B.R.S.M. The road to Tet. Lett. Is paved with good intentions


(+)-Loline Alkaloids

2330 - update: Just noticed the Tot. Syn. writeup. Check it out for an alternative discussion! Funny that this work's two weeks old, yet we both write about it today!

An Efficient Synthesis of (+)-Loline Alkaloids

D. Trauner et al., Nature Chemistry, 2011, 3, 543 [PDF][SI][GROUP]

DOI: 10.1038/nchem.1072

I just noticed this very efficient enantioselective synthesis of a trio of the loline pyrrolizidine alkaloids reported by Trauner and coworkers back in June. Although loline has been known for more than a century, prior to this work only one enantioselective synthesis had been reported, and at 20 steps in length - that's well over two synthetic operations per carbon atom - it's as good an example as any to illustrate the point that size isn't always what makes a target challenging. Trauner, with characteristic German efficiency, took only 9 steps to reach loline through clever use of some simple and largely well established chemistry. Reading this paper reminds me of one of the most important axioms for designing anything (syntheses, websites, software, machinery...): that a thing should only be as complicated as it needs to be - and no more.

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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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