure I'll get round to it now, unless it's a quiet few weeks or people really want to see one (let me know!). KC chooses a fantastically non-obvious disconnection for this molecule; the two g-hydroxycyclohexanones are actually derived from two molecules of tyrosine using a neat oxidative dearomatisation procedure developed by Wipf, followed by dimerisation. These spend most of the route masked as the 1,3-cyclohexadienes only to be revealed in the penultimate step by a [4 + 2] with singlet oxygen, followed by a Kornblum - DeLaMare rearrangement. How often do you see those?

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The Catalytic Enantioselective Total Synthesis of (+)-Liphagal

Stoltz et al., Angew. Chem. Int. Ed., 2011, Early View; [PDF] [SI] [GROUP HOMEPAGE]

DOI: 10.1002/anie.20110184

This tetracyclic meroterpene has had quite a bit of attention from the synthetic community since its isolation back in 2006 from a Caribbean sponge. Along with other well known natural products such as resveratrol, staurosporine, and wortmannin it's an inhibitor of phosphatidylinositol 3-kinase (PI3K), an enzyme involved in numerous diseases. The fact that those all have wikipedia pages is quite telling. It's also got some cytotoxicity towards various cancer cell lines, but I suspect the reason people keep making it is the unique and interesting 6-7-5-6 ring system.

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